MP1527DR-Z [MPS]
Switching Regulator, Current-mode, 2A, 1300kHz Switching Freq-Max, PQCC16, 4 X 4 MM, QFN-16;
| 型号： | MP1527DR-Z |
| 厂家： | 
MONOLITHIC POWER SYSTEMS |
| 描述： | Switching Regulator, Current-mode, 2A, 1300kHz Switching Freq-Max, PQCC16, 4 X 4 MM, QFN-16 转换器 升压转换器 |
| 文件： | 总14页 (文件大小：269K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MP1527
2A, 1.3MHz
Step-Up Converter
Monolithic Power Systems
General Description
Features
The MP1527 is a 2A, fixed frequency step-up
converter in a tiny 16 lead QFN package. The
high 1.3MHz switching frequency allows for
smaller external components producing a
compact solution for medium-to-high current
step-up, flyback, and SEPIC applications.
2A Peak Current Limit
Internal 150mΩ Power Switch
VIN Range of 2.6V to 25V
>93% Efficiency
Zero Current Shutdown Mode
Under Voltage Lockout Protection
Timer-Latch Fault Detection
Soft Start Operation
The MP1527 regulates the output voltage up
to 25V at efficiency as high as 93%. Soft-start,
timer-latch fault circuitry, cycle-by-cycle current
limiting, and input undervoltage lockout
prevent overstressing or damage to external
circuitry at startup and output short-circuit
conditions. Fixed frequency operation eases
control of noise making the MP1527 optimal
for noise sensitive applications such as mobile
handsets and wireless LAN PC cards.
Thermal Shutdown
Tiny 4mm x 4mm 16 pin QFN Package
Evaluation Board Available
Applications
SOHO Routers, PCMCIA Cards, Mini PCI
Handheld Computers, PDAs
Cell Phones, Digital and Video Cameras
Small LCD Display
Current-mode
regulation
and
external
compensation components allow the MP1527
control loop to be optimized over wide variety
of input voltage, output voltage and load
current conditions.
Ordering Information
Part Number
MP1527DR
MP1527DM
EV0034
Package
QFN16 (4x4)
TSSOP14
Temperature
-40° to +85°C
-40° to +85°C
The MP1527 is offered in a tiny 4mm x 4mm
16 lead QFN and 14 lead TSSOP packages.
MP1527DR Evaluation Board
∗
For Tape & Reel, add suffix –Z (e.g. MP1527DR–Z)
For Lead Free, add suffix –LF (e.g. MP1527DR–LF–Z)
Figure 1: Typical Application Circuit
VIN = 2.6V to 25V
IN
FAULT
EN
SW
FAULT
VOUT = 3.3V to 25V
ON/OFF
SS
BP
FB
COMP
PGND
SGND
MP1527 Rev 1.8_8/31/05
Monolithic Power Systems, Inc.
1
MP1527
2A, 1.3MHz
Step-Up Converter
Monolithic Power Systems
Absolute Maximum Ratings (Note 1)
Recommended Operating Conditions
IN Input Supply Voltage VIN
Step Up Output Voltage
Operating Temperature
2.6V to 25V
3.3V to 25V
Input Supply Voltage VIN
SW Pin Voltage VSW
-0.3V to 27V
-0.3V to 27V
-40°C to +85°C
Voltage at All Other Pins
Storage Temperature
-0.3V to 6V
-55°C to +150°C
Package Thermal Characteristics
Thermal Resistance ΘJA (TSSOP14)
90°C/W
Thermal Resistance ΘJA (QFN16) (Note 2)
46°C/W
Electrical Characteristics (VIN = 5.0V, TA = 25°C unless specified otherwise)
Parameters
Conditions
Min
Typ
Max
Units
IN Shutdown Supply Current
IN Operating Supply Current
BP Output Voltage
IN Undervoltage Lockout Threshold
IN Undervoltage Lockout Hysteresis
EN Input Low Voltage
VEN<0.3V
0.5
0.9
2.4
1.0
1.2
µA
mA
V
V
mV
V
VEN>2V, VFB=1.1V
VIN = 2.6V to 25V
VIN Rising
2.1
1.5
2.4
0.3
100
EN Input High Voltage
V
EN Input Hysteresis
EN Input Bias Current
100
100
1.3
90
400
300
30
1.22
-100
2
mV
nA
MHz
%
V/V
µA/V
µA
V
SW Switching Frequency
SW Maximum Duty Cycle
Error Amplifier Voltage Gain
Error Amplifier Transconductance
COMP Maximum Output Current
FB Regulation Threshold
FB Input Bias Current
1.0
85
1.5
VFB = 1.1V
Sourcing and Sinking
1.196
1.244
VFB=1.22V
During Soft-Start
nA
µA
SS Charging Current
1.2
0.2
V
FAULT Input Threshold Voltage
V
FB < 1.0V
V
FAULT Output Low Voltage
SW On Resistance
VIN =5V
VIN =3V
(Note 3)
VSW = 25V
150
225
3.0
0.5
160
mΩ
mΩ
A
µA
°C
SW Current Limit
SW Leakage Current
Thermal Shutdown
2.0
Note 1: Exceeding these ratings may damage the device.
