Anpec APW8722BKAI-TRG 5v to 12v single buck voltage mode pwm controller Datasheet

APW8722/A/B/C/D
5V to 12V Single Buck Voltage Mode PWM Controller
Features
General Description
•
Wide 5V to 12V Supply Voltage
The APW8722 is a voltage mode, fixed 200kHz/300kHz/
•
Power-On-Reset Monitoring on VCC
•
Excellent Output Voltage Regulations
600kHz switching frequency, synchronous buck converter.
The APW8722 allows wide input voltage that is either a
single 5~12V or two supply voltage(s) for various
applications. A power-on-reset (POR) circuit monitors the
- 0.6V Internal Reference for APW8722/A/D
- 0.8V Internal Reference for APW8722B/C
- ±0.6% Over-Temperature Range
•
Integrated Soft-Start
•
Voltage Mode PWM Operation with External
VCC supply voltage to prevent wrong logic controls. A builtin soft-start circuit prevents the output voltages from overshoot as well as limits the input current. An internal 0.6V
temperature-compensated reference voltage with high
Compensation
•
Up to 90% Duty Ratio for Fast Transient Response
•
Constant Switching Frequency
accuracy is designed to meet the requirement of low output voltage applications. The APW8722 provides excellent output voltage regulations against load current
variation.
The controller’s over-current protection monitors the out-
- 300kHz ±10% for APW8722/B
- 200kHz ±10% for APW8722C
- 600kHz ±10% for APW8722A/D
•
Integrated Bootstrap Forward P-CH MOSFET
•
50% Under-Voltage Protection
•
125% Over-Voltage Protection
•
Adjustable Over-Current Protection Threshold
put current by using the voltage drop across the RDS
(ON) of low-side MOSFET, eliminating the need for a current sensing resistor that features high efficiency and
low cost. In addition, the APW8722 also integrates excellent protection functions. The over-voltage protection (OVP)
, under-voltage protection (UVP). OVP circuit which moni-
- Using the RDS(ON) of Low-Side MOSFET
•
Shutdown Control by COMP
•
SOP-8P Package
•
Lead Free and Green Devices Available
tors the FB voltage to prevent the PWM output from over
voltage, and UVP circuit which monitors the FB voltage to
prevent the PWM output from under voltage or short circuit.
The APW8722 is available in SOP-8P packages
(RoHS Compliant)
Applications
•
•
DSL, Switch HUB
•
Wireless Lan
•
Notebook Computer
Graphic Cards
•
Mother Board
•
LCD Monitor/TV
ANPEC reserves the right to make changes to improve reliability or manufacturability without notice, and
advise customers to obtain the latest version of relevant information to verify before placing orders.
Copyright  ANPEC Electronics Corp.
Rev. A.3 - Jun., 2013
1
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APW8722/A/B/C/D
Simplified Application Circuit
VVCC
VIN
5
7
OFF
BOOT
VCC
COMP
UGATE
APW8722
ON
PHASE
LGATE
6
1
2
VOUT
8
4
FB
GND
3
Ordering and Marking Information
APW8722/A/B/C/D
Assembly Material
Handling Code
Temperature Range
Package Code
APW8722/A/B/C/D
APW8722X
XXXXX
KA :
X – A/B/C/D
Package Code
KA : SOP-8P
Operating Ambient Temperature Range
I : -40 to 85 oC
Handling Code
TR : Tape & Reel
Assembly Material
G : Halogen and Lead Free Device
XXXXX - Date Code
Note: ANPEC lead-free products contain molding compounds/die attach materials and 100% matte tin plate termination finish; which
are fully compliant with RoHS. ANPEC lead-free products meet or exceed the lead-free requirements of IPC/JEDEC J-STD-020D for
MSL classification at lead-free peak reflow temperature. ANPEC defines “Green” to mean lead-free (RoHS compliant) and halogen
free (Br or Cl does not exceed 900ppm by weight in homogeneous material and total of Br and Cl does not exceed 1500ppm by
weight).
Pin Configuration
APW8722A
APW8722/B/C/D
BOOT 1
UGATE 2
GND 3
LGATE/OCSET 4
9 GND
8
7
6
5
BOOT 1
UGATE 2
OCSET 3
LGATE 4
PHASE
COMP
FB
VCC
PHASE
COMP
FB
VCC
SOP-8P
(top view)
SOP-8P
(top view)
Copyright  ANPEC Electronics Corp.
Rev. A.3 - Jun., 2013
9 GND
8
7
6
5
2
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APW8722/A/B/C/D
Absolute Maximum Ratings (Note 1)
Symbol
VVCC
VBOOT
Rating
Unit
VCC Supply Voltage (VCC to GND)
Parameter
-0.3 ~ 16
V
BOOT Supply Voltage (BOOT to PHASE)
-0.3 ~ 16
V
BOOT Supply Voltage (BOOT to GND)
-0.3 ~ 32
V
VUGATE
UGATE Voltage (UGATE to PHASE)
VLGATE
LGATE Voltage (LGATE to GND)
VPHASE
