MCP1603LT-330I/MC_技术文档

MCP1603

2.0 MHz, 500 mA Synchronous Buck Regulator

Features

General Description

• Over 90% Typical Efficiency

• Output Current Up To 500 mA

• Low Quiescent Current = 45 µA, typical

• Low Shutdown Current = 0.1 µA, typical

• Adjustable Output Voltage:

- 0.8V to 4.5V

The MCP1603 is a high efficient, fully integrated

500 mA synchronous buck regulator whose 2.7V to

5.5V input voltage range makes it ideally suited for

applications powered from 1-cell Li-Ion or 2-cell/3-cell

NiMH/NiCd batteries.

At heavy loads, the MCP1603 operates in the 2.0 MHz

fixed frequency PWM mode which provides a low

noise, low output ripple, small-size solution. When the

load is reduced to light levels, the MCP1603

automatically changes operation to a PFM mode to

minimize quiescent current draw from the battery. No

intervention is necessary for a smooth transition from

one mode to another. These two modes of operation

allow the MCP1603 to achieve the highest efficiency

over the entire operating current range.

• Fixed Output Voltage:

- 1.2V, 1.5V, 1.8V, 2.5V, and 3.3V

• 2.0 MHz Fixed-Frequency PWM (Heavy Load)

• Automatic PWM to PFM Mode Transition

• 100% Duty Cycle Operation

• Internally Compensated

• Undervoltage Lockout (UVLO)

• Overtemperature Protection

• Space Saving Packages:

The MCP1603 is available with either an adjustable or

fixed output voltage. The available fixed output voltage

options are 1.2V, 1.5V, 1.8V, 2.5V, and 3.3V. When a

fixed option is used, only three additional small external

components are needed to form a complete solution.

Couple this with the low profile, small-foot print

packages and the entire system solution is achieved

with minimal size.

- 5-Lead TSOT

- 8-Lead 2X3 DFN

Applications

• Cellular Telephones

• Portable Computers

• Organizers / PDAs

Additional protection features include: UVLO,

overtemperature, and overcurrent protection.

• USB Powered Devices

• Digital Cameras

• Portable Equipment

• +5V or +3.3V Distributed Systems

Package Types

5-Lead TSOT

8-Lead 2x3 DFN

L_X

1

2

3

4

8

7

6

5

GND

V_IN

V_FB/V_OUT

V_IN

L_X

SHDN

GND

L_X

1

2

3

5

4

1

2

3

5

4

NC

SHDN

GND

NC

V_IN

SHDN

V_FB/V_OUT

MCP1603

MCP1603L

DS22042A-page 1

MCP1603

Typical Application Circuit

L

V

1

OUT

IN

4.7 µH

1.8V @ 500 mA

2.7V To 4.5V

V

L

X

IN

C

4.7 µF

C

4.7 µF

IN

OUT

V

SHDN

FB

GND

100

V_OUT= 1.8V

95

90

85

80

75

70

65

60

55

50

V_IN= 2.7V

V_IN= 3.6V

V_IN= 4.5V

0.1

1

10

Output Current (mA)

100

1000

DS22042A-page 2

MCP1603

Functional Block Diagram

V_IN

V_REF

Band

Gap

Soft Start

UVLO

Thermal

Shutdown

SHDN

UVLO

ILIM_PWM

ILIM_PFM

TSD

I_PKLimit

IPEAK_PWM

IPEAK_PFM

Slope

Comp

OSC

-ILPK

NOFF

S

R

Q

POFF

L_X

Switch Drive

Logic and timing

Q

PWM/PFM

PFM Error Amp

PWM/PFM

Logic

GND

IPEAK_PFM

IPEAK_PWM

V_REF

PWM Error Amp

EA

-ILPK

-I_PKLimit

V_REF

OV Threshold

UV Threshold

UVLO

TSD

Disable

Switcher

V_FB/ V_OUT

DS22042A-page 3

MCP1603

† Notice: Stresses above those listed under "Maximum

Ratings" may cause permanent damage to the device. This is

a stress rating only and functional operation of the device at

those or any other conditions above those indicated in the

operational sections of this specification is not intended.

Exposure to maximum rating conditions for extended periods

may affect device reliability.

1.0

ELECTRICAL

CHARACTERISTICS

Absolute Maximum Ratings †

V_IN- GND.......................................................................+6.0V

All Other I/O ...............................(GND - 0.3V) to (V_IN+ 0.3V)

L_Xto GND .............................................. -0.3V to (V_IN+ 0.3V)

Output Short Circuit Current..................................Continuous

Power Dissipation (Note 5)..........................Internally Limited

Storage Temperature.....................................-65°C to +150°C

Ambient Temp. with Power Applied.................-40°C to +85°C

Operating Junction Temperature...................-40°C to +125°C

ESD Protection On All Pins:

HBM..............................................................................4 kV

MM...............................................................................300V

DC CHARACTERISTICS

Electrical Characteristics: Unless otherwise indicated, V_IN= SHDN = 3.6V, C_OUT= C_IN= 4.7 µF, L = 4.7 µH, V_OUT(ADJ) = 1.8V,

_OUT= 100 mA, T_A= +25°C. Boldface specifications apply over the T_Arange of -40°C to +85°C.

I

Parameters

Sym

Min

Typ

Max

Units

Conditions

Input Characteristics

Input Voltage

V_IN

I_OUT

I_{IN_SHDN}

I_Q

2.7

500

—

5.5

—

1

V

Note 1

Maximum Output Current

Shutdown Current

Quiescent Current

mA Note 1

0.1

45

µA SHDN = GND

—

60

µA SHDN = V_IN, I_OUT= 0 mA

Shutdown/UVLO/Thermal Shutdown Characteristics

SHDN, Logic Input Voltage Low

SHDN, Logic Input Voltage High

SHDN, Input Leakage Current

Undervoltage Lockout

V_IL

V_IH

—

45

—

15

—

%V_INV_IN= 2.7V to 5.5V

µA V_IN= 2.7V to 5.5V

I_{L_SHDN}

UVLO

-1.0

2.12

—

±0.1

2.28

140

150

10

1.0

2.43

—

V

V_INFalling

Undervoltage Lockout Hysteresis UVLO_HYS

mV

°C

Thermal Shutdown

T_SHD

—

Note 4, Note 5

Thermal Shutdown Hysteresis

T_SHD-HYS

—

Note 1: The minimum V_INhas to meet two conditions: V_IN≥ 2.7V and V_IN≥ V_OUT+ 0.5V.