Note 2: Measured on approximately 1” square of 1oz copper.
Note 3: Guaranteed by design. Not tested.
MP1527 Rev 1.8_8/31/05
Monolithic Power Systems, Inc.
2
MP1527
2A, 1.3MHz
Step-Up Converter
Monolithic Power Systems
Pin Descriptions
NC
NC
IN
1
2
3
4
5
6
7
14
13
12
11
10
9
SGND
EN
BP
NC
COMP
FB
12
11
10
9
1
2
3
4
COMP
NC
PGND
PGND
SW
SW
Top
View
PGND
SGND
FAULT
BP
8
SS
EN
SW
Table 1: Pin Description
QFN
Pin
TSSOP
Pin
Name
Function
Compensation Node. COMP is the output of the internal transconductance error
amplifier. Connect a series RC network from COMP to SGND to compensate the
regulator control loop.
1
10
COMP
2, 6, 7
3
1, 2, 11
12
NC
BP
No Connect
Output of the internal 2.4V low dropout regulator. Connect a 10nF bypass
capacitor between BP and SGND. Do not apply an external load to BP.
Regulator On/Off Control Input. A logic high input (VEN>1.5V) turns on the
regulator, a logic low puts the MP1527 into low current shutdown mode.
4
13
EN
5, 13
8
6, 14
3
SGND
IN
Signal Ground
Input Supply
Output Switching Node. SW is the drain of the internal n-channel MOSFET.
Connect the inductor and rectifier to SW to complete the step-up converter.
9, 10
4
5
SW
11, 12
PGND
Power Ground
Fault Input/Output.
detected a fault and shuts the regulator off once a fault is indicated. Connect the
input/outputs together for all MP1527 regulators to force all regulators off
is an Input/Output that indicates that the MP1527
FAULT
FAULT
when any one regulator detects a fault. Once a fault is detected, cycle EN or the
input power to restart the regulator. Pull to the input voltage through a
14
7
FAULT
FAULT
input/outputs can be connected in parallel.
100kΩ resistor. Up to 20
FAULT
Soft-Start Input. Connect a 10nF to 22nF capacitor from SS to SGND to set the
soft-start and fault timer periods. SS sources 2µA to an external soft-start
capacitor during start-up and when a fault is detected. As the voltage at SS
increases to 1.2V, the voltage at COMP is clamped to 0.7V above the voltage at
SS limiting the startup current. Under a fault condition, SS ramps at the same rate
15
16
8
9
SS
FB
as in soft-start. When the voltage at SS reaches 1.2V,
is asserted and the
FAULT
regulator is disabled. The external capacitor at SS is discharged to ground when
not in use or when under voltage lockout or thermal shutdown occurs.
Regulation Feedback Input. Connect to external resistive voltage divider from the
output voltage to FB to set output voltage.
MP1527 Rev 1.8_8/31/05
Monolithic Power Systems, Inc.
