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APW7062A
Synchronous Buck PWM Controller
Features
* * *
Simple Single-Loop Control Design - Voltage-Mode PWM Control Fast Transient Response - Full 0-100% Duty Ratio Excellent Output Voltage Regulation - 0.8V Internal Reference - 1% Over Line Voltage and Temperature
General Description
The APW7062A is a voltage mode, synchronous PWM controller which drives dual N-Channel MOSFETs. It integrates the control, monitoring and protection functions into a single package, provides one controlled power outputs with under-voltage and over-current protection. APW7062A provide excellent regulation for output load variation. An internal 0.8V temperature-compensated reference voltage is designed to meet the requirement of low output voltage applications. It includes a 200kHz free-running triangle-wave oscillator that is adjustable from 70kHz to 800kHz. The power-on-reset (POR) circuit monitors the VCC, EN, OCSET input voltage to start-up or shutdown the IC. The over-current protection (OCP) monitors the output current by using the voltage drop across the upper MOSFET's RDS(ON), eliminating the need for a current sensing resistor. The under-voltage protection (UVP) monitors the voltage of FB pin for short-circuit protection. The over-current protection trip cycle the soft-start function until the fault events be removed. Under-voltage protection will shutdown the IC directly.
* * *
Over Current Fault Monitor - Uses Upper MOSFETs RDS (ON) Converter Can Source and Sink Current Small Converter Size - 200kHz Free-Running Oscillator - Programmable from 70kHz to 800kHz
* 14-Lead SOIC Package * Lead Free Available (RoHS Compliant)
Applications
* * * *
Graphic Cards DDR Memory Power Supply DDR Memory Termination Voltage Low-Voltage Distributed Power Supplies
Pinouts
RT OCSET SS NC FB EN GND 1 2 3 4 5 6 7 14 13 12 11 10 9 8 VCC PVCC LGATE PGND BOOT UGATE PHASE
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 - Mar., 2005 1 www.anpec.com.tw
APW7062A
Ordering and Marking Information
APW 7062A
L e a d F re e C o d e H a n d lin g C o d e Tem p. R ange P a ck ag e C o d e P ackage C ode K : S O P -1 4 O p e ra tin g J u n c tio n T e m p . R a n g e C : 0 to 7 0 C H a n d lin g C o d e TU : Tube TR : Tape & R eel L e a d F re e C o d e L : L e a d F re e D e v ic e B la n k : O rig in a l D e v ic e
A P W 7062A K :
A P W 7062A XXXXX
X X X X X - D a te C o d e
Notes ANPEC lead-free products contain molding compounds/die attach materials and 100% matte in plate termination finish; which are fully compliant with RoHS and compatible with both SnPb and lead-free soldiering operations. ANPEC lead-free products meet or exceed the lead-free requirements of IPC/JEDEC J STD-020C for MSL classification at lead-free peak reflow temperature.
Block Diagram
VCC OCSET G ND
EN
P ow er-O n R es et IOC S E T 200uA
vc c
BOOT UG A T E
ISS 10uA
SS
5.8V
S oft S tart
O .C .P C om parator
P HA S E
:2
50% V R E F
U .V .P C om parator
PVCC
PW M C om parator C om pens ation C irc uit G ate C ontrol
LGATE
E rror A m p V R EF O s c illator Triangle W ave
P G ND
FB
Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005
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APW7062A
Application Cicuit
12V R1 10R D1 12V 1N4148 R2 10K R4 NC 1 2 3 4 5 6 7 U1 APW7062A RT VCC OCSET PVCC SS LGATE NC PGND FB BOOT EN UGATE GND PHASE 14 13 12 11 10 9 8 C2 R3 1K 8 7 6 5 Q1 APM4220 1 2 3 8 7 6 5 R6 0R 4 1 2 3 Q2 APM4220 1.2V L2 2.2uH R7 NC D2 SR24 2A/40V C11 NC R8 1KF 1% + C9 1000uF 6.3V 30mR + C10 1000uF 6.3V 30mR C12 4.7uF C3 4.7uF + C4 470uF 16V 30mR + C5 470uF 16V 30mR L1 1uH + C6 100uF 16V C1 1uF
1nF
R5 2R2 C8 0.1uF
4
C7 0.1uF SHDN
R9 2KF 1%
VOUT = VREF x 1 +

R8 R9
Absolute Maximum Ratings
Symbol VCC VBOOT VPHASE VCC to GND BOOT to GND PHASE to GND Operating Junction Temperature TSTG TSDR VESD Storage Temperature Soldering Temperature (10 Seconds) Minimum ESD Rating Parameter Rating 30 30 30 0~150 -65 ~ 150 300 2 Unit V V V
o o o
C C C
KV
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APW7062A
Electrical Characteristics