2: Reference Feedback Voltage Tolerance applies to adjustable output voltage setting.

3: V_Ris the output voltage setting.

4: The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable

temperature and the thermal resistance from junction to air (i.e. T_A, T_J, θ_JA). Exceeding the maximum

allowable power dissipation causes the device to initiate thermal shutdown.

5: The internal MOSFET switches have an integral diode from the L_Xpin to the V_INpin, and from the L_Xpin

to the GND pin. In cases where these diodes are forward-biased, the package power dissipation limits

must be adhered to. Thermal protection is not able to limit the junction temperature for these cases.

6: The current limit threshold is a cycle-by-cycle peak current limit.

DS22042A-page 4

MCP1603

DC CHARACTERISTICS (CONTINUED)

Electrical Characteristics: Unless otherwise indicated, V_IN= SHDN = 3.6V, C_OUT= C_IN= 4.7 µF, L = 4.7 µH, V_OUT(ADJ) = 1.8V,

_OUT= 100 mA, T_A= +25°C. Boldface specifications apply over the T_Arange of -40°C to +85°C.

I

Parameters

Sym

Min

Typ

Max

Units

Conditions

Output Characteristics

Adjustable Output Voltage Range

Reference Feedback Voltage

V_OUT

V_FB

0.8

—

0.8

—

4.5

—

V

Note 2

-3.0

-2.5

—

+3.0

+2.5

—

%

nA

%

T_A= -40°C to +25°C

T_A= +25°C to +85°C

Reference Feedback Voltage

Tolerance

—

Feedback Input Bias Current

Output Voltage Tolerance Fixed

I_VFB

V_OUT

V_LINE-

0.1

V_R

0.3

-3.0%

-2.5

—

+3.0%

+2.5

—

T_A= -40°C to +25°C, Note 3

T_A= +25°C to +85°C, Note 3

Line Regulation

Load Regulation

%/V V_IN= V_R+ 1V to 5.5V,

I_OUT= 100 mA

REG

V_LOAD-

—

0.35

—

%

V_IN= V_R+1.5V,

I_LOAD= 100 mA to 500 mA

REG

Internal Oscillator Frequency

Start Up Time

F_OSC

1.5

—

2.0

0.6

2.8

—

MHz

T_SS

R_DSon-P

R_DSon-N

I_LX

ms T_R= 10% to 90%

mΩ I_P= 100 mA

mΩ I_N= 100 mA

R_DSonP-Channel

—

500

±0.1

—

R_DSonN-Channel

—

L_XPin Leakage Current

-1.0

1.0

µA SHDN = 0V, V_IN= 5.5V,

L_X= 0V, L_X= 5.5V

Positive Current Limit Threshold +I_LX(MAX)

—

860

—

mA Note 6

Note 1: The minimum V_INhas to meet two conditions: V_IN≥ 2.7V and V_IN≥ V_OUT+ 0.5V.

2: Reference Feedback Voltage Tolerance applies to adjustable output voltage setting.

3: V_Ris the output voltage setting.

4: The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable

temperature and the thermal resistance from junction to air (i.e. T_A, T_J, θ_JA). Exceeding the maximum

allowable power dissipation causes the device to initiate thermal shutdown.

5: The internal MOSFET switches have an integral diode from the L_Xpin to the V_INpin, and from the L_Xpin

to the GND pin. In cases where these diodes are forward-biased, the package power dissipation limits

must be adhered to. Thermal protection is not able to limit the junction temperature for these cases.

6: The current limit threshold is a cycle-by-cycle peak current limit.

DS22042A-page 5

MCP1603

TEMPERATURE SPECIFICATIONS

Electrical Specifications: Unless otherwise indicated, all limits are specified for: V_IN+ 2.7V to 5.5V

Parameters

Sym

Min

Typ

Max

Units

Conditions

Temperature Ranges

Operating Junction Temperature

Range

T_J

-40

—

+125

°C

Steady State

Storage Temperature Range

Maximum Junction Temperature

Package Thermal Resistances

Thermal Resistance, 5L-TSOT

T_A

T_J

-65

—

+150

°C

Transient

θ_JA

—

256

—

°C/W Typical 4-layer Board with

Internal Ground Plane

Thermal Resistance, 8L-2x3 DFN

84.5

°C/W Typical 4-layer Board with

Internal Ground Plane and

2-Vias in Thermal Pad

DS22042A-page 6

MCP1603

2.0

TYPICAL PERFORMANCE CURVES

Note: The graphs and tables provided following this note are a statistical summary based on a limited number of

samples and are provided for informational purposes only. The performance characteristics listed herein are

not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified

operating range (e.g., outside specified power supply range) and therefore outside the warranted range.

Note: Unless otherwise indicated, V_IN= SHDN = 3.6V, C_OUT= C_IN= 4.7 µF, L = 4.7 µH, V_OUT(ADJ) = 1.8V, I_LOAD= 100 mA,

T_A= +25°C. Adjustable or fixed output voltage options can be used to generate the Typical Performance Characteristics.

50

49

48

47

46

45

44

43

42

41

40

52

50

48

46

44

42

40

V_OUT= 1.8V

T_A= +90^oC

V_IN= 3.6V

V_IN= 4.2V

T_A= +25^oC

V_IN= 3.0V

T_A= - 40^oC

-40 -25 -10

5

20 35 50 65 80 95 110 125

2.7 3.05 3.4 3.75 4.1 4.45 4.8 5.15 5.5

Input Voltage (V)

Ambient Temperature (^oC)

FIGURE 2-1:

I vs. Ambient Temperature.

FIGURE 2-4:

I vs. Input Voltage.

Q

100

90

100

95

V_OUT= 1.2V

V_IN= 2.7V

V_IN= 3.6V

I_OUT= 100 mA

80

70

60

50

40

30

20

90

85

80

75

70

65

60

I_OUT= 300 mA

I_OUT= 500 mA

V_IN= 4.2V

2.7 3.05 3.4 3.75 4.1 4.45 4.8 5.15 5.5

Input Voltage (V)

0.1

1

10

100

1000

Output Current (mA)

FIGURE 2-2:

(V = 1.2V).