3
MP1527
2A, 1.3MHz
Step-Up Converter
Monolithic Power Systems
Typical Operating Characteristics (Circuit of Figure 9: Unless Otherwise Specified)
Figure 2: MP1527 responding to FAULT being
driven low
Figure 3: MP1527 responding to an overload
VOUT
VOUT
VSS
VSS
VFAULT
VFAULT
Figure 4: MP1527 starting from EN being
driven low-to-high
Figure 5: Transient Load Response. Load
driven from 50mA to 500mA
VOUT
VOUT
VSS
VEN
IIN (500mA/Div)
MP1527 Rev 1.8_8/31/05
Monolithic Power Systems, Inc.
4
MP1527
2A, 1.3MHz
Step-Up Converter
Monolithic Power Systems
Figure 6: Quiescent Current versus Input Voltage (Bootstrapped)
1000
900
800
700
600
500
400
300
200
100
0
0
5
10
15
20
25
Input Voltage (V)
Figure 7: Efficiency vs. Load Current (Bootstrapped)
100.00%
95.00%
90.00%
85.00%
80.00%
75.00%
70.00%
65.00%
60.00%
55.00%
50.00%
VOUT=12V
VIN=3.3V
VIN=5V
VIN=8V
10
100
1000
Load Current (mA)
MP1527 Rev 1.8_8/31/05
Monolithic Power Systems, Inc.
5
MP1527
2A, 1.3MHz
Step-Up Converter
Monolithic Power Systems
Figure 8: Efficiency vs. Load Current (Non-Bootstrapped)
100.00%
95.00%
90.00%
85.00%
80.00%
75.00%
70.00%
65.00%
60.00%
55.00%
50.00%
VOUT = 12V
VIN=3.3V
VIN=5V
VIN=8V
10
100
1000
Load Current (mA)
Figure 9: VIN = 5V, VOUT = 12V @ 500mA Load
Figure 10: Driving Multiple Strings of White LEDs
VIN=2.6
to 25V
V = 5V
IN
10µF
4.7µF
4.7µH
100K
1N5819HW
IN
1µF
1µF
100K
VOUT = 12V
@0.5A
FAULT
FAULT
EN
SW
C2
10µF
Up to
6 LEDs
MBR0530
ON/OFF
91K
IN
SW
FB
per String
SS
10nF
10nF
FAULT
FAULT
BP
FB
COMP
ON/OFF
EN MP1527
C4
10K
60
60
60
COMP
N/A
SS
BP
R3
SGND PGND
10K
5.6K
SGND
PGND
10nF
10nF
C3
5.6nF
4.7nF
MP1527 Rev 1.8_8/31/05
Monolithic Power Systems, Inc.
6
MP1527
2A, 1.3MHz
Step-Up Converter
Monolithic Power Systems
Figure 11: Functional Block Diagram
IN
2.4V
BP
EN
LDO
OSCILLATOR
VDD
SW
PWM
CONTROL
LOGIC
CURRENT
SENSE AMP
2µA
SS
PGND
1.098V
SOFT-
START
&
FAULT
FAULT
FB
1.22V
GM
CONTROL
COMP
SGND
MP1527 Rev 1.8_8/31/05
Monolithic Power Systems, Inc.
7
MP1527
2A, 1.3MHz
Step-Up Converter
Monolithic Power Systems
Functional Description
The MP1527 uses a 1.3MHz fixed-frequency,
current-mode regulation architecture to
regulate the output voltage. The MP1527
measures the output voltage through an
external resistive voltage divider and compares
that to the internal 1.22V reference to generate
the error voltage at COMP. The current-mode
regulator compares voltage at the COMP pin
to the inductor current to regulate the output
voltage. The use of current-mode regulation
improves transient response and control loop
stability.
voltage at startup due to input current
overshoot at startup. When power is applied to
the MP1527, or with power applied when
enable is asserted, a 2µA internal current
source charges the external capacitor at SS.
