MAX17620ATA+T [MAXIM]
Switching Regulator, Current-mode, 1.8A, 4160kHz Switching Freq-Max, CMOS, PDSO8, 2 X 2 MM, ROHS COMPLIANT, TDFN-8;
| 型号： | MAX17620ATA+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Switching Regulator, Current-mode, 1.8A, 4160kHz Switching Freq-Max, CMOS, PDSO8, 2 X 2 MM, ROHS COMPLIANT, TDFN-8 开关 光电二极管 |
| 文件： | 总15页 (文件大小：823K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
General Description
Benefits and Features
● Minimizes External Components, Reducing Total
The MAX17620 is a high-frequency, high-efficiency
synchronous step-down DC-DC converter with integrated
MOSFETs that operates over a 2.7V to 5.5V input voltage
range. The device supports up to 600mA load current and
Cost
• Synchronous Operation for High Efficiency and
Reduced Cost
• Internal Compensation for Stable Operation at Any
Output Voltage
1.5V to 100% V output voltage. High-frequency operation
enables the use of small, low-cost inductors and capacitors.
IN
• All-Ceramic Capacitor Solution
• 4MHz Operation
The device features selectable PWM/skip mode of
operation at light loads and operates at a 4MHz fixed-
frequency in PWM mode. Skip mode improves system
efficiency at light loads, while PWM mode maintains a
constant switching frequency over the entire load.
In skip mode, the device draws only 40µA of quiescent
current from the supply input. In shutdown mode, the current
consumption is reduced to 0.1µA.
The device also features a soft-start feature to reduce
the inrush current during startup, and also incorporates an
enable (EN) pin to turn on/off the device. An open-drain
PGOOD pin provides power-good signal to the system
upon achieving successful regulation of the output voltage.
• Only 5 External Components Required
2
• Total Solution Size is 12mm (Sum of the
Components Area)
● Reduces Number of DC-DC Regulators to Stock
• Wide 2.7V to 5.5V Input Voltage Range
• Adjustable 1.5V to 100% V Output Voltage Range
IN
• Delivers Up to 600mA Load Current
• 100% Duty-Cycle Operation
• +1%/-0.75% Reference Voltage Accuracy
• Available in a 2mm x 2mm TDFN Package
● Reduces Power Dissipation
• Peak Efficiency 91%
• Skip Mode for High Light-Load Efficiency
• Shutdown Current = 0.1µA
● Operates Reliably
The MAX17620 is available in an 8-pin, 2mm x 2mm
TDFN package and operates over the -40°C to +125°C
temperature range.
Applications
• Peak Current-Limit Protection
• Soft-Start Reduces Inrush Current During Startup
• Built-In Output-Voltage Monitoring
(Open-Drain PGOOD Pin)
● Point-of-Load Power Supply
● Standard 5V Rail Supplies
● Battery-Powered Instruments
● Distributed Power Systems
• -40°C to +125°C Operation
Ordering Information appears at end of data sheet.
Typical Application Circuit—1.8V, 600mA Step-Down Regulator
L
1µH
2.7V TO 5.5V
VOUT
1.8V/600mA
IN
LX
CIN
2.2µF
MAX17620
COUT
10µF
R1
24kΩ
GND
VOUT
FB
PGOOD
EN
R2
19.1kΩ
MODE
CIN: 2.2µF/10V/0603/X7R,GRM188R71A225KE15D, MURATA
L1: 1μH, 60mΩ, MAKK2016H1ROM, TAIYO-YUDEN
COUT: 10μF/6.3V/0805/X7R, GRM21BR70J106KE76K, MURATA
19-7543; Rev 3; 7/16
MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
Absolute Maximum Ratings
IN to GND..................................................................-0.3V to 6V
LX to GND.................................................................-0.3V to 6V
MODE ..........................................................-0.3V to V + 0.3V