Efficiency vs. Input Voltage

FIGURE 2-5:

(V = 1.2V).

Efficiency vs. Output Load

OUT

100

V_OUT= 1.8V

V_IN= 2.7V

V_IN= 3.6V

90

80

70

60

50

40

30

20

95

90

85

80

75

70

I_OUT= 100 mA

I_OUT= 300 mA

I_OUT= 500 mA

V_IN= 4.2V

V_OUT= 1.8V

2.7 3.05 3.4 3.75 4.1 4.45 4.8 5.15 5.5

Input Voltage (V)

0.1

1

10

100

1000

Output Current (mA)

FIGURE 2-3:

(V = 1.8V).

Efficiency vs. Input Voltage

FIGURE 2-6:

(V = 1.8V).

Efficiency vs. Output Load

OUT

DS22042A-page 7

MCP1603

Typical Performance Curves (Continued)

Note: Unless otherwise indicated, V_IN= SHDN = 3.6V, C_OUT= C_IN= 4.7 µF, L = 4.7 µH, V_OUT(ADJ) = 1.8V, I_LOAD= 100 mA,

T_A= +25°C. Adjustable or fixed output voltage options can be used to generate the Typical Performance Characteristics.

100

95

90

85

80

75

100

90

80

70

60

50

40

30

V_OUT= 2.4V

V_IN= 2.7V

V_IN= 3.6V

I_OUT= 100 mA

I_OUT= 300 mA

I_OUT= 500 mA

V_IN= 4.2V

V_OUT= 2.4V

3

3.5

4

4.5

5

5.5

0.1

1

10

100

1000

Input Voltage (V)

Output Current (mA)

FIGURE 2-7:

(V = 2.4V).

Efficiency vs. Input Voltage

FIGURE 2-10:

(V = 2.4V).

Efficiency vs. Output Load

OUT

100.0

97.5

95.0

92.5

90.0

87.5

85.0

100

V_OUT= 3.3V

90

80

70

60

50

40

30

I_OUT= 100 mA

I_OUT= 300 mA

V_IN= 3.6V

I_OUT= 500 mA

V_IN= 4.2V

V_OUT= 3.3V

3.5 3.75

4

4.25 4.5 4.75

Input Voltage (V)

5

5.25 5.5

0.1

1

10

100

1000

Output Current (mA)

FIGURE 2-8:

(V = 3.3V).

Efficiency vs. Input Voltage

FIGURE 2-11:

(V = 3.3V).

Efficiency vs. Output Load

OUT

0.6

1.82

T_A= +125 ^o

C

T_A= +90 ^o

C

V_OUT= 1.8V

1.81

1.80

1.79

1.78

1.77

1.76

1.75

1.74

0.5

0.4

0.3

0.2

0.1

I_OUT= 300 mA

T_A= +25 ^o

C

T_A= - 40 ^o

C

I_OUT= 100 mA

100 150 200 250 300 350 400 450 500

-40 -25 -10

5

20 35 50 65 80 95 110 125

Ambient Temperature (^oC)

Output Current (mA)

FIGURE 2-9:

Temperature (V

Line Regulation vs. Ambient

= 1.8V).

FIGURE 2-12:

Current (V

Output Voltage vs. Load

= 1.8V).

OUT

DS22042A-page 8

MCP1603

Typical Performance Curves (Continued)

Note: Unless otherwise indicated, V_IN= SHDN = 3.6V, C_OUT= C_IN= 4.7 µF, L = 4.7 µH, V_OUT(ADJ) = 1.8V, I_LOAD= 100 mA,

T_A= +25°C. Adjustable or fixed output voltage options can be used to generate the Typical Performance Characteristics.

2.20

2.15

2.10

2.05

2.00

1.95

2.20

2.15

2.10

2.05

2.00

1.95

-40 -25 -10

5

20 35 50 65 80 95 110 125

2.7 3.05 3.4 3.75 4.1 4.45 4.8 5.15 5.5

Input Voltage (V)

Ambient Temperature (^oC)

FIGURE 2-13:

Switching Frequency vs.

FIGURE 2-16:

Switching Frequency vs.

Ambient Temperature.

Input Voltage.

0.65

0.60

0.55

0.9

0.8

0.7

0.6

0.5

0.4

N-Channel

0.50

N-Channel

P-Channel

0.45

0.40

0.35

P-Channel

0.3

-40 -25 -10

5

20 35 50 65 80 95 110 125

2.7 3.05 3.4 3.75 4.1 4.45 4.8 5.15 5.5

Input Voltage (V)

Ambient Temperature (^oC)

FIGURE 2-14:

Switch Resistance vs. Input

FIGURE 2-17:

Switch Resistance vs.

Voltage.

Ambient Temperature.

FIGURE 2-15:

Output Voltage Startup

FIGURE 2-18:

Heavy Load Switching

Waveform.

DS22042A-page 9

MCP1603

Typical Performance Curves (Continued)

Note: Unless otherwise indicated, V_IN= SHDN = 3.6V, C_OUT= C_IN= 4.7 µF, L = 4.7 µH, V_OUT(ADJ) = 1.8V, I_LOAD= 100 mA,

T_A= +25°C. Adjustable or fixed output voltage options can be used to generate the Typical Performance Characteristics.

FIGURE 2-19:

Light Load Switching

FIGURE 2-21:

Output Voltage Line Step

Waveform.

Response vs. Time.

FIGURE 2-20:

Output Voltage Load Step

Response vs. Time.

DS22042A-page 10

MCP1603

3.0

PIN DESCRIPTIONS

The descriptions of the pins are listed in Table 3-1.

TABLE 3-1:

PIN FUNCTION TABLE

Pin No.