As the capacitor charges, the voltage at SS
rises. The MP1527 internally clamps the
voltage at COMP to 0.7V above the voltage at
SS. This limits the inductor current at start-up,
forcing the input current to rise slowly to the
current required to regulate the output voltage
during soft-start.
At the beginning of each cycle, the n-channel
MOSFET switch is turned on, forcing the
inductor current to rise. The current at the
source of the switch is internally measured and
converted to a voltage by the current sense
amplifier. That voltage is compared to the
error voltage at COMP. When the inductor
current rises sufficiently, the PWM comparator
turns off the switch forcing the inductor current
to the output capacitor through the external
rectifier. This forces the inductor current to
decrease. The peak inductor current is
controlled by the voltage at COMP, which in
turn is controlled by the output voltage. Thus
the output voltage controls the inductor current
to satisfy the load.
The soft-start period is determined by the
equation:
t
SS = 2.75 *105 * CSS
Where CSS (in F) is the soft-start capacitor from
SS to SGND, and tSS (in seconds) is the soft-
start period.
Determine the capacitor required for a given
soft-start period by the equation:
CSS = 3.64 *10-6 * tSS
Use values for CSS between 10nF and 22nF to
set the soft-start period.
Fault Timer-Latch Function
Internal Low-Dropout Regulator
The MP1527 includes an output fault detector
and timer-latch circuitry to disable the regulator
in the event of an undervoltage, overcurrent, or
The internal power to the MP1527 is supplied
from the input voltage (IN) through an internal
2.4V low-dropout linear regulator, whose
output is BP. Bypass BP to SGND with a 10nF
or greater capacitor to insure the MP1527
operates properly. The internal regulator can
not supply any more current than is required to
operate the MP1527, therefore do not apply
any external load to BP.
thermal overload.
Once the soft-start is
complete, the fault comparator monitors the
voltage at FB. If the voltage falls below the
1.098V fault threshold, the capacitor at SS
charges through an internal 2µA current
source. If the fault condition remains long
enough for the capacitor at SS to charge to
1.2V, the FAULT output is pulled low and the
power switch is turned off, disabling the output.
Soft-Start
The MP1527 includes a soft-start timer that
limits the voltage at COMP during start-up to
prevent excessive current at the input. This
prevents premature termination of the source
MP1527 Rev 1.8_8/31/05
Monolithic Power Systems, Inc.
8
MP1527
2A, 1.3MHz
Step-Up Converter
Monolithic Power Systems
The fault time-out period is determined by the
equation:
minimum. Ceramic capacitors are preferred,
but tantalum or low-ESR electrolytic capacitors
may also suffice.
tFAULT = 6*105 * CSS
Use an input capacitor value greater than
4.7µF. The capacitor can be electrolytic,
tantalum or ceramic. However since it absorbs
the input switching current it requires an
adequate ripple current rating. Use a capacitor
with RMS current rating greater than the
inductor ripple current (see Selecting The
Inductor to determine the inductor ripple
current).
To insure stable operation place the input
capacitor as close to the IC as possible.
Alternately a smaller high quality ceramic
0.1µF capacitor may be placed closer to the IC
with the larger capacitor placed further away. If
using this technique, it is recommended that
If multiple MP1527 regulators are used in the
same circuit, the FAULT input/outputs can be
connected together. Should any one regulator
indicate a fault, it pulls all FAULT input/outputs
low, disabling all regulators. This insures that
all outputs are disabled should any one output
detect a fault. Pull-up FAULT to the input
voltage (IN) through a 100KΩ resistor. The
leakage current at FAULT is less than 250nA,
so up to 20 FAULT input/outputs can be
connected together through a single 100KΩ
pull-up resistor. To reduce current draw when
FAULT is active, a higher value pull-up resistor
may be used. Calculate the pull-up resistor
value by the equation:
the larger capacitor be
a
tantalum or
electrolytic type. All ceramic capacitors should
be placed close to the MP1527.
100kΩ ≤ RPULL-UP ≤ 2MΩ / N
Where N is the number of FAULT input/outputs
connected together.