Operating Temperature Range......................... -40°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range............................ -65°C to +150°C
Soldering Temperature (Reflow)......................................+260°C
IN
EN, PGOOD, FB, V
to GND..............................-0.3V to 6V
Continuous Power Dissipation (up to T = +70°C)
OUT
A
(derate 9.8mW/°C above T = +70°C).........................784.3mW
A
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
(Note 1)
Package Thermal Characteristics
TDFN
Junction-to-Ambient Thermal Resistance (θ ) ........102°C/W
Junction-to-Case Thermal Resistance (θ ).................8°C/W
JC
JA
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
Electrical Characteristics
V
= +3.6V, T = T = -40°C to +125°C, unless otherwise noted. Typical specifications are at T = T = +25°C. (Note 2)
IN
A
J
A
J
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
INPUT SUPPLY (IN)
Input Voltage Range
V
2.7
5.5
V
IN
I
V
= 0V, shutdown mode
0.1
40
6
IN-SH
EN
µA
Input Supply Current
I
Nonswitching
Q_SKIP
I
PWM mode (switching)
mA
V
Q-PWM
Undervoltage-Lockout Threshold
(UVLO)
V
V
rising
2.55
2.6
2.65
IN_UVLO
IN_UVLO_HYS
IN
UVLO Hysteresis
ENABLE (EN)
V
200
mV
EN Low Threshold
V
V
V
falling
rising
0.8
50
V
V
EN_LOW
EN
EN
EN High Threshold
EN Hysteresis
V
2
EN_HIGH
V
220
10
mV
nA
EN_HYS
EN Input Leakage
I
V
= 5.5V, T = T = +25°C
EN A J
EN
POWER MOSFETS
High-Side pMOS On-Resistance
R
V
V
V
V
= 3.6V, I = 190mA
120
100
80
200
160
145
130
1
mΩ
mΩ
mΩ
mΩ
µA
DS-ONH
IN
IN
IN
IN
LX
High-Side pMOS On-Resistance
Low-Side nMOS On-Resistance
Low-Side nMOS On-Resistance
LX Leakage Current
R
= 5.0V, I = 190mA
LX
DS-ONH
R
= 3.6V, I = 190mA
LX
DS-ONL
DS-ONL
LX_LKG
R
= 5.0V, I = 190mA
70
LX
I
LX = GND or IN, T = +25°C
A
0.1
High-Side Peak Current Limit
Low-Side Valley Current Limit
Low-Side Negative Current Limit
I
1150
1450
1170
1050
1800
1450
mA
mA
mA
LIM_PEAK
I
920
LIM_VALLEY
I
Current entering into LX pin
LIM_NEG
Low-Side Zero-Crossing
Current Limit
MODE = IN, current leaving out of LX
pin
I
100
mA
LIM_ZX
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MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
Electrical Characteristics (continued)
V
= +3.6V, T = T = -40°C to +125°C, unless otherwise noted. Typical specifications are at T = T = +25°C. (Note 2)
IN
A
J
A
J
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SWITCHING FREQUENCY
Switching Frequency
Minimum Controllable On-Time
LX Dead Time
f
MODE = GND
3.84
4
40
3
4.16
MHz
ns
SW
t
ON_MIN
ns
Soft-Start Time
t
t
= 4096 CLK cycles
SS
1
ms
SS
FEEDBACK (FB)
FB Voltage Accuracy
FB Input Bias Current
POWER GOOD (PGOOD)
PGOOD Rising Threshold
PGOOD Falling Threshold
PGOOD Output Low
PGOOD Output Leakage Current
MODE
V
PWM mode
FB = 0.6V, T = T = 25°C
-0.75
+1
%
FB
I
50
120
nA
FB
A
J
FB rising
FB falling
91.5
93.5
90
95.5
92
%
%
88
I
= 5mA
200
100
mV
nA
PGOOD
I
PGOOD = 5.5V, T = T = 25°C
A J
PGOOD_LKG
MODE Pullup Current
THERMAL SHUTDOWN
V
= GND
5
µA
MODE
Thermal-Shutdown Rising
Threshold
Temperature rising
165
10
°C
°C
Thermal-Shutdown Hysteresis
Note 2: Limits are 100% production tested at T = +25°C. Limits over the operating temperature range and relevant supply voltage
A
range are guaranteed by design and characterization.
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MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
Typical Operating Characteristics
(See the Typical Application Circuits, T = +25°C, V = 3.6V, unless otherwise noted.)