Description

Symbol

MCP1603 MCP1603L

2x3 DFN

TSOT23

1

2

4

2

7

V_IN

Power Supply Input Voltage Pin

8

GND

SHDN

Ground Pin

3

1

3

Shutdown Control Input Pin

4

5

4

1

V_FB/V_OUTFeedback / Output Voltage Pin

5

3

L_X

NC

EP

Switch Node, Buck Inductor Connection Pin

No Connect

—

2, 5, 6

Exposed

Pad

For the DFN package, the center exposed pad is a thermal

path to remove heat from the device. Electrically this pad is at

ground potential and should be connected to GND

3.1

Power Supply Input Voltage Pin

(V_IN)

3.4

Feedback / Output Voltage Pin

(V_FB/V_OUT

)

Connect the input voltage source to V_IN. The input

source must be decoupled to GND with a 4.7 µF

capacitor.

For adjustable output options, connect the center of the

output voltage divider to the V_FB/V_OUTpin. For fixed-

output voltage options, connect the output directly to

the V_FB/V_OUTpin.

3.2

Ground Pin (GND)

3.5

Switch Node, Buck Inductor

Connection Pin (L_X)

Ground pin for the device. The loop area of the ground

traces should be kept as minimal as possible.

Connect the L_Xpin directly to the buck inductor. This

pin carries large signal-level current; all connections

should be made as short as possible.

3.3

Shutdown Control Input Pin

(SHDN)

The SHDN pin is a logic-level input used to enable or

disable the device. A logic high (> 45% of V_IN) will

enable the regulator output. A logic-low (< 15% of V_IN)

will ensure that the regulator is disabled.

3.6

Exposed Metal Pad (EP)

For the DFN package, connect the Exposed Pad to

GND, with vias into the GND plane. This connection to

the GND plane will aid in heat removal from the

package.

DS22042A-page 11

MCP1603

4.0

4.1

DETAILED DESCRIPTION

Device Overview

4.2

Synchronous Buck Regulator

The MCP1603 is a synchronous buck regulator that

operates in a Pulse Frequency Modulation (PFM)

mode or a Pulse Width Modulation (PWM) mode to

maximize system efficiency over the entire operating

current range. Capable of operating from a 2.7V to

5.5V input voltage source, the MCP1603 can deliver

500 mA of continuous output current.

The MCP1603 has two distinct modes of operation that

allow the device to maintain a high level of efficiency

throughout the entire operating current and voltage

range. The device automatically switched between

PWM mode and PFM mode depending upon the output

load requirements.

4.2.1

FIXED FREQUENCY, PWM MODE

When using the MCP1603, the PCB area required for

a complete step-down converter is minimized since

both the main P-Channel MOSFET and the synchro-

nous N-Channel MOSFET are integrated. Also while in

PWM mode, the device switches at a constant

frequency of 2.0 MHz (typ) which allow for small filter-

ing components. Both fixed and adjustable output

voltage options are available. The fixed voltage options

(1.2V, 1.5V 1.8V, 2.5V, 3.3V) do not require an external

voltage divider which further reduces the required

circuit board footprint. The adjustable output voltage

options allow for more flexibility in the design, but

require an external voltage divider.

During heavy load conditions, the MCP1603 operates

at a high, fixed switching frequency of 2.0 MHz (typical)

using current mode control. This minimizes output rip-

ple (10 - 15 mV typically) and noise while maintaining

high efficiency (88% typical with V_IN

V_OUT= 1.8V, I_OUT= 300 mA).

= 3.6V,

During normal PWM operation, the beginning of a

switching cycle occurs when the internal P-Channel

MOSFET is turned on. The ramping inductor current is

sensed and tied to one input of the internal high-speed

comparator. The other input to the high-speed compar-

ator is the error amplifier output. This is the difference

between the internal 0.8V reference and the divided-

down output voltage. When the sensed current

becomes equal to the amplified error signal, the high-

speed comparator switches states and the P-Channel

MOSFET is turned off. The N-Channel MOSFET is

turned on until the internal oscillator sets an internal RS

latch initiating the beginning of another switching cycle.

Additionally the device features undervoltage lockout

(UVLO), overtemperature shutdown, overcurrent

protection, and enable/disable control.

PFM-to-PWM mode transition is initiated for any of the

following conditions:

• Continuous device switching

• Output voltage has dropped out of regulation

4.2.2

LIGHT LOAD, PFM MODE

During light load conditions, the MCP1603 operates in

a PFM mode. When the MCP1603 enters this mode, it

begins to skip pulses to minimize unnecessary quies-

cent current draw by reducing the number of switching

cycles per second. The typical quiescent current draw

for this device is 45 µA.

PWM-to-PFM mode transition is initiated for any of the

following conditions:

• Discontinuous inductor current is sensed for a set

duration

• Inductor peak current falls below the transition

threshold limit

DS22042A-page 12

MCP1603

4.3

Soft Start

4.6

Enable/Disable Control

The output of the MCP1603 is controlled during start-

up. This control allows for a very minimal amount of

V_OUTovershoot during start-up from V_INrising above

the UVLO voltage or SHDN being enabled.

The SHDN pin is used to enable or disable the

MCP1603. When the SHDN pin is pulled low, the

device is disabled. When pulled high the device is

enabled and begins operation provided the input

voltage is not below the UVLO threshold or a fault

condition exists.

4.4

Overtemperature Protection

Overtemperature protection circuitry is integrated in the

MCP1603. This circuitry monitors the device junction

temperature and shuts the device off, if the junction

temperature exceeds the typical 150°C threshold. If

this threshold is exceeded, the device will automatically

restart once the junction temperature drops by

approximately 10°C. The soft start is reset during an

overtemperture condition.

4.7

Undervoltage Lockout (UVLO)

The UVLO feature uses a comparator to sense the

input voltage (V_IN) level. If the input voltage is lower

than the voltage necessary to properly operate the

MCP1603, the UVLO feature will hold the converter off.

When V_INrises above the necessary input voltage, the

UVLO is released and soft start begins. Hysteresis is

built into the UVLO circuit to compensate for input

impedance. For example, if there is any resistance

between the input voltage source and the device when

it is operating, there will be a voltage drop at the input

to the device equal to I_INx R_IN. The typical hysteresis

is 140 mV.

4.5

Overcurrent Protection

Cycle-by-cycle current limiting is used to protect the

MCP1603 from being damaged when an external short

circuit is applied. The typical peak current limit is

860 mA. If the sensed current reaches the 860 mA

limit, the P-Channel MOSFET is turned off, even if the

output voltage is not in regulation. The device will

attempt to start a new switching cycle when the internal

oscillator sets the internal RS latch.