Selecting the Output Capacitor
The output capacitor is required to maintain
the DC output voltage. Low ESR capacitors
are preferred to keep the output voltage ripple
to a minimum. The characteristic of the output
capacitor also affects the stability of the
regulation control system. Ceramic, tantalum,
or low ESR electrolytic capacitors are
recommended. In the case of ceramic
capacitors, the impedance of the capacitor at
the switching frequency is dominated by the
capacitance, and so the output voltage ripple is
mostly independent of the ESR. The output
voltage ripple is estimated to be:
Setting the Output Voltage
Set the output voltage by selecting the
resistive voltage divider ratio. The voltage
divider drops the output voltage to the 1.22V
feedback threshold voltage. Use 10KΩ for the
low-side resistor of the voltage divider.
Determine the high side resistor by the
equation:
RH = (VOUT - VFB) / (VFB / RL)
where RH is the high-side resistor, RL is the
low-side resistor, VOUT is the output voltage
and VFB is the feedback regulation threshold.
⎛
⎜
⎜
⎝
⎞
⎟
⎟
⎠
VIN
1-
×ILOAD
VOUT
VRIPPLE
≈
For RL = 10KΩ and VFB = 1.22V, then
RH (KΩ) = 8.20* (VOUT – 1.22V)
C2× fSW
Where VRIPPLE is the output ripple voltage, VIN
and VOUT are the DC input and output voltages
respectively, ILOAD is the load current, fSW is the
switching frequency, and C2 is the capacitance
of the output capacitor.
Selecting the Input Capacitor
An input capacitor is required to supply the AC
ripple current to the inductor, while limiting
noise at the input source. A low ESR capacitor
is required to keep the noise at the IC to a
In the case of tantalum or low-ESR electrolytic
capacitors, the ESR dominates the impedance
MP1527 Rev 1.8_8/31/05
Monolithic Power Systems, Inc.
9
MP1527
2A, 1.3MHz
Step-Up Converter
Monolithic Power Systems
at the switching frequency, and so the output
Selecting the Diode
ripple is calculated as:
VIN
The output rectifier diode supplies current to the
inductor when the internal MOSFET is off. To
reduce losses due to diode forward voltage and
recovery time, use a Schottky diode with the
MP1527. The diode should be rated for a
reverse voltage equal to or greater than the
output voltage used. The average current
rating must be greater than the maximum load
current expected, and the peak current rating
must be greater than the peak inductor current.
(1−
)×ILOAD
VOUT
C2× fSW
ILOAD × RESR × VOUT
VRIPPLE
≈
+
VIN
Where RESR is the equivalent series resistance
of the output capacitors.
Choose an output capacitor to satisfy the
output ripple and load transient requirements
of the design. A 4.7µF-22µF ceramic capacitor
is suitable for most applications.
Compensation
The output of the transconductance error
amplifier (COMP) is used to compensate the
regulation control system. The system uses
two poles and one zero to stabilize the control
loop. The poles are fP1 set by the output
capacitor and load resistance and fP2 set by
the compensation capacitor C3. The zero fZ1
is set by the compensation capacitor C3 and
the compensation resistor R3. These are
determined by the equations:
Selecting the Inductor
The inductor is required to force the higher
output voltage while being driven by the input
voltage. A larger value inductor results in less
ripple current that results in lower peak
inductor current, reducing stress on the
internal n-channel.switch. However, the larger
value inductor has a larger physical size,
higher series resistance, and/or lower
saturation current.
A 4.7µH inductor is recommended for most
fP1 = 1 / (π*C2*RLOAD
)
applications. However,
a
more exact
inductance value can be calculated. A good
rule of thumb is to allow the peak-to-peak
ripple current to be approximately 30-50% of
the maximum input current. Make sure that the
peak inductor current is below 75% of the
current limit at the operating duty cycle to
prevent loss of regulation due to the current
limit. Also make sure that the inductor does not
saturate under the worst-case load transient
and startup conditions. Calculate the required
inductance value by the equation:
fP2 = GEA / (2π*AVEA*C3)
fZ1 = 1 / (2π*C3*R3)
Where RLOAD is the load resistance, GEA is the
error amplifier transconductance, and AVEA is
the error amplifier voltage gain.