A
IN
1.8V OUTPUT, SKIP MODE,
EFFICIENCY vs. LOAD CURRENT
1.8V OUTPUT, PWM MODE,
LOAD AND LINE REGULATION
1.8V OUTPUT, PWM MODE,
EFFICIENCY vs. LOAD CURRENT
100
95
90
85
80
75
70
65
60
100
1.810
1.805
1.800
1.795
1.790
VIN = 5.5V
95
90
85
80
75
70
VIN = 3.6V
VIN = 5.5V
VIN = 4.2V
VIN = 3.6V
VIN = 2.7V
VIN = 5.5V
VIN = 2.7V
VIN = 4.2V
VIN = 4.2V
VIN = 3.6V
VIN = 2.7V
MODE = OPEN
100
MODE = GND
450 550
MODE = GND
500 600
600
1
10
50
150
250
350
0
100
200
300
400
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
INPUT SUPPLY CURRENT vs.
TEMPERATURE, SKIP MODE
1.8V OUTPUT, SKIP MODE,
LOAD AND LINE REGULATION
FEEDBACK VOLTAGE vs. TEMPERATURE
810
808
806
804
802
800
798
796
794
792
790
60
55
50
45
40
35
30
1.830
1.825
1.820
1.815
1.810
1.805
1.800
1.795
1.790
VIN = 5.5V
VIN = 3.6V
VIN = 2.7V
VIN = 5.5V
VIN = 3.6V
VIN = 2.7V
VIN = 4.2V
300
MODE = OPEN
400 500
-40 -20
0
20 40 60 80 100 120
TEMPERATURE (°C)
-40 -20
0
20 40 60 80 100 120
0
100
200
600
TEMPERATURE (°C)
LOAD CURRENT (mA)
SOFT-START FROM EN, PWM MODE,
1.8V OUTPUT, NO LOAD CURRENT
SHUTDOWN CURRENT vs. TEMPERATURE
70
60
50
40
30
20
10
0
VEN
5V/div
1V/div
VIN = 5.5V
VOUT
VIN = 3.6V
VIN = 2.7V
VPGOOD
IOUT
2V/div
200mA/div
-10
-40 -20
0
20 40 60 80 100 120
200μs/div
TEMPERATURE (°C)
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MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
Typical Operating Characteristics (continued)
(See the Typical Application Circuits, T = +25°C, V = 3.6V, unless otherwise noted.)
IN
A
SOFT-START WITH 1V PREBIAS,
1.8V OUTPUT, PWM MODE
SOFT-START/SHUTDOWN FROM EN,
1.8V OUTPUT, 600mA LOAD CURRENT
STEADY-STATE SWITCHING WAVEFORMS,
1.8V OUTPUT, NO LOAD, PWM MODE
VOUT
(AC)
10mV/div
VEN
5V/div
1V/div
VEN
5V/div
VOUT
VOUT
1V/div
2V/div
VLX
IIN
200mA/div
2V/div
VPGOOD
2V/div
200mA/div
ILX
VPGOOD
1ms/div
100ns/div
200μs/div
1.8V OUTPUT, PWM MODE,
(LOAD CURRENT STEPPED
FROM NO LOAD TO 300mA)
STEADY-STATE SWITCHING WAVEFORMS,
1.8V OUTPUT, 10mA LOAD, SKIP MODE
STEADY-STATE SWITCHING WAVEFORMS,
1.8V OUTPUT, 600mA LOAD CURRENT
VOUT
(AC)
VOUT
(AC)
10mV/div
20mV/div
VOUT
(AC)
20mV/div
2V/div
VLX
ILX
2V/div
VLX
500mA/div
ILX
IOUT
200mA/div
500mA/div
100ns/div
4µs/div
40μs/div
1.8V OUTPUT,
(LOAD CURRENT STEPPED
FROM 300mA TO 600mA)
1.8V OUTPUT, SKIP MODE,
(LOAD CURRENT STEPPED
FROM 5mA TO 300mA)
VOUT
(AC)
VOUT
(AC)
50mV/div
20mV/div
IOUT
IOUT
200mA/div
200mA/div
40μs/div
40µs/div
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MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
Typical Operating Characteristics (continued)
(See the Typical Application Circuits, T = +25°C, V = 3.6V, unless otherwise noted.)