DS22042A-page 13

MCP1603

For adjustable output applications, an additional R-C

compensation network is necessary for control loop

stability. Recommended values for any output voltage

are:

5.0

5.1

APPLICATION INFORMATION

Typical Applications

The MCP1603 500 mA synchronous buck regulator

operates over a wide input voltage range (2.7V to 5.5V)

and is ideal for single-cell Li-Ion battery powered

applications, USB powered applications, three cell

NiMH or NiCd applications and 3V or 5V regulated

input applications. The 5-lead TSOT and 8-lead 2x3

DFN packages provide a small footprint with minimal

external components.

R_COMP

C_COMP

=

4.99 kΩ

33 pF

Refer to Figure 6-2 for proper placement of R_COMPand

C_COMP

.

5.4

Input Capacitor Selection

The input current to a buck converter, when operating

in continuous conduction mode, is a squarewave with

a duty cycle defined by the output voltage (V_OUT) to

input voltage (V_IN) relationship of V_OUT/V_IN. To prevent

undesirable input voltage transients, the input capacitor

should be a low ESR type with an RMS current rating

given by Equation 5.5. Because of their small size and

low ESR, ceramic capacitors are often used. Ceramic

material X5R or X7R are well suited since they have a

low temperature coefficient and acceptable ESR.

5.2

Fixed Output Voltage Applications

Typical Application Circuit shows a fixed MCP1603

in an application used to convert three NiMH batteries

into a well regulated 1.8V @ 500 mA output. A 4.7 µF

input capacitor, 4.7 µF output capacitor, and a 4.7 µH

inductor make up the entire external component solu-

tion for this application. No external voltage divider or

compensation is necessary. In addition to the fixed

1.8V option, the MCP1603 is also available in 1.2V,

1.5V, 2.5V, or 3.3V fixed voltage options.

EQUATION 5-2:

⎛

⎜

⎝

V_OUT× (V_IN– V_OUT)⎞

5.3

Adjustable Output Voltage

Applications

I_CIN,RMS= I_OUT,MAX

×

-----------------------------------------------------

⎟

V_IN

⎠

When the desired output for a particular application is

not covered by the fixed voltage options, an adjustable

MCP1603 can be used. The circuit listed in Figure 6-2

shows an adjustable MCP1603 being used to convert a

5V rail to 1.0V @ 500 mA. The output voltage is adjust-

able by using two external resistors as a voltage

divider. For adjustable-output voltages, it is

recommended that the top resistor divider value be

200 kΩ. The bottom resistor value can be calculated

using the following equation:

Table 5-1 contains the recommend range for the input

capacitor value.

5.5

Output Capacitor Selection

The output capacitor helps provide a stable output

voltage during sudden load transients, smooths the

current that flows from the inductor to the load, and

reduces the output voltage ripple. Therefore, low ESR

capacitors are a desirable choice for the output capac-

itor. As with the input capacitor, X5R and X7R ceramic

capacitors are well suited for this application.

EQUATION 5-1:

The output ripple voltage is often a design specifica-

tion. A buck converters’ output ripple voltage is a

function of the charging and discharging of the output

capacitor and the ESR of the capacitor. This ripple

voltage can be calculated by Equation 5-3.

V_FB

⎛

⎝

⎞

⎠

----------------------------

R_BOT= R_TOP

×

V_OUT– V_FB

Example:

R_TOP

V_OUT

V_FB

=

200 kΩ

EQUATION 5-3:

1.0V

0.8V

ΔI_L

ΔV_OUT= ΔI_L× ESR + --------------------

8 × f × C

R_BOT

=

200 kΩ x (0.8V/(1.0V - 0.8V))

800 kΩ

(Standard Value = 787 kΩ)

DS22042A-page 14

MCP1603

Table 5-1 contains the recommend range for the output

capacitor value.

TABLE 5-2:

MCP1603 RECOMMENDED

INDUCTORS

TABLE 5-1:

CAPACITOR VALUE RANGE

DCR

Ω

(max)

Part

Number

Value

(µH)

I_SAT

Size

C_IN

C_OUT

(A) WxLxH (mm)

Minimum

Maximum

4.7 µF

—

4.7 µF

22 µF

Coiltronics^®

SD3110

3.3

4.7

6.8

3.3

4.7

6.8

0.195 0.81

0.285 0.68

0.346 0.58

0.159 1.40

0.256 1.13

0.299 0.95

3.1x3.1x1.0

3.8x3.8x1.2

SD3110

5.6

Inductor Selection

SD3110

When using the MCP1603, the inductance value can

range from 3.3 µH to 10 µH. An inductance value of

4.7 µH is recommended to achieve a good balance

between converter load transient response and mini-

mized noise.

SD3812

Würth Elektronik^®

The value of inductance is selected to achieve a

desired amount of ripple current. It is reasonable to

assume a ripple current that is 20% of the maximum

load current. The larger the amount of ripple current

allowed, the larger the output capacitor value becomes

to meet ripple voltage specifications. The inductor

ripple current can be calculated according to the follow-

ing equation.

WE-TPC

Type XS

3.3

4.7

6.8

0.225 0.72 3.3x3.5x0.95

0.290 0.50 3.3x3.5x0.95

0.105 0.90 3.8x3.8x1.65

0.156 0.75 3.8x3.8x1.65

WE-TPC

Type XS

WE-TPC

Type S

WE-TPC

Type S

EQUATION 5-4:

Sumida^®

CMD4D06

3.3

4.7

6.8

0.174 0.77

0.216 0.75

0.296 0.62

3.5x4.3x0.8

V_OUT

⎛

⎞

⎠

-------------------

F_SW× L

ΔI_L=

× 1 – ------------

⎝

V_IN

Where:

F_SW= Switching Frequency

5.7

Thermal Calculations

The MCP1603 is available in two different packages

(TSOT-23 and 2x3 DFN). By calculating the power

dissipation and applying the package thermal

resistance, (θ_JA), the junction temperature is

estimated. The maximum continuous junction

temperature rating for the MCP1603 is +125°C.

When considering inductor ratings, the maximum DC

current rating of the inductor should be at least equal to

the maximum load current, plus one half the peak-to-

peak inductor ripple current (1/2 * ΔI_L). The inductor DC

resistance adds to the total converter power loss. An

inductor with a low DC resistance allows for higher

converter efficiency.