The DC loop gain is:
AVDC = AVEA*GCS*(VIN / VOUT)*RLOAD*(VFB / VOUT
)
VIN × (VOUT - VIN )
L =
VOUT × fSW × ∆I
or
VOUT ×ILOAD
(MAX)
2
IIN(MAX)
∆I =
=
A
VDC = AVEA*GCS*VIN*VFB*RLOAD /(VOUT)
V ×η
IN
(
30% − 50% IIN(MAX)
)
Where GCS is the current sense gain, VIN is the
input voltage, VFB is the feedback regulation
threshold, and VOUT is the regulated output
voltage.
Where ILOAD(MAX) is the maximum load current, ∆I
is the peak-to-peak inductor ripple current, and η
is efficiency.
MP1527 Rev 1.8_8/31/05
Monolithic Power Systems, Inc.
10
MP1527
2A, 1.3MHz
Step-Up Converter
Monolithic Power Systems
There is also a right-half-plane zero (fRHPZ) that
exists in all continuous mode (continuous
mode means that the inductor current does not
drop to zero on each cycle) step-up
converters. The frequency of the right half
plane zero is:
R3 = VIN*RLOAD-MIN*C2 / (10GCS*GEA*VFB*L)
The minimum load resistance (RLOAD-MIN) is
equal to the regulated output voltage (VOUT
divided by the maximum load current ILOAD-MAX
)
.
Substituting that into the above equation:
2
2
f
RHPZ = VIN *RLOAD / (2π*L*VOUT
)
R3 = VIN*VOUT*C2 /(10GCS*GEA *VFB*L*ILOAD-MAX
)
where L is the value of the inductor.
Putting in the known constant values:
To stabilize the regulation control loop, the
crossover frequency (The frequency where the
loop gain drop to 0dB or gain of 1, indicated as
fC) should be at least one decade below the
right-half-plane zero and should be at most
75KHz. fRHPZ is at its lowest frequency at
maximum output load current (RLOAD is at a
minimum)
(1) R3 ≈ 48*VIN*VOUT*C2 / (L*ILOAD-MAX
For fC = 75KHz,
fC = (GCS*GEA*VIN*VFB*R3) / (2π*C2*VOUT
)
2
)
Solving for R3,
R3 = (2π*fC*C2*VOUT2 / (GCS*GEA*VIN*VFB)
The crossover frequency is calculated by the
equation:
Using 75KHz for fC and putting in the other
known constants:
fC = AVDC*fP1*fP2 / fZ1
(2) R3 ≈ 2.2x108*C2*VOUT2 / VIN
or
2
The value of the compensation resistor is
limited to 10Kꢀ to prevent overshoot on the
output at turn-on. So if the value calculated for
R3 from either equation (1) or equation (2) is
greater than 10kꢀ, use 10Kꢀ for R3.
fC = GCS*GEA*VIN*VFB*R3 / (2π*C2*VOUT
)
The known values are:
G
G
V
CS = 4.3S
EA = 400µS
FB = 1.22V
Choose C3 to set the zero frequency fZ1 to
one-fourth of the crossover frequency fC:
Putting in the known constants:
fC = 3.3x10-4 *VIN *R3/ (C2*VOUT
fZ1 = fC / 4
or
2
)
If the frequency of the right-half-pane zero
fRHPZ is less than 750KHz, then the crossover
frequency should be 1/10 of fRHPZ, and
determine the compensation resistor (R3) with
equation (1). If fRHPZ is greater than or equal to
750KHz, set the crossover frequency to 75KHz
with equation (2).
2
1 /(2π*C3*R3) = GCS*GEA*VIN*VFB*R3 / (8π*C2*VOUT
Solving for C3:
)
C3 = 4*C2*VOUT2 / (GCS*GEA*VIN*VFB*R32)
Entering the known values gives:
For fC = fRHPZ / 10, then
MP1527 Rev 1.8_8/31/05
Monolithic Power Systems, Inc.