APW7062A Symbol Parameter Test Conditions Min Typ Max VCC SUPPLY CURRENT ICC Nominal Supply Shutdown Supply POWER-ON-RESET Rising VCC Threshold Falling VCC Threshold Enable-Input Threshold Voltage Rising VOCSET Threshold OSCILLATOR Free Running Frequency Total Variation VOSC VREF VREF IUGATE RUGATE ILGATE RLGATE TD Ramp Amplitude Reference Voltage Tolerance Reference Voltage Upper Gate Source Upper Gate Sink Lower Gate Source Lower Gate Sink Dead Time FB Under Voltage IOCSET ISS OCSET Current Source Soft-Start Current VOCSET=4.5VDC 170 8 VBOOT=12V, VUGATE=6V IUGATE=0.3A PVCC=12V, VLGATE=6V ILGATE=0.3A VOUT=2.5V, IOUT=1A, RT=OPEN 550 650 REFERENCE VOLTAGE ACCURANCY -1 0.80 800 4 700 4 50 50 200 10 230 12 7 7 +1 % V mA mA ns % A A RT=OPEN, VCC=12 6K < RT to GND < 200K RT=OPEN 170 -15 1.9 200 230 +15 kHz % VP-P VOCSET=4.5VDC VOCSET=4.5VDC VOCSET=4.5VDC 8.8 0.8 1.27 2.0 10.4 V V V V EN=VCC; UGATE and LGATE Open EN=0V 2 250 350 mA A Unit
GATE DRIVERS
PROTECTION
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APW7062A
Functional Pin Description
RT (Pin1) This pin can adjust the switching frequency. Connect a resistor from RT to GND for increasing the switching frequency:
FS = 200kHz + 4.15 x 10 6 RT
(RT to GND, FS = 200kHz to 400kHz)
Conversely, connect a resistor from RT to VCC for decreasing the switching frequency:
3.51 x 10 7 RT
F S = 200kHz -
(RT to V CC , F S = 200kHz to 75kHz)
OCSET (Pin2) This pin serves two functions: a shutdown control and the setting of over current limit threshold. Pulling this pin below 1.27V will shutdown the controller, forcing the UGATE and LGATE signals to be at 0V. A resistor (Rocset) connected between this pin and the drain of the high side MOSFET will determine the over current limit. An internal 200uA current source will flow through this resistor, creating a voltage drop, which will be compared with the voltage across the high side MOSFET. The threshold of the over current limit is therefore given by:
SS (Pin3) Connect a capacitor from the pin to GND to set the soft-start interval of the converter. An internal 10uA current source charges this capacitor to 5.8V. The SS voltage clamps the error amplifier output, and Figure1 shows the soft-start interval. At t1, the SS voltage reaches the valley of the oscillator's triangle wave. The PWM comparator starts to generate a PWM signal to control logic, and the output is rising rapidly. Until the output is in regulation at t2, the clamp on the COMP is released. This method provides a rapid and controlled output voltage rise. When over current protection occurs, the VOUT is shutdown, and re-soft-start again, if the over current condition still exists in soft-start , the VOUT is shutdowned again, after the SS reaches 4.5V, the SS is discharged to zero. The soft-start is recurring until the over current condition is eliminated.
VOL TAGE VSOFT ST AR T
VOU T
VOSC(M IN )
E rro r Am p Ou tp u t
IPEAK =
IOCSET (200uA ) x ROCSET RDS(ON)
VSS= 1 .2 V
t0
t1
t2
t3
TIME
To avoid noise interference from switching transient, a delay time is designed in the OCP comparator. The over current protection is active only when the high side MOSFET is turned on longer than 300ns.
FIGURE1. SOFT-START INTERVAL
t2 =
CSS
ISS
x (VOSC(MIN)+ t1)
CSS x ISS V OUT SteadyState VIN
tSoftStart = t3 - t2 =
x VOSC
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APW7062A
Functional Pin Description (Cont.)
Where : t1=1.2V CSS = Soft Start Capacitor ISS = Soft Start Current = 10A VOSC(MIN) = Bottom of Oscillator = 1.35V VIN = Input Voltage Vosc = Peak to Peak Oscillator Voltage = 1.9V VOUTSteadyState = Steady State Output Voltage UGATE (Pin9) NC (Pin4) No internal connection. FB (Pin5) FB pin is the inverter input of the error amplifier. and it receives the feedback voltage from an external resistive divider across the output (VOUT). The output voltage is determined by:
VOUT = 0.8V x 1 +
GND (Pin7) Signal ground for the IC. PHASE (Pin8) This pin is connected to the source of the high-side MOSFET and is used to monitor the voltage drop across the high-side MOSFET for over-current protection.