To quickly estimate the internal power dissipation for

the switching buck regulator, an empirical calculation

using measured efficiency can be used. Given the

measured efficiency, the internal power dissipation is

estimated by:

EQUATION 5-5:

V_OUT× I_OUT

Efficiency

⎛

⎝

⎞

⎠

------------------------------

– (V_OUT× I_OUT) = P_Diss

The difference between the first term, input power

dissipation, and the second term, power delivered, is

the internal power dissipation. This is an estimate

assuming that most of the power lost is internal to the

MCP1603. There is some percentage of power lost in

the buck inductor, with very little loss in the input and

output capacitors.

DS22042A-page 15

MCP1603

Therefore, it is important that the components along the

high current path should be placed as close as possible

to the MCP1603 to minimize the loop area.

5.8

PCB Layout Information

Good printed circuit board layout techniques are

important to any switching circuitry and switching

power supplies are no different. When wiring the high

current paths, short and wide traces should be used.

This high current path is shown with red connections in

Figure 5-1. The current in this path is switching.

The feedback resistors and feedback signal should be

routed away from the switching node and this switching

current loop. When possible ground planes and traces

should be used to help shield the feedback signal and

minimize noise and magnetic interference.

L₁

V_OUT

V_IN

4.7 µH

1.8V @ 500 mA

2.7V To 4.5V

V_IN

L_X

C_IN

4.7 µF

C_OUT

4.7 µF

V_FB

SHDN

GND

FIGURE 5-1:

PCB High Current Path.

DS22042A-page 16

MCP1603

6.0

TYPICAL APPLICATION CIRCUITS

l

L₁

4.7 µH

V_OUT

1.5V @ 500 mA

V_IN

L_X

3.0V To 4.2V

C_IN

4.7 µF

C_OUT

4.7 µF

V_FB

SHDN

GND

FIGURE 6-1:

Single Li-Ion to 1.5V @ 500 mA Application.

L₁

4.7 µH

V_OUT

1.0V @ 500 mA

V_IN

5.0V

V_IN

L_X

R_COMP

R_TOP

4.99 kΩ

C_COMP

33 pF

C_IN

4.7 µF

C_OUT

4.7 µF

200 kΩ

SHDN

V_FB

R_BOT

787 kΩ

GND

FIGURE 6-2:

5V to 1.0V @ 500 mA Application.

L₁

4.7 µH

V_OUT

1.2V @ 500 mA

V_IN

L_X

2.7V To 4.5V

C_IN

4.7 µF

C_OUT

4.7 µF

V_FB

SHDN

GND

FIGURE 6-3:

3 NiMH Batteries to 1.2V @ 500 mA Application.9

DS22042A-page 17

MCP1603

7.0

7.1

PACKAGING INFORMATION

Package Marking Information (Not to Scale)

8-Lead 2x3 DFN

Example:

Marking

Code

Part Number

MCP1603-120I/MC

MCP1603-150I/MC

MCP1603-180I/MC

MCP1603-250I/MC

MCP1603-330I/MC

MCP1603-ADJI/MC

AFM

AFK

AFJ

XXX

YWW

NNN

AFM

711

25

AFG

AFA

AFQ

5-Lead TSOT

Example

Marking

Code

Part Number

MCP1603T-120I/OS

MCP1603T-150I/OS

MCP1603T-180I/OS

MCP1603T-250I/OS

MCP1603T-330I/OS

MCP1603T-ADJI/OS

ETNN

EUNN

EVNN

EWNN

EXNN

EYNN

ET25

XXNN

Marking

Code

Part Number

MCP1603LT-120I/OS

MCP1603LT-150I/OS

MCP1603LT-180I/OS

MCP1603LT-250I/OS

MCP1603LT-330I/OS

MCP1603LT-ADJI/OS

FMNN

FKNN

EJNN

FGNN

FANN

FQNN

Legend: XX...X Customer-specific information

Y

YY

WW

NNN

Year code (last digit of calendar year)

Year code (last 2 digits of calendar year)

Week code (week of January 1 is week ‘01’)

Alphanumeric traceability code

e

3

Pb-free JEDEC designator for Matte Tin (Sn)

*

This package is Pb-free. The Pb-free JEDEC designator (

can be found on the outer packaging for this package.

)

e3

Note: In the event the full Microchip part number cannot be marked on one line, it will

be carried over to the next line, thus limiting the number of available

characters for customer-specific information.

DS22042A-page 18

MCP1603

8-Lead Plastic Dual Flat, No Lead Package (MC) – 2x3x0.9 mm Body [DFN]

Note: For the most current package drawings, please see the Microchip Packaging Specification located at

http://www.microchip.com/packaging

e

D

b

N

L

K

E2

E

EXPOSED PAD

NOTE 1

2

1

2

D2

BOTTOM VIEW

TOP VIEW

A

NOTE 2

A3

A1

Units

MILLIMETERS

Dimension Limits

MIN

NOM

8

MAX

Number of Pins

Pitch

N

e

0.50 BSC

0.90

Overall Height

Standoff

A

0.80

0.00

1.00

0.05

A1

A3

D

0.02

Contact Thickness

Overall Length

Overall Width

0.20 REF

2.00 BSC

3.00 BSC

–

E

Exposed Pad Length

Exposed Pad Width

Contact Width

Contact Length

Contact-to-Exposed Pad

D2

E2

b

1.30

1.50

0.18

0.30

0.20

1.75

1.90

0.30

0.50

–

0.25

L

0.40

K

–

Notes:

1. Pin 1 visual index feature may vary, but must be located within the hatched area.

2. Package may have one or more exposed tie bars at ends.

3. Package is saw singulated.

4. Dimensioning and tolerancing per ASME Y14.5M.

BSC: Basic Dimension. Theoretically exact value shown without tolerances.

REF: Reference Dimension, usually without tolerance, for information purposes only.