11
MP1527
2A, 1.3MHz
Step-Up Converter
Monolithic Power Systems
C3 ≈ 1.9x103 C2 VOUT2 / (VIN R32)
Example
In some cases, if an output capacitor with high
capacitance and high equivalent series
resistance (ESR) is used, then a second
compensation capacitor (from COMP to
SGND) is required to compensate for the zero
introduced by the output capacitor ESR. The
extra capacitor is required if the ESR zero is
less than 4x the crossover frequency. The
ESR zero frequency is:
Given:
Input Voltage (VIN): 5V
Output Voltage (VOUT): 12V
Maximum Load Current (ILOAD-MAX): 500mA
Output Capacitor (C2): 10µF (ESR=10mꢀ
Maximum)
Inductor Value (L): 4.7µH
Find the frequency of the right-half-plane zero:
f
ZESR = 1 / (2π*C2*RESR
)
f
RHPZ = VIN2 / (2π*L*VOUT*ILOAD-MAX
fRHPZ = (5V)2 /
)
The second compensation capacitor is
required if:
(2π*4.7µH*12V*500mA)=141KHz
4*fC ≥ fZESR
The frequency of the right-half-plane zero is
less than 750khz, so use equation (1) to
determine the compensation resistor R3:
or
2
4*GCS*GEA*VIN*VFB*R3
(2π*C2*RESR
/
(2π*C2*VOUT
)
≥
1
/
R3 ≈ 48*VIN*VOUT*C2 / (L*ILOAD-MAX
R3 ≈ 48*5*12*10µF/(4.7µH*500mA) =12.3Kꢀ
(use 10Kꢀ)
)
)
Simplifying:
(8.4x10-3*VIN*R3*RESR )/ VOUT2 ≥ 1
Find the compensation capacitor C3:
C3 ≈ 1.9x103*C2*VOUT2 / (VIN*R32)
If this is the case, calculate the second
compensation capacitor by the equation:
C3 ≈ 1.9x103*10µF (12V)2 / (5 * 10Kꢀ2) = 5.4nF
R3*C4 = C2*RESR
or
(use the nearest standard value, 5.6nF)
Determine if the second compensation
capacitor is required:
C4 = (C2*RESR) / R3
8.4x10-3 * 5V * 5.6Kꢀ * 10mꢀ / 12V2 = 0.016 ≤ 1
Therefore no second compensation capacitor
is required.
MP1527 Rev 1.8_8/31/05
Monolithic Power Systems, Inc.
12
MP1527
2A, 1.3MHz
Step-Up Converter
Monolithic Power Systems
Packaging
QFN16 (4x4)
3.950 (0.156)
4.050 (0.159)
Pin 1 Identification
2.35 (0.093)
2.45 (0.097)
Pin 1 Dot
By marking
16
0.550 (0.217)
0.650 (0.256)
0.40 (0.0158)
0.50 (0.0197)
1
4
QFN 16L
(4 X 4mm)
0.650
BSC
3.950 (0.156)
4.050 (0.159)
R0.030Max.
0.28 (0.011)
0.38 (0.015)
9
8
5
2.280 (0.898)
Ref.
Top View
Btm View
0.850 ( 0.0335)
0.950 (0.0374)
0.178 (0.007)
0.228 (0.009)
0.000-0.025
MP1527 Rev 1.8_8/31/05
Monolithic Power Systems, Inc.
13
MP1527
2A, 1.3MHz
Step-Up Converter
Monolithic Power Systems
TSSOP14
NOTICE: MPS believes the information in this document to be accurate and reliable. However, it is subject to change
without notice. Please contact the factory for current specifications. No responsibility is assumed by MPS for its use or fit to
any application, nor for infringement of patent or other rights of third parties.
MP1527 Rev 1.8
8/31/05
Monolithic Power Systems, Inc.
983 University Ave, Building A, Los Gatos, CA 95032 USA
14
© 2003 MPS, Inc.
Tel: 408-357-6600 ♦ Fax: 408-357-6601 ♦ Web: www.monolithicpower.com
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