PHASE Voltage (PHASE to GND)
> 20ns
-0.3 ~ VBOOT+0.3
V
< 20ns
-5 ~ VBOOT+5
V
> 20ns
-0.3 ~ VVCC+0.3
V
< 20ns
-5 ~ VVCC+5
V
> 20ns
-0.3 ~ 16
V
< 20ns
-5 ~ 25
V
FB ,COMP to GND
POK to GND
TJ
Maximum Junction Temperature
TSTG
Storage Temperature
TSDR
Maximum Lead Soldering Temperature, 10 Seconds
-0.3 ~ 7
V
-0.3~VCC+0.3
V
150
°C
-65 ~ 150
°C
260
°C
Note1: 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 under "recommended operating conditions" is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device
reliability.
Thermal Characteristics
Symbol
θJA
Parameter
Thermal Resistance -Junction to Ambient
Typical Value
Unit
(Note 2)
SOP-8P
°C/W
60
Note 2: θJA is measured with the component mounted on a high effective thermal conductivity test board in free air.
Recommended Operating Conditions (Note 3)
Symbol
Range
Unit
4.5 ~ 13.2
V
Converter Output Voltage for APW8722/A/D
0.6 ~ 5
V
Converter Output Voltage for APW8722B/C
0.8 ~ 5
V
VIN
Converter Input Voltage
3~13.2
V
IOUT
Converter Output Current
0 ~ 25
A
TA
Ambient Temperature
-40 ~ 85
°C
TJ
Junction Temperature
-40 ~ 125
°C
VVCC
VOUT
Parameter
VCC Supply Voltage (VCC to GND)
Note 3: Refer to the application circuit for further information.
Copyright  ANPEC Electronics Corp.
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APW8722/A/B/C/D
Electrical Characteristics
Refer to the typical application circuit. These specifications apply over VVCC = 12V, TA = -40°C to 85°C, unless otherwise
noted. Typical values are at TA = 25°C.
Symbol
Parameter
APW8722
Test Conditions
Unit
Min.
Typ.
Max.
INPUT SUPPLY VOLTAGE AND CURRENT
IVCC
VCC Supply Current (Shutdown Mode)
UGATE and LGATE open;
COMP=GND
-
-
550
µA
VCC Supply Current
UGATE and LGATE open
-
2.5
10
mA
Rising VCC POR Threshold
3.8
4.1
4.4
V
VCC POR Hysteresis
0.3
0.5
0.6
V
For APW8722/B
270
300
330
For APW8722C
180
200
220
For APW8722A/D
540
600
660
(1.2V~2.7V typical)
-
1.5
-
V
-
-
90
%
POWER-ON-RESET(POR)
OSCILLATOR
FOSC
Oscillator Frequency
∆VOSC
Oscillator Sawtooth Amplitude
DMAX
Maximum Duty Cycle
(Note 4)
kHz
REFERENCE
VREF
APW8722/A/D Reference Voltage
TA = -40 ~ 85°C
0.596
0.6
0.604
APW8722B/C Reference Voltage
TA = -40 ~ 85°C
0.795
0.8
0.805
V
ERROR AMPLIFIER
Open-Loop GAIN (Note 4)
RL = 10kΩ, CL = 10pF
-
90
-
dB
Open-Loop Bandwidth (Note 4)
RL = 10kΩ, CL = 10pF
-
20
-
MHz
FB Input Leakage Current
VFB = 0.6V
-
-
0.1
µA
High-side Gate Driver Source Current
VBOOT= 12V, VUGATE-PHASE = 6V
-
1.0
-
High-side Gate Driver Sink Current
VBOOT= 12V, VUGATE-PHASE = 6V
-
1.1
-
Low-side Gate Driver Source Current
VVCC = 12V, VLGATE-GND = 6V
-
1.8
-
Low-side Gate Driver Sink Current
VVCC = 12V, VLGATE-GND = 6V
-
2.0
-
-
30
-
GATE DRIVERS
TD
Dead-time (Note 4)
A
ns
PROTECTIONS
VFB_UV
VFB_OV
45
50
55
%
Under-Voltage Debounce Interval
FB Under-Voltage Protection Trip Point
Percentage of VREF
-
2
-
µs
Under-Voltage Protection Enable
Delay
-
1.5
-
ms
FB Over-Voltage Protection Rising
Threshold
VFB rising
120
125
130
%
FB Over-Voltage Protection Falling
Threshold
VFB falling
100
105
110
%
-
2
-
µs
Built-in Maximum OCP Voltage
-
1200
-
mV
OCSET Current Source
9
10
11
µA
Over-Voltage Debounce Interval
VOCP_MAX
IOCSET
Copyright  ANPEC Electronics Corp.
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APW8722/A/B/C/D
Electrical Characteristics (Cont.)
Refer to the typical application circuit. These specifications apply over VVCC = 12V, TA = -40°C to 85°C, unless otherwise
noted. Typical values are at TA = 25°C.
Symbol
Parameter
APW8722
Test Conditions
Min.
Unit
Typ.
Max.
SOFT-START
VDISABLE
TSS
Shutdown Threshold of VCOMP
-
-
0.4
V
Internal Soft-Start Interval (Note 4)
-
1.5
-
ms
Note 4: Guaranteed by design, not production tested.
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APW8722/A/B/C/D
Typical Operating Characteristics
Efficiency vs. Load Current
FSW=300KHz, VOUT=1.2V
Reference Voltage vs. Junction
Temperature
0.61
90
0.605
Efficiency (%)
Reference Voltage (V)
VCC = 12V
0.6
85
80
75
70
0.595
VIN=12V
H-Side: APW3109x1
L-Side: APW3116x1
65
0.59
-20
0
20
40
60
80
100
60
0.1
120
1
Junction Temperature (oC)
20.0
Switching Frequency vs. Junction
Temperature
350
650
340
640
330
Switching Frequency (kHz)
Switching Frequency (kHz)
Switching Frequency vs. Junction
Temperature
320
310
300
290
280
270
260
630
620
610
600
590
580
570
560
250
550
-20
0
20
40
60
80
100
120
-20
0
o
20
40
60
80
100
120
Junction Temperature (oC)
Junction Temperature ( C)
IOCSET vs. Junction Temperature
Load Regulation
0.3
11.4
0.2
11
OCSET Current Source (uA)
Output Voltage Variation (%)
10.0
Output Current (A)
0.1
0
-0.1
-0.2
-0.3
10.6
10.2
9.8
9.2
8.8
8.2
0
2
4
6
8
10
-20
Output Current (A)
Copyright  ANPEC Electronics Corp.
Rev. A.3 - Jun., 2013
0
20
40
60
80
100
120
Junction Temperature (oC)
6
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APW8722/A/B/C/D
Operating Waveforms
Refer to the typical application circuit. The test condition is VIN=12V, TA= 25oC unless otherwise specified.
Power On
Power Off
VIN
VIN
1
1
VOUT
VOUT
2
2
VUGATE
VUGATE
3
3
CH1: VIN, 5V/Div
CH2: VOUT, 500mV/Div
CH3: VUGATE, 10V/Div
TIME: 1ms/Div
CH1: VIN, 5V/Div
CH2: VOUT, 500mV/Div
CH3: VUGATE, 10V/Div
TIME: 50ms/Div
Enable
Shutdown
RLOAD =12Ω
VCOMP
1
1
VCOMP
VOUT
VOUT
2
2
VPHASE
VPHASE
3
3
CH1: VEN, 5V/Div, DC
CH2: VOUT, 500mV/Div, DC
CH3: VPHASE, 10V/Div, DC
TIME: 1ms/Div
Copyright  ANPEC Electronics Corp.
Rev. A.3 - Jun., 2013
CH1: VCOMP, 1V/Div
CH2: VOUT, 500mV/Div
CH3: VPHASE, 10V/Div
TIME: 10ms/Div
7
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APW8722/A/B/C/D
Operating Waveforms
Refer to the typical application circuit. The test condition is VIN=12V, TA= 25oC unless otherwise specified.
Over-Current Protection
Under-Voltage Protection
R OCSET =open ,R DS (low Side )=12.5mΩ
VOUT
UVP
UVP
VFB
UVP
1
1
VPHASE
OCP
2
IL
IL
3
2
CH1: VOUT, 500mV/Div
CH2: IL,10A/Div
TIME: 20ms/Div
CH1: VFB, 200mV/Div
CH2: VPHASE,10V/Div
CH3: IL,10A/Div
TIME: 10us/Div
UGATE Falling
UGATE Rising
V UGATE
1
VUGATE
1
V LGATE
2
3
V PHASE
23
3
VLGATE
3
CH1: VUGATE, 20V/Div
CH2: VLGATE, 10V/Div
CH3: VPHASE, 10V/Div
TIME: 20ns/Div
Copyright  ANPEC Electronics Corp.
Rev. A.3 - Jun., 2013
V PHASE
CH1: VUGATE, 20V/Div
CH2: VLGATE, 10V/Div
CH3: VPHASE, 10V/Div
TIME: 20ns/Div
8
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APW8722/A/B/C/D
Operating Waveforms
Refer to the typical application circuit. The test condition is VIN=12V, TA= 25oC unless otherwise specified.
Load Transient
VOUT
1
I OUT
32
CH1: VOUT, 50mV/Div,AC
CH2: IOUT, 5A/Div
TIME: 200us/Div
Copyright  ANPEC Electronics Corp.
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APW8722/A/B/C/D
Pin Description
PIN
No.
APW8722A
Function Description
Name
APW8722/B/C/D
1
1
BOOT
This pin provides the bootstrap voltage to the high-side gate driver for
driving the N-channel MOSFET. An external capacitor from PHASE to
BOOT, an internal switch generates the bootstrap voltage for the
high-side gate driver (UGATE).
2
2
UGATE
High-side Gate Driver Output. This pin is the gate driver for high-side
MOSFET.
-
3
GND
Signal and Power ground. Connecting this pin to system ground.
3
-
OCSET
Current-Limit Threshold Setting Pin. There is an internal source current
10uA through a resistor from OCSET pin to GND. This pin is used to
monitor the voltage drop across the Drain and Source of the low-side
MOSFET for current-limit
4
-
LGATE
Output of The Low-side MOSFET Driver. Connect this pin to the low-side
MOSFET.
-
4
LGATE/
OCSET
Low-side Gate Driver Output and Over-Current Setting Input. This pin is
the gate driver for low-side MOSFET. It also used to set the maximum
inductor current. Refer to the section in “Function Description” for detail.
5
5
VCC
Power Supply Input. Connect a nominal 5V to 12V power supply voltage
to this pin. A power-on reset function monitors the input voltage at this
pin. It is recommended that a decoupling capacitor (1 to 10µF) be
connected to GND for noise decoupling.
6
6
FB
Feedback Input of Converter. The converter senses feedback voltage via
FB and regulates the FB voltage at 0.6V/0.8V. Connecting FB with a
resistor-divider from the output sets the output voltage of the converter.
This is a multiplexed pin. During soft-start and normal converter
operation, this pin represents the output of the error amplifier. It is used to
compensate the regulation control loop in combination with the FB pin.
7
7
COMP
Pulling COMP low (VDISABLE = 0.4V max.) will shut down the controller.
When the pull-down device is released, the COMP pin will start to rise.
When the COMP pin rises above the VDISABLE trip point, the APW8722 will
begin a new initialization and soft-start cycle.
8
8
PHASE
This pin is the return path for the high-side gate driver. Connecting this
pin to the high-side MOSFET source and connect a capacitor to BOOT
for the bootstrap voltage. This pin is also used to monitor the voltage drop
across the low-side MOSFET for over-current protection.
9
(Exposed Pad)
9
(Exposed Pad)
GND
Thermal Pad. Connect this pad to the system ground plan for
good thermal conductivity.
Copyright  ANPEC Electronics Corp.
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APW8722/A/B/C/D
Block Diagram
VCC
Regulator
IOCSET
(10 µA typical)
Sample
and Hold
Power-On
Reset
BOOT
Sense Low
Side
V REF
UGATE
VROCSET
(0 .6V /0.8V typical)
To
LGATE
PHASE
UVP
Comparator
0.5
VROCSET
Soft Start
and
Fault Logic
IZCMP
VCC
1.25
Inhibit
OVP
Comparator
Gate
Control
LGATE
Soft-start
PWM
Comparator
Error Amplifier
VREF
Oscillator
0 .4V
FB
Disable
GND
COMP
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APW8722/A/B/C/D
Typical Application Circuit
For APW8722/B/C/D
VCC Supply
(5~12V)
C4
1µF
R4
2R2
5
Q3
2N7002
C1
100pF
BOOT
VCC
7
OFF
ON
VIN
COMP
UGATE
APW8722
C2
100nF
PHASE
1
C3
0.1µF
C IN1
C IN2
1µF
220µF x 2
Q1
APM 2510
L1
2
8
VOUT
0.5µH
R2
4.7kΩ
LGATE/ 4
OCSET
6
FB
Q2
APM 2556
R OCSET
GND
3
C OUT
1000 µF x 2
R1
1kΩ
R2
1kΩ
R3
1kΩ
C3
22 nF
For APW8722A
VCC Supply
(5~12V)
C4
1 µF
R4
2R2
Q3
2N7002
APW8722(SOP-8OP)
5
7
OFF
ON
C1
100pF
VIN
VCC
COMP
C2
100nF
BOOT
UGATE
PHASE
R2
4.7kΩ
1
2
FB
C IN1
C IN2
1µF
220µF x 2
Q1
APM 251
0
L1
8
LGATE 4
6
C3
0.1µF
0.5µH
Q2
APM 255
6
VOUT
C OUT
1000µF x 2
OCSET
3
R OCSET
R1
1kΩ
R3
1kΩ
C3
22nF
Copyright  ANPEC Electronics Corp.
Rev. A.3 - Jun., 2013
R3
1kΩ
12
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APW8722/A/B/C/D
Function Description
Power-On-Reset (POR)
A resistor (ROCSET), connected from the LGATE/OCSET to
The Power-On-Reset (POR) function of APW8722 con-
GND, programs the over-current trip level. Before the IC
initiates a soft-start process, an internal current source,
tinually monitors the input supply voltage (VCC) and ensures that the IC has sufficient supply voltage and can
IOCSET (10µA typical), flowing through the ROCSET develops
a voltage (VROCSET) across the ROCSET. The device holds
work well. The POR function initiates a soft-start process
while the VCC voltage just exceeds the POR threshold;
VROCSET and stops the current source IOCSET during normal
operation. When the voltage across the low-side MOSFET
the POR function also inhibits the operations of the IC
while the VCC voltage falls below the POR threshold.
exceeds the VROCSET, the APW8722 turns off the high-side
and low-side MOSFET,and the device will enters hiccup
Soft-Start
mode until the over-current phenomenon is released.
The APW8722 builds in a soft-start function about 1.5ms
(Typ.) interval, which controls the output voltage rising as
For avoid large inductor current occurring in short circuit
before power on, the controller reduces internal current
source, Iocset, to half during soft start time. It means that
well as limiting the current surge at the start-up. During
soft-start, an internal ramp voltage connected to the one
when APW8722 is in soft start interval, the internal current source, Iocset, is only 5µA (typical).
of the positive inputs of the error amplifier replaces the
reference voltage (0.6V typical) until the ramp voltage
The APW8722 has an internal OCP voltage, VOCP_MAX, and
the value is 1.2V (typical). When the ROCSET x IOCSET exceed
reaches the reference voltage. The soft-start circuit interval is shown as figure 1.
1.2V or the ROCSET is floating or not connected, the VROCSET
will be the default value 1.2V. The over current threshold
would be 1.2V across low-side MOSFET. The threshold
of the valley inductor current-limit is therefore given by:
Voltage(V)
POK Delay Time
VVCC
OCSET count completed
OCSET count start
(OCSET duratiom, t2-t1, less than 0.9ms)
ILIMIT =
VPOK
0.9xVREF
t0
t1 t2
VOUT
t3
t4
2 × IOCSET × ROCSET
RDS(ON) (low − side)
For the over-current is never occurred in the normal operating load range, the variation of all parameters in the
above equation should be considered:
- The RDS(ON) of low-side MOSFET is varied by tempera-
Time
ture and gate to source voltage. Users should determine the maximum RDS(ON) by using the manufacturer’s
Figure 1. Soft-Start Interval
datasheet.
- The minimum IOCSET (9µA) and minimum ROCSET should
Over-Current Protection of the PWM Converter
be used in the above equation.
- Note that the ILIMIT is the current flow through the low-
The over-current function protects the switching converter
against over-current or short-circuit conditions. The controller senses the inductor current by detecting the drain-
side MOSFET; ILIMIT must be greater than valley inductor
current which is output current minus the half of induc-
to-source voltage which is the product of the inductor’s
current and the on-resistance of the low-side MOSFET
tor ripple current.
during it’s on-state. This method enhances the converter’s
efficiency and reduces cost by eliminating a current sens-
ILIMIT > IOUT(MAX ) −
ing resistor required.
∆I
2
Where ∆I = output inductor ripple current
- The overshoot and transient peak current also should
be considered.
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APW8722/A/B/C/D
Function Description (Cont.)
Adaptive Shoot-Through Protection of the PWM Con-
Under-Voltage Protection
The under-voltage function monitors the voltage on FB
(VFB) by Under-Voltage (UV) comparator to protect the PWM
verter
The gate drivers incorporate an adaptive shoot-through
protection to prevent high-side and low-side MOSFETs
converter against short-circuit conditions. When the VFB
falls below the falling UVP threshold (50% VREF), a fault
from conducting simultaneously and shorting the input
supply. This is accomplished by ensuring the falling gate
signal is internally generated and the device turns off highside and low-side MOSFETs. The device will enters hic-
has turned off one MOSFET before the other is allowed to
rise.
cup mode until the under-voltage phenomenon is
released.
During turn-off the low-side MOSFET, the LGATE voltage
is monitored until it is below 1.5V threshold, at which
Over-Voltage Protection (OVP) of the PWM Converter
time the UGATE is released to rise after a constant delay.
During turn-off of the high-side MOSFET, the UGATE-toPHASE voltage is also monitored until it is below 1.5V
threshold, at which time the LGATE is released to rise
The over-voltage protection monitors the FB voltage to
prevent the output from over-voltage condition. When the
after a constant delay.
output voltage rises above 125% of the nominal output
voltage, the APW8722 turns off the high-side MOSFET
and turns on the low-side MOSFET until the output voltage falls below the falling below 105%, the OVP comparator is disengaged and both high-side and low-side
drivers turn off.
This OVP scheme only clamps the voltage overshoot and
does not invert the output voltage when otherwise activated with a continuously high output from low-side
MOSFET driver. It’s a common problem for OVP schemes
with a latch. Once an over-voltage fault condition is set, it
can be reset by releasing COMP or toggling VCC poweron-reset signal.
Shutdown and Enable
The APW8722 can be shut down or enabled by pulling
low the voltage on COMP. The COMP is a dual-function
pin. During normal operation, this pin represents the output of the error amplifier. It is used to compensate the
regulation control loop in combination with the FB pin.
Pulling the COMP low (VDISABLE = 0.4V maximum) places
the controller into shutdown mode which UGATE and
LGATE are pulled to PHASE and GND respectively.
When the pull-down device is released, the COMP voltage will start to rise. When the COMP voltage rises above
the VDISABLE threshold, the APW8722 will begin a new initialization and soft-start process.
Copyright  ANPEC Electronics Corp.
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Application Information
Output Voltage Selection
lower output ripple voltage. The ripple current and ripple
The output voltage can be programmed with a resistive
voltage can be approximated by:
IRIPPLE =
divider. Use 1% or better resistors for the resistive divider
is recommended. The FB pin is the inverter input of the
VIN − VOUT VOUT
×
FSW × L
VIN
where Fs is the switching frequency of the regulator.
error amplifier, and the reference voltage is 0.6V. The
output voltage is determined by:
∆VOUT = IRIPPLE x ESR

R 
VOUT = 0.6 × 1 + 1 
R
2

A tradeoff exists between the inductor’s ripple current and
the regulator load transient response time. A smaller in-
R2 is the resistor connected from FB to the GND.
ductor will give the regulator a faster load transient response at the expense of higher ripple current and vice
Output Capacitor Selection
versa. The maximum ripple current occurs at the maximum input voltage. A good starting point is to choose the
Where R1 is the resistor connected from VOUT to FB and
ripple current to be approximately 30% of the maximum
output current.
The selection of COUT is determined by the required effective series resistance (ESR) and voltage rating rather than
the actual capacitance requirement. Therefore, selecting
Once the inductance value has been chosen, selecting
an inductor is capable of carrying the required peak cur-
high performance low ESR capacitors is intended for
switching regulator applications. In some applications,
rent without going into saturation. In some types of
inductors, especially core that is make of ferrite, the ripple
multiple capacitors have to be paralleled to achieve the
desired ESR value. If tantalum capacitors are used, make
current will increase abruptly when it saturates. This will
result in a larger output ripple voltage.
sure they are surge tested by the manufactures. If in doubt,
consult the capacitors manufacturer.
PWM Compensation
Input Capacitor Selection
The output LC filter of a step down converter introduces a
The input capacitor is chosen based on the voltage rat-
double pole, which contributes with -40dB/decade gain
slope and 180 degrees phase shift in the control loop. A
ing and the RMS current rating. For reliable operation,
select the capacitor voltage rating to be at least 1.3 times
compensation network among COMP, FB, and V OUT
should be added. The compensation network is shown in
higher than the maximum input voltage. The maximum
RMS current rating requirement is approximately IOUT/2
Figure 5. The output LC filter consists of the output inductor and output capacitors. The transfer function of the LC
where IOUT is the load current. During power up, the input
capacitors have to handle large amount of surge current.
filter is given by:
If tantalum capacitors are used, make sure they are surge
tested by the manufactures. If in doubt, consult the ca-
FESR =
pacitors manufacturer.
For high frequency decoupling, a ceramic capacitor be-
1
2 × π × ESR × COUT
The FLC is the double poles of the LC filter, and FESR is the
zero introduced by the ESR of the output capacitor.
tween 0.1µF to 1µF can connect between VCC and ground
pin.
V PHASE
L
V OUT
Inductor Selection
The inductance of the inductor is determined by the out-
C OUT
put voltage requirement. The larger the inductance, the
lower the inductor’s current ripple. This will translate into
ESR
Figure 2. The Output LC Filter
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APW8722/A/B/C/D
Application Information(Cont.)
The poles and zeros of the transfer function are:
1
FZ1 =
2 × π × R2 × C2
1
FZ2 =
2 × π × (R1 + R3) × C3
1
FP1 =
 C1× C2 
2 × π × R2 × 

 C1 + C2 
FLC
GAIN (dB)
-40dB/dec
FESR
FP2 =
-20dB/dec
1
2 × π × R3 × C3
C1
R3
C3
R2
C2
V OUT
Frequency(Hz)
R1
Figure 3. The LC Filter GAIN and Frequency
FB
V COMP
V REF
The PWM modulator is shown in Figure 4. The input is
Figure 5. Compensation Network
the output of the error amplifier and the output is the
PHASE node. The transfer function of the PWM modulator
The closed loop gain of the converter can be written as:
is given by:
GAINPWM =
GAINLC X GAINPWM X GAINAMP
VIN
∆VOSC
Figure 6. shows the asymptotic plot of the closed loop
V IN
OSC
ΔV OSC
converter gain, and the following guidelines will help to
design the compensation network. Using the below
Driver
guidelines should give a compensation similar to the
curve plotted. A stable closed loop has a -20dB/ decade
PWM
Comparator
slope and a phase margin greater than 45 degree.
PHASE
Output of
Error Amplifier
1. Choose a value for R1, usually between 1K and 5K.
2. Select the desired zero crossover frequency
Driver
FO: (1/5 ~ 1/10) X FS >FO>FESR
Figure 4. The PWM Modulator
Use the following equation to calculate R2:
∆VOSC FO
R2 =
×
× R1
VIN
FLC
The compensation network is shown in Figure 5. It
provides a close loop transfer function with the highest
zero crossover frequency and sufficient phase margin.
The transfer function of error amplifier is given by:
GAINAMP
3. Place the first zero FZ1 before the output LC filter double
pole frequency FLC.
1 
1 
//  R2 +

VCOMP
sC2 
sC1 
=
=
1 
VOUT

R1//  R3 +

sC3 

FZ1 = 0.75 X FLC
Calculate the C2 by the equation:
1
C2 =
2 × π × R2 × FLC × 0.75

1
1

 

s +
×s +
R2 × C2  
R1 + R3) × C3 
(
R1 + R3

=
×
C1 + C2  
1
R1× R3 × C1 

s s +
× s +

R2
C1
C2
R3
C3
×
×
×

 

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Application Information(Cont.)
MOSFET Selection
4. Set the pole at the ESR zero frequency FESR:
The selection of the N-channel power MOSFETs is deter-
FP1 = FESR
mined by the RDS(ON), reverse transfer capacitance (CRSS),
and maximum output current requirement.The losses in
Calculate the C1 by the equation:
C2
C1 =
2 × π × R2 × C2 × FESR − 1
the MOSFETs have two components: conduction loss and
transition loss. For the upper and lower MOSFET, the
losses are approximately given by the following equations:
5. Set the second pole FP2 at the half of the switching
frequency and also set the second zero FZ2 at the output LC
PUPPER = IOUT2 (1+ TC)(RDS(ON))D + (0.5)(Iout)(VIN)(tsw)FSW
filter double pole FLC. The compensation gain should not
exceed the error amplifier open loop gain, check the
PLOWER = IOUT2 (1+ TC)(RDS(ON))(1-D)
compensation gain at FP2 with the capabilities of the error
amplifier.
where IOUT is the load current
TC is the temperature dependency of RDS(ON)
FSW is the switching frequency
FP2 = 0.5 X FS
FZ2 = FLC
tsw is the switching interval
D is the duty cycle
Combine the two equations will get the following component
calculations:
1 + s × ESR × COUT
GAINLC = 2
s × L × COUT + s × ESR × COUT + 1
Note that both MOSFETs have conduction losses while
the upper MOSFET includes an additional transition loss.
The switching internal, tsw, is the function of the reverse
transfer capacitance CRSS. Figure 7 illustrates the switch-
The poles and zero of this transfer functions are:
2 × π × L × COUT
of the RDS(ON) and can be extracted from the “RDS(ON) vs Temperature” curve of the power MOSFET.
R1
R3 =
FS
−1
2 × FLC
1
π × R3 × FS
GAIN (dB)
FZ1 FZ2
FP1
Voltage across
C3 =
VDS
FP2
Compensation
Gain
20log
(R2/R1)
20log
(VIN/ΔVOSC)
drain and source of MOSFET
FLC =
ing waveform internal of the MOSFET.
The (1+TC) term factors in the temperature dependency
1
tsw
FLC
FESR
PWM & Filter
Gain
Time
Figure 7. Switching Waveform Across MOSFET
Converter
Gain
Frequency(Hz)
Figure 6. Converter Gain and Frequency
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APW8722/A/B/C/D
Application Information (Cont.)
Layout Consideration
In any high switching frequency converter, a correct layout is important to ensure proper operation of the
- The drain of the MOSFETs (VIN and PHASE nodes) should
be a large plane for heat sinking.
regulator. With power devices switching at 300kHz,the
resulting current transient will cause voltage spike across
- The ROCSET resistance should be placed near the IC as
close as possible.
the interconnecting impedance and parasitic circuit
elements. As an example, consider the turn-off transition
APW8722
of the PWM MOSFET. Before turn-off, the MOSFET is carrying the full load current. During turn-off, current stops
flowing in the MOSFET and is free-wheeling by the lower
MOSFET and parasitic diode. Any parasitic inductance of
VCC
the circuit generates a large voltage spike during the
switching interval. In general, using short and wide printed
BOOT
circuit traces should minimize interconnecting imped
UGATE
ances and the magnitude of voltage spike. And signal
PHASE
and power grounds are to be kept separate till combined
using ground plane construction or single point
LGATE
grounding. Figure 8. illustrates the layout, with bold lines
indicating high current paths; these traces must be short
VIN
L
O
A
D
ROCSET
VOUT
Close to IC
and wide. Components along the bold lines should be
placed lose together. Below is a checklist for your layout:
Figure 8. Layout Guidelines
- Keep the switching nodes (UGATE, LGATE, and PHASE)
away from sensitive small signal nodes since these
nodes are fast moving signals. Therefore, keep traces
to these nodes as short as possible.
- The traces from the gate drivers to the MOSFETs (UG
and LG) should be short and wide.
- Place the source of the high-side MOSFET and the drain
of the low-side MOSFET as close as possible. Minimizing the impedance with wide layout plane between the
two pads reduces the voltage bounce of the node.
- Decoupling capacitor, compensation component, the
resistor dividers, and boot capacitors should be close
their pins. (For example, place the decoupling ceramic
capacitor near the drain of the high-side MOSFET as
close as possible. The bulk capacitors are also placed
near the drain).
- The input capacitor should be near the drain of the upper MOSFET; the output capacitor should be near the
loads. The input capacitor GND should be close to the
output capacitor GND and the lower MOSFET GND.
Copyright  ANPEC Electronics Corp.
Rev. A.3 - Jun., 2013
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APW8722/A/B/C/D
Package Information
SOP-8P
-T- SEATING PLANE < 4 mils
D
SEE VIEW A
h X 45o
E
E1
THERMAL
PAD
E2
D1
c
0.25
A1
A2
A
b
e
NX
aaa c
GAUGE PLANE
SEATING PLANE
L
VIEW A
S
Y
M
B
O
L
A
SOP-8P
INCHES
MILLIMETERS
MAX.
MIN.
MIN.
MAX.
1.60
0.063
0.000
0.15
0.006
A1
0.00
A2
1.25
b
0.31
0.51
0.012
0.020
c
0.17
0.25
0.007
0.010
D
4.80
5.00
0.189
0.197
0.049
D1
2.50
3.50
0.098
0.138
E
5.80
6.20
0.228
0.244
E1
3.80
4.00
0.150
0.157
E2
2.00
3.00
0.079
0.118
0.50
0.010
0.020
0.016
0.050
0oC
8oC
e
h
1.27 BSC
0.25
0.050 BSC
L
0.40
1.27
°
0oC
8oC
aaa
0.10
0.004
Note : 1. Followed from JEDEC MS-012 BA.
2. Dimension "D" does not include mold flash, protrusions or gate burrs.
Mold flash, protrusion or gate burrs shall not exceed 6 mil per side .
3. Dimension "E" does not include inter-lead flash or protrusions.
Inter-lead flash and protrusions shall not exceed 10 mil per side.
Copyright  ANPEC Electronics Corp.
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APW8722/A/B/C/D
Carrier Tape & Reel Dimensions
P0
P2
P1
A
B0
W
F
E1
OD0
K0
A0
A
OD1 B
B
T
SECTION A-A
SECTION B-B
H
A
d
T1
Application
A
H
T1
C
d
D
330.0±2.00
50 MIN.
12.4+2.00
-0.00
13.0+0.50
-0.20
1.5 MIN.
20.2 MIN.
P0
P1
P2
D0
D1
T
4.0±0.10
8.0±0.10
2.0±0.05
1.5+0.10
-0.00
1.5 MIN.
0.6+0.00
-0.40
SOP-8P
W
E1
12.0±0.30 1.75±0.10
A0
B0
6.40±0.20 5.20±0.20
F
5.5±0.05
K0
2.10±0.20
(mm)
Devices Per Unit
Package Type
Unit
Quantity
SOP-8P
Tape & Reel
2500
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APW8722/A/B/C/D
Taping Direction Information
SOP-8
USER DIRECTION OF FEED
Classification Profile
Copyright  ANPEC Electronics Corp.
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APW8722/A/B/C/D
Classification Reflow Profiles
Profile Feature
Sn-Pb Eutectic Assembly
Pb-Free Assembly
100 °C
150 °C
60-120 seconds
150 °C
200 °C
60-120 seconds
3 °C/second max.
3 °C/second max.
183 °C
60-150 seconds
217 °C
60-150 seconds
See Classification Temp in table 1
See Classification Temp in table 2
Time (tP)** within 5°C of the specified
classification temperature (Tc)
20** seconds
30** seconds
Average ramp-down rate (Tp to Tsmax)
6 °C/second max.
6 °C/second max.
6 minutes max.
8 minutes max.
Preheat & Soak
Temperature min (Tsmin)
Temperature max (Tsmax)
Time (Tsmin to Tsmax) (ts)
Average ramp-up rate
(Tsmax to TP)
Liquidous temperature (TL)
Time at liquidous (tL)
Peak package body Temperature
(Tp)*
Time 25°C to peak temperature
* Tolerance for peak profile Temperature (Tp) is defined as a supplier minimum and a user maximum.
** Tolerance for time at peak profile temperature (tp) is defined as a supplier minimum and a user maximum.
Table 1. SnPb Eutectic Process – Classification Temperatures (Tc)
Package
Thickness
<2.5 mm
≥2.5 mm
Volume mm
<350
235 °C
220 °C
3
Volume mm
≥350
220 °C
220 °C
3
Table 2. Pb-free Process – Classification Temperatures (Tc)
Package
Thickness
<1.6 mm
1.6 mm – 2.5 mm
≥2.5 mm
Volume mm
<350
260 °C
260 °C
250 °C
3
Volume mm
350-2000
260 °C
250 °C
245 °C
3
Volume mm
>2000
260 °C
245 °C
245 °C
3
Reliability Test Program
Test item
SOLDERABILITY
HOLT
PCT
TCT
HBM
MM
Latch-Up
Copyright  ANPEC Electronics Corp.
Rev. A.3 - Jun., 2013
Method
JESD-22, B102
JESD-22, A108
JESD-22, A102
JESD-22, A104
MIL-STD-883-3015.7
JESD-22, A115
JESD 78
22
Description
5 Sec, 245°C
1000 Hrs, Bias @ Tj=125°C
168 Hrs, 100%RH, 2atm, 121°C
500 Cycles, -65°C~150°C
VHBM≧2KV
VMM≧200V
10ms, 1tr≧100mA
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APW8722/A/B/C/D
Customer Service
Anpec Electronics Corp.
Head Office :
No.6, Dusing 1st Road, SBIP,
Hsin-Chu, Taiwan, R.O.C.
Tel : 886-3-5642000
Fax : 886-3-5642050
Taipei Branch :
2F, No. 11, Lane 218, Sec 2 Jhongsing Rd.,
Sindian City, Taipei County 23146, Taiwan
Tel : 886-2-2910-3838
Fax : 886-2-2917-3838
Copyright  ANPEC Electronics Corp.
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