Microchip Technology Drawing C04-123B

DS22042A-page 19

MCP1603

5-Lead Plastic Thin Small Outline Transistor (OS) [TSOT]

Note: For the most current package drawings, please see the Microchip Packaging Specification located at

http://www.microchip.com/packaging

b

N

E

E1

NOTE 1

1

3

2

e

e1

D

α

A2

c

A

φ

L

A1

β

L1

Units

MILLIMETERS

Dimension Limits

MIN

NOM

MAX

Number of Leads

Lead Pitch

N

e

5

0.95 BSC

Outside Lead Pitch

Overall Height

e1

A

1.90 BSC

–

1.10

1.00

0.10

Molded Package Thickness

Standoff

A2

A1

E

0.70

0.00

0.90

–

2.80 BSC

1.60 BSC

2.90 BSC

0.45

Overall Width

Molded Package Width

Overall Length

Foot Length

E1

D

L

0.30

0.60

Footprint

L1

φ

0.60 REF

4°

Foot Angle

0°

0.08

0.30

4°

8°

Lead Thickness

Lead Width

c

–

0.20

0.50

12°

b

–

Mold Draft Angle Top

Mold Draft Angle Bottom

α

β

10°

4°

10°

12°

Notes:

1. Pin 1 visual index feature may vary, but must be located within the hatched area.

2. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.15 mm per side.

3. Dimensioning and tolerancing per ASME Y14.5M.

BSC: Basic Dimension. Theoretically exact value shown without tolerances.

REF: Reference Dimension, usually without tolerance, for information purposes only.

Microchip Technology Drawing C04-128B

DS22042A-page 20

MCP1603

APPENDIX A: REVISION HISTORY

Revision A (May 2007)

• Original Release of this Document.

DS22042A-page 21

MCP1603

NOTES:

DS22042A-page 22

MCP1603

PRODUCT IDENTIFICATION SYSTEM

To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.

Examples:

PART NO.

Device

X

XXX

X

/

XX

8-Lead DFN:

TSOT

Tape Voltage Temp. Package

a)

b)

c)

d)

e)

MCP1603-120I/MC: 1.20V Buck Reg.,

Config. and Reel

Option

8LD-DFN pkg.

MCP1603-150I/MC: 1.50V Buck Reg.,

8LD-DFN pkg.

MCP1603-180I/MC: 1.80V Buck Reg.,

8LD-DFN pkg.

Device:

MCP1603: 2.0 MHz, 500 mA Buck Regulator

Blank = Standard pinout

TSOT Pin

MCP1603-250I/MC: 2.50V Buck Reg.,

8LD-DFN pkg.

Config. Designator *

L

= Alternate pinout

* Refer to Package Types for an explanation regarding the

function of the device pins.

MCP1603-330I/MC: 3.30V Buck Reg.,

8LD-DFN pkg.

Tape and Reel:

Voltage Option:

T

=

Tape and Reel

Tube

5-Lead TSOT:

Blank

a)

b)

c)

d)

e)

f)

MCP1603T-120I/OS: 1.20V Buck Reg.,

5LD-TSOT pkg.

MCP1603T-180I/OS: 1.80V Buck Reg.,

5LD-TSOT pkg.

ADJ = Adjustable

120 = 1.20V “Standard”

150 = 1.50V “Standard”

180 = 1.80V “Standard”

250 = 2.50V “Standard”

330 = 3.30V “Standard”

MCP1603T-250I/OS: 2.50V Buck Reg.,

5LD-TSOT pkg.

MCP1603T-330I/OS: 3.30V Buck Reg.,

5LD-TSOT pkg.

MCP1603T-ADJI/OS:Adj. Buck Reg.,

5LD-TSOT pkg.

Temperature:

I

=

-40°C to +85°C

MCP1603LT-250I/OS:2.50V Buck Reg.,

5LD-TSOT pkg.

Package Type:

MC

OS

=

Plastic Dual-Flat No-Lead Package (MC), 8-Lead

Plastic Thin Small Outline Transistor (OS), 5-Lead

g)

MCP1603LT-ADJI/OS:Adj. Buck Reg.,

5LD-TSOT pkg.

DS22042A-page 23

MCP1603

NOTES:

DS22042A-page 24

Note the following details of the code protection feature on Microchip devices:

•

Microchip products meet the specification contained in their particular Microchip Data Sheet.

•

Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the

intended manner and under normal conditions.

•

There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our

knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data

Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

•

Microchip is willing to work with the customer who is concerned about the integrity of their code.

Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not

mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our

products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts

allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Information contained in this publication regarding device

applications and the like is provided only for your convenience

and may be superseded by updates. It is your responsibility to

ensure that your application meets with your specifications.

MICROCHIP MAKES NO REPRESENTATIONS OR

WARRANTIES OF ANY KIND WHETHER EXPRESS OR

IMPLIED, WRITTEN OR ORAL, STATUTORY OR

OTHERWISE, RELATED TO THE INFORMATION,

INCLUDING BUT NOT LIMITED TO ITS CONDITION,

QUALITY, PERFORMANCE, MERCHANTABILITY OR

FITNESS FOR PURPOSE. Microchip disclaims all liability

arising from this information and its use. Use of Microchip

devices in life support and/or safety applications is entirely at

the buyer’s risk, and the buyer agrees to defend, indemnify and

hold harmless Microchip from any and all damages, claims,

suits, or expenses resulting from such use. No licenses are

conveyed, implicitly or otherwise, under any Microchip

intellectual property rights.

Trademarks

The Microchip name and logo, the Microchip logo, Accuron,

dsPIC, KEELOQ, KEELOQ logo, microID, MPLAB, PIC,

PICmicro, PICSTART, PRO MATE, rfPIC and SmartShunt are

registered trademarks of Microchip Technology Incorporated

in the U.S.A. and other countries.

AmpLab, FilterLab, Linear Active Thermistor, Migratable

Memory, MXDEV, MXLAB, SEEVAL, SmartSensor and The

Embedded Control Solutions Company are registered

trademarks of Microchip Technology Incorporated in the

U.S.A.

Analog-for-the-Digital Age, Application Maestro, CodeGuard,

dsPICDEM, dsPICDEM.net, dsPICworks, ECAN,

ECONOMONITOR, FanSense, FlexROM, fuzzyLAB,

In-Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi,

MPASM, MPLAB Certified logo, MPLIB, MPLINK, PICkit,

PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal,

PowerInfo, PowerMate, PowerTool, REAL ICE, rfLAB, Select

Mode, Smart Serial, SmartTel, Total Endurance, UNI/O,

WiperLock and ZENA are trademarks of Microchip

Technology Incorporated in the U.S.A. and other countries.