Connect the pin to external MOSFET, and provides the gate drive for the upper MOSFET. BOOT (Pin 10) This pin provides the supply voltage to the high side MOSFET driver. For driving logic level N-channel MOSEFT, a bootstrap circuit can be used to create a suitable driver's supply. PGND (Pin11) Power ground for the gate diver. Connect the lower MOSFET source to this pin. LGATE (Pin 12) Connect the pin to external MOSFET, and provides the gate drive signal for the lower MOSFET.

ROUT RGND
where ROUT is the resistor connected from VOUT to FB and RGND is the resistor connected from FB to GND. If the FB voltage is under 50% VREF, because of the short circuit or other influence , it will cause the under voltage protection, and the device is shutdowned. Remove the error condition and restart the VCC voltage or pull the EN from low to high once, the device can be enabled again.
PVCC (Pin13) This pin provides a supply voltage for the lower gate drive, connect it to VCC pin in common use.
EN (Pin6) Pull the pin higher than 2V to enable the device, and pull the pin lower than 0.8V to shutdown the device. In shutdown, the SS is discharged and the UGATE and LGATE pins are held low. The EN pin is the opencollector, it will not be floating.
VCC (Pin14) This pin provides a supply voltage for the device, when VCC is above the rising threshold (10.4V), the device is turned on, conversely, VCC is below the falling threshold (8.8V), the device is turned off.
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APW7062A
Typical Characteristics
Power Up
Power Down
VCC=12V, VIN=12V VOUT=2.5V, L=2.2uH
VCC(5V/div)
VCC=12V, VIN=12V VOUT=2.5V, L=2.2uH
VCC(5V/div)
SS(2V/div) SS(2V/div)
VOUT(1V/div) VOUT(1V/div)
Time(10ms/div)
Time(10ms/div)
Enable (EN = VCC)
Shutdown (EN=GND)
EN(10V/div)
VCC=12V, VIN=12V VOUT=2.5V, L=2.2uH
EN(10V/div)
VCC=12V, VIN=12V VOUT=2.5V, L=2.2uH
SS(2V/div)
SS(2V/div)
VOUT(1V/div)
VOUT(1V/div)
Time(10ms/div)
Time(2ms/div)
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APW7062A
Typical Characteristics (Cont.)
Load Transient Response
VOUT(100mV/div) VCC=12V, VIN=12V VOUT=2.5V, L=2.2uH
Under Voltage Protection
VCC=12V, VIN=12V VOUT=2.5V, RT=Open L=2.2uH
VOUT(2V/div)
SS(5V/div) IOUT(2A/div) IL(10A/div)
UGATE(20V/div)
Time(20us/div)
Time(20us/div)
UGATE Rising
UGATE Falling
VCC=12V, VIN=12V VOUT=2.5V, RT=Open UGATE(10V/div)
VCC=12V, VIN=12V VOUT=2.5V, RT=Open UGATE(10V/div)
LGATE(10V/div) LGATE(10V/div)
Phase(10V/div)
Phase(10V/div)
Time(50ns/div)
Time(50ns/div)
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APW7062A
Typical Characteristics (Cont.)
UGATE Source Current vs. UGATE Voltage
1.4
VBOOT=12V
UGATE Sink Current vs. UGATE Voltage
1.2
VBOOT=12V
UGATE Source Current (A)
1.2 1 0.8 0.6 0.4 0.2 0 0 2 4 6 8 10 12
UGATE Sink Current (A)
1 0.8 0.6 0.4 0.2 0 0 2 4 6 8 10 12
UGATE Voltage (V)
UGATE Voltage (V)
LGATE Source Current vs. LGATE Voltage
1.4
PVCC=12V
LGATE Sink Current vs. LGATE Voltage
1.2
PVCC=12V
LGATE Source Current (A)
1.2 1 0.8 0.6 0.4 0.2 0 0 2 4 6 8 10 12
1
LGATE Sink Current (A)
0.8 0.6 0.4 0.2 0 0 2 4 6 8 10 12
LGATE Voltage (V)
LGATE Voltage (V)
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APW7062A
Typical Characteristics (Cont.)
Over Current Protection
VCC=12V, VIN=12