A
IN
1.8V OUTPUT, SKIP MODE,
(LOAD CURRENT STEPPED
FROM 5mA TO 50mA)
OVERLOAD PROTECTION, 1.8V OUTPUT
VOUT
1V/div
VOUT
(AC)
20mV/div
IOUT
IOUT
500mA/div
50mA/div
400µs/div
40µs/div
BODE PLOT
TOC19
GAIN
PHASE
FCR = 189KHz,
PHASE MARGIN = 62°
FREQUENCY(Hz)
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MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
Pin Configuration
TOP VIEW
PGOOD
5
LX
8
VOUT
7
FB
6
MAX17620
+
1
2
3
4
IN
GND
EN
MODE
TDFN
(2mm x 2mm)
Pin Description
PIN
NAME
FUNCTION
Power Supply Input. Connect a minimum 1µF ceramic capacitor from IN to GND for bypassing high-
frequency noise on IN pin to ground.
1
IN
2
GND
EN
Ground Pin. Connect to system ground.
Enable Input. Logic-high voltage on EN pin enables the device, while logic-low voltage disables the
device.
3
PWM or Skip Mode Selection Input. Connect the MODE pin to GND to enable PWM mode operation.
Leave the MODE pin unconnected to enable skip mode operation.
4
5
6
MODE
PGOOD
FB
Open-Drain Power Good Output. Connect PGOOD pin to output voltage or IN pin through an external
pullup resistor to generate a “high” level if the output voltage is above 93% of the target regulated
voltage. If not used, leave this pin unconnected. The PGOOD is driven low if the output voltage is below
90% of the target regulated voltage.
Feedback Input. Connect FB to the center of the external resistor-divider from output to GND to set the
output voltage.
7
8
VOUT
LX
Output Voltage Input. Connect the positive terminal of the output voltage to the VOUT pin.
Switching Node. Connect LX pin to the switching node of the inductor.
Exposed Pad. Connect exposed pad to the system ground.
—
EP
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MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
Block Diagram
IN
MAX17620
POK
UVLO
HIGH-SIDE
BANDGAP
CURRENT SENSE
LOGIC
EN
HSCS
HSLIM
IPFM
CHIPEN
2V
THSD
THERMAL
SHUTDOWN
DRIVER
LOGIC
LX
IN
CLK
OSCILLATOR
CONTROL
LOGIC
5µA
ZX
MODE
LSCS
PFM_EN
CHIPEN
0.55 x VIN
LSLIM
LOW SIDE
CURRENT SENSE
LOGIC
SKIP PWM
VOUT
GND
SLOPE
COMPENSATION
PFM_EN
SKIP
PGOOD
SLOPE
FB
VREF
HSCS
PWM
0.748V
FB
ERROR
AMPLIFIER
VREF
CLK
SOFT
START
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MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
Mode Selection (MODE)
Detailed Description
The device can be set to operate in either PWM mode
or skip mode under light-load conditions by connecting
the MODE pin to ground or leaving it unconnected.
Connecting the MODE pin to ground sets the device to
PWM mode and leaving it unconnected sets the device
to skip mode.
The MAX17620 is a high-frequency, high-efficiency
synchronous step-down DC-DC converter with integrated
MOSFETs that operates over a 2.7V to 5.5V input voltage
range. The device supports up to 600mA load current
and 1.5V to 100% V output voltage. High-frequency
IN
operation allows the use of small, low-cost inductors and
capacitors.
In PWM mode, the device operates with its nominal
switching frequency of 4MHz over the entire load current
range and the inductor current is allowed to go negative.
PWM mode is useful in applications where constant
switching frequency is desired.
The device features a MODE pin to set the device to operate in
PWMorskipmodeunderlight-loadconditions.InPWMMode,the
deviceoperateswithitsnominal switching frequency of 4MHz
overentireloadcurrentrange.Inskipmode,thedeviceskips
some cycles at light loads thereby reducing the switching
frequency and achieving high efficiency. The device
features a soft-start, open-drain power-good signal
(PGOOD) and enable input (EN).
In skip mode, the device skips pulses at light loads for
high efficiency and the inductor current is not allowed to
go negative. In this mode, when the output voltage falls
below the target value, the internal high-side MOSFET
is turned on until the inductor current reaches to peak
current threshold in skip mode. Once the high-side FET is
turned off, the low-side FET is turned on until the inductor
current falls to zero. The device enters into PWM mode if
the output voltage is below the target voltage during the
next 3 clock cycles after the inductor current falls to zero. If
the output voltage is above the target value during the next
3 clock cycles, then both the high-side and low-side FETs
are turned off and the device enters hibernation mode until
the load discharges the output below the target value.
Control Architecture
The device uses an internally compensated, peak-
current-mode-control architecture. The high-side MOSFET
is turned on at each clock edge and the low-side MOSFET
is turned off. The high-side MOSFET remains on until the
sum of the high-side MOSFET current-sense voltage and
the internal slope compensating ramp voltage hits the
control voltage generated by the error amplifier. At this
moment, the high-side MOSFET is turned off and the low-
side MOSFET is turned on.
The peak current threshold in skip mode is a function
of the output inductor and is (375/L)mA, where L is the
output inductor value in µH. The advantage of the skip
mode is higher efficiency at light loads because of lower
quiescent current drawn from the supply. The disadvantage
is that the output-voltage ripple is higher compared
to that of the PWM mode operation and the switching
frequency is not constant at light loads. The device
always operates in skip mode during soft-start under light
loads independent of the MODE pin status. The peak
current threshold in skip mode during soft-start is reduced
to 50% of the value during steady-state operation.
During the high-side MOSFET on-time, the inductor
current ramps up and stores energy. During the low-side
MOSFET on-time, the inductor current ramps down and
releases the stored energy to the output.
Enable Input (EN)
The device is enabled by setting the EN pin to a logic-
high. Accordingly, a logic-low disables the device. When
the device is enabled, an internal soft-start circuitry
monotonically ramps up the error amplifier’s reference
voltage from 0 to 0.8V in fixed soft-start time of 1ms. This
causes the output voltage to ramp monotonically from 0V
to set voltage. It also avoids excessive inrush current and
prevents excessive voltage drop of batteries with high
internal impedance.
Driving EN low disables the switching and output is
discharged with a typical discharge resistor of 225Ω. The
same happens when the device gets disabled by thermal
shutdown or undervoltage-lockout trigger.
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MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
Power-Good Indicator (PGOOD)
Undervoltage Lockout
The device includes an open-drain power good output
that indicates the output voltage status. PGOOD goes
high impedance when the output voltage is above 93.5%
of the target value, and goes low when the output voltage
is below 90% of the target value.
The device features an integrated input undervoltage
lockout (UVLO) feature that turns the device on/off based
on the voltage at the IN pin. The device turns on if the IN
pin voltage is higher than the UVLO threshold (V
)
IN_UVLO
of 2.6V (typ) (assuming EN is at logic-high) and turns off
when the IN pin voltage is 200mV (V ) below
IN_UVLO_HYS
Startup Into a Prebiased Output
the V
.
IN_UVLO
The device is capable of soft-starting into a prebiased
output without discharging the output. The device
ramps up the output voltage monotonically from the
prebiased level to the target level during the soft-start
period if the prebiased voltage is less than the target
output voltage. If the prebiased voltage is more than the
target output voltage, no switching happens during the
soft-start period. The device operation after the completion
of the soft-start period under prebiased output condition
(where the prebiased voltage is higher than the target
output voltage) depends on the PWM/skip mode. In PWM
Mode, the device tries to regulate the output voltage to the
target level by sinking current from the prebiased source.
In skip mode, the device does not initiate switching until
the output voltage falls below the target output voltage.
Overcurrent Protection
The device features a robust overcurrent-protection
scheme that protects the device and inductor under
overload and output short-circuit conditions. A cycle-by-
cycle peak current limit turns off the high-side MOSFET
and turns on the low-side MOSFET whenever the high-
side MOSFET current exceeds the internal peak current
limit of 1.45A (typ). The low-side MOSFET remains on
until the next clock cycle. The high-side MOSFET is
turned on again, if the inductor current is less than the
valley current limit at the next clock rising edge. Otherwise,
the low-side MOSFET is kept on for the next clock cycle
as well. Under severe overload conditions, the current will
not exceed 1.45A. If the overload condition is removed,
the part recovers smoothly to target output voltage with no
overshoot.
100% Duty-Cycle Operation
The device can provide 100% duty-cycle operation. In
this mode, the high-side switch is constantly turned on,
while the low-side switch is turned off. This is particularly
useful in battery-powered applications to achieve longest
operation time by taking full advantage of the whole
battery-voltage range. The minimum input voltage to
maintain the output-voltage regulation can be calculated
as:
Thermal Shutdown
Thermal-shutdown protection limits the total power
dissipation in the device. When the device junction
temperature exceeds +165°C, an on-chip thermal
sensor shuts down the device, allowing it to cool. The
thermal sensor turns the device on again after the junction
temperature cools by 10°C.
V
= V
+ (I
x R
)
IN_MIN
OUT
OUT
ON
where,
V
V
is the minimum input voltage
IN_MIN
is the target output voltage
OUT
OUT
I
is the load current
R
is the sum of the high-side FET on-resistance and
ON
the output inductor DCR
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MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
Output Capacitor Selection
Applications information
X7R ceramic capacitors are preferred as output capaci-
tors due to their stability over temperature in industrial
Inductor Selection
Three key inductor parameters must be specified to select
output inductor:
applications. The device’s internal loop-compensation
parameters are optimized for 10µF output capacitors. The
device requires a minimum of 10µF (typ) capacitance for
stability. Table 2 lists the recommended output capacitors.
Capacitors rated less than 4V can be selected for output
voltages less than 3V.
1) Inductor value
2) Inductor saturation current
3) DC resistance of the Inductor
The device’s internal slope compensation and current
limit are optimized for 1µH output inductor. Select 1µH
inductor with a saturation current rating higher than the
maximum peak current limit of 1.9A. Inductor with low
DC resistance improves the efficiency of the system.
Selecting ferrite-cored inductors reduces the core losses
and improves efficiency. Table 1 lists recommended
inductors for use in designs.
Table 1. List of Recommended Inductors
CURRENT
RATING
(A)
DC RESISTANCE
(TYP)
DIMENSIONS
INDUCTANCE
L x W x H
PART NUMBER
MANUFACTURER
(µH)
3
(mΩ)
(mm )
1
1
2.6
3.2
37
50
2.5 x 2 x 1.2
2.5 x 2 x 1
IFSC1008ABER1R0M01
252010CDMCDS-1R0MC
Vishay Dale
Sumida
Samsung
Electro-Mechanics
America
1
2.3
48
2.5 x 2 x 0.9
CIG22E1R0MNE
1
1
2.3
2.7
48
60
2.5 x 2 x 1.2
2 x 1.6 x 1
MLP2520K1R0MT0S1
MAKK2016H1ROM
TDK Corporation
Taiyo Yuden
Table 2. List of Recommended Output Capacitors
CAPACITANCE
DIELECTRIC
TYPE
VOLTAGE RATING
(V)
PART
NUMBER
PACKAGE
MANUFACTURER
(µF)
10
10
10
X7R
X7R
X7R
6.3
6.3
6.3
0805
0805
0805
C2012X7R0J106K125AB
GRM21BR70J106KE76K
JMK212B7106KG-T
TDK Corporation
Murata Americas
Taiyo Yuden
Maxim Integrated
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MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
particular operating condition, the power losses that lead
to the temperature rise of the device are estimated as
follows:
Input Capacitor Selection
The input filter capacitor reduces peak current drawn from
the power source and reduces noise and voltage ripple
on the input caused by the circuit’s switching. The input
1
2
P
= P
x
−1 − I
xR
OUT DCR
capacitor RMS current (I
equation:
) is defined by the following
RMS
)
LOSS
OUT
(
η
where,
V
x(V − V
)
OUT
OUT
IN
I
= I
x
OUT(MAX)
RMS_CIN
P
is the output power given by the following equation:
OUT
V
IN
P
V
x I
OUT = OUT OUT
where:
See the Typical Operating Characteristics for the power-
conversion efficiency or measure the efficiency to deter-
mine the total power losses.
I
is the maximum load current
OUT(MAX)
V
is the input voltage
IN
V
is the output voltage
OUT
The junction temperature (T ) of the device can be
J
Use low-ESR ceramic capacitors as the input capaci-
tor. X7R temperature coefficient capacitors are recom-
mended in industrial applications for their stability over
temperature. Calculate the input capacitor value using the
following equation:
estimated at any ambient temperature (T ) from the
following equation:
A
T
T + (θ x P
)
LOSS
J =
A
JA
where θ is the junction-to-ambient thermal resistance
JA
of the package (102°C/W for a four-layer board measured
using JEDEC specification JESD51-7).
I
x V
x(V − V
)
OUT
OUT(MAX)
OUT
IN
C
=
IN
2
η x f
x ∆V x V
IN IN
SW
If the application has a thermal-management system that
ensures the exposed pad of the device is maintained at a
where:
is the switching frequency (= 4MHz)
given temperature (T ), the junction temperature can be
EP
f
SW
estimated using the following formula:
η is the efficiency
T
T
+ (θ x P
)
LOSS
J = EP
JC
In applications where the input source is located distant
from the device input, an electrolytic capacitor should
be added in parallel to the ceramic capacitor to provide
necessary damping for potential oscillations caused by
the inductance of the longer input cable and the ceramic
capacitor.
where θ is the junction-to-case thermal resistance of
the device (8°C/W)
JC
V
OUT
Adjusting the Output voltage
The MAX17620 supports output voltages from 1.5V to
100% V . Set the output voltage with a resistor-divider
IN
MAX17620
R1
R2
connected from the positive terminal of the output voltage
to the ground (see Figure 1). Choose R2 in the range of
10kΩ to 100kΩ and calculate the R1 using the following
equation:
FB
OUT
.8
R1= R2 x
−1
GND
Power Dissipation
Ensure that the junction temperature of the device does
not exceed +125°C under the operating conditions. At a
Figure 1. Adjusting the Output Voltage
Maxim Integrated
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MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
For a sample PCB layout that ensures first-pass success,
refer to the MAX17620 evaluation kit layout available at
http://www.maximintegrated.com
PCB Layout Guidelines
Careful PCB layout is critical to achieve clean and stable
operation. In particular, the traces that carry pulsating current
should be short and wide so that the parasitic inductance
formed by these traces can be minimized. Follow the
following guidelines for good PCB layout.
● Place the input capacitor as close as possible to the
IN and GND pins. Use a wide trace to connect the
input capacitor to the IN and GND pins to reduce the
trace inductance.
●
Minimize the area formed by the LX pin and the inductor
connection to reduce the radiated EMI.
Ensure that all the feedback connections are short.
Route the LX node away from the FB, VOUT and
MODE pins.
●
●
Typical Application Circuit
L
1µH
2.7V TO 5.5V
VOUT
1.8V/600mA
IN
LX
CIN
2.2µF
MAX17620
COUT
10µF
R1
24kΩ
GND
VOUT
FB
PGOOD
EN
R2
19.1kΩ
MODE
CIN: 2.2µF/10V/0603/X7R,GRM188R71A225KE15D, MURATA
L1: 1μH, 60mΩ, MAKK2016H1ROM, TAIYO-YUDEN
COUT: 10μF/6.3V/0805/X7R, GRM21BR70J106KE76K, MURATA
Figure 2. 1.8V, 600mA Step-Down Regulator
Maxim Integrated
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MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
Ordering Information
Chip Information
PROCESS: CMOS
PART
TEMP RANGE
PIN-PACKAGE
8 TDFN
MAX17620ATA+T
-40°C to +125°C
Package Information
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.com/packages. Note
that a “+”, “#”, or “-” in the package code indicates RoHS status
only. Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
8 TDFN
T822+3C
21-0168
90-0065
Maxim Integrated
│ 14
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MAX17620
4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
Revision History
REVISION REVISION
PAGES
DESCRIPTION
CHANGED
NUMBER
DATE
0
3/15
Initial release
—
Updated MODE pin description, updated global specifications for the Typical
Operating Characteristics section, and updated table 1 and table 2
1
6/15
4–6, 7, 9, 11
Updated Typical Applications Circuit, replaced/added plots in Typical Operating
Characteristics section, and updated Block Diagram
2
3
10/15
7/16
1-6, 8, 10–11, 13
Fixed minor text errors
9, 11
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
©
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
2016 Maxim Integrated Products, Inc.
│ 15
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