SQTP is a service mark of Microchip Technology Incorporated

in the U.S.A.

All other trademarks mentioned herein are property of their

respective companies.

Printed on recycled paper.

Microchip received ISO/TS-16949:2002 certification for its worldwide

headquarters, design and wafer fabrication facilities in Chandler and

Tempe, Arizona; Gresham, Oregon and design centers in California

and India. The Company’s quality system processes and procedures

are for its PIC^®MCUs and dsPIC^®DSCs, KEELOQ^®code hopping

devices, Serial EEPROMs, microperipherals, nonvolatile memory and

analog products. In addition, Microchip’s quality system for the design

and manufacture of development systems is ISO 9001:2000 certified.

DS22042A-page 25

WORLDWIDE SALES AND SERVICE

AMERICAS

ASIA/PACIFIC

EUROPE

Corporate Office

Asia Pacific Office

Suites 3707-14, 37th Floor

Tower 6, The Gateway

Habour City, Kowloon

Hong Kong

Tel: 852-2401-1200

Fax: 852-2401-3431

India - Bangalore

Tel: 91-80-4182-8400

Fax: 91-80-4182-8422

Austria - Wels

Tel: 43-7242-2244-39

Fax: 43-7242-2244-393

2355 West Chandler Blvd.

Chandler, AZ 85224-6199

Tel: 480-792-7200

Fax: 480-792-7277

Technical Support:

http://support.microchip.com

Web Address:

www.microchip.com

Denmark - Copenhagen

Tel: 45-4450-2828

Fax: 45-4485-2829

India - New Delhi

Tel: 91-11-4160-8631

Fax: 91-11-4160-8632

France - Paris

Tel: 33-1-69-53-63-20

Fax: 33-1-69-30-90-79

India - Pune

Tel: 91-20-2566-1512

Fax: 91-20-2566-1513

Australia - Sydney

Tel: 61-2-9868-6733

Fax: 61-2-9868-6755

Atlanta

Duluth, GA

Tel: 678-957-9614

Fax: 678-957-1455

Germany - Munich

Tel: 49-89-627-144-0

Fax: 49-89-627-144-44

Japan - Yokohama

Tel: 81-45-471- 6166

Fax: 81-45-471-6122

China - Beijing

Tel: 86-10-8528-2100

Fax: 86-10-8528-2104

Italy - Milan

Tel: 39-0331-742611

Fax: 39-0331-466781

Korea - Gumi

Tel: 82-54-473-4301

Fax: 82-54-473-4302

Boston

China - Chengdu

Tel: 86-28-8665-5511

Fax: 86-28-8665-7889

Westborough, MA

Tel: 774-760-0087

Fax: 774-760-0088

Netherlands - Drunen

Tel: 31-416-690399

Fax: 31-416-690340

Korea - Seoul

China - Fuzhou

Tel: 86-591-8750-3506

Fax: 86-591-8750-3521

Tel: 82-2-554-7200

Fax: 82-2-558-5932 or

82-2-558-5934

Chicago

Itasca, IL

Tel: 630-285-0071

Fax: 630-285-0075

Spain - Madrid

Tel: 34-91-708-08-90

Fax: 34-91-708-08-91

China - Hong Kong SAR

Tel: 852-2401-1200

Fax: 852-2401-3431

Malaysia - Penang

Tel: 60-4-646-8870

Fax: 60-4-646-5086

Dallas

Addison, TX

Tel: 972-818-7423

Fax: 972-818-2924

UK - Wokingham

Tel: 44-118-921-5869

Fax: 44-118-921-5820

China - Qingdao

Tel: 86-532-8502-7355

Fax: 86-532-8502-7205

Philippines - Manila

Tel: 63-2-634-9065

Fax: 63-2-634-9069

Detroit

Farmington Hills, MI

Tel: 248-538-2250

Fax: 248-538-2260

China - Shanghai

Tel: 86-21-5407-5533

Fax: 86-21-5407-5066

Singapore

Tel: 65-6334-8870

Fax: 65-6334-8850

Kokomo

Kokomo, IN

Tel: 765-864-8360

Fax: 765-864-8387

China - Shenyang

Tel: 86-24-2334-2829

Fax: 86-24-2334-2393

Taiwan - Hsin Chu

Tel: 886-3-572-9526

Fax: 886-3-572-6459

China - Shenzhen

Tel: 86-755-8203-2660

Fax: 86-755-8203-1760

Taiwan - Kaohsiung

Tel: 886-7-536-4818

Fax: 886-7-536-4803

Los Angeles

Mission Viejo, CA

Tel: 949-462-9523

Fax: 949-462-9608

China - Shunde

Tel: 86-757-2839-5507

Fax: 86-757-2839-5571

Taiwan - Taipei

Tel: 886-2-2500-6610

Fax: 886-2-2508-0102

Santa Clara

Santa Clara, CA

Tel: 408-961-6444

Fax: 408-961-6445

China - Wuhan

Tel: 86-27-5980-5300

Fax: 86-27-5980-5118

Thailand - Bangkok

Tel: 66-2-694-1351

Fax: 66-2-694-1350

Toronto

Mississauga, Ontario,

Canada

Tel: 905-673-0699

Fax: 905-673-6509

China - Xian

Tel: 86-29-8833-7250

Fax: 86-29-8833-7256

12/08/06

DS22042A-page 26


型号：	MCP1603LT-330I/MC
厂家：	MICROCHIP
描述：	2.0 MHz, 500 mA Synchronous Buck Regulator 2.0兆赫500 mA同步降压稳压器稳压器
文件：	总26页 (文件大小：758K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

MCP1603LT-330I/MC [MICROCHIP]

相关型号：

MCP1603LT-330I/OS

MCP1603LT-ADJI/MC

MCP1603LT-ADJI/OS

MCP1603T-120I/MC

MCP1603T-120I/OS

MCP1603T-150I/MC

MCP1603T-150I/OS

MCP1603T-180I/MC

MCP1603T-180I/OS

MCP1603T-250I/MC

MCP1603T-250I/OS

MCP1603T-330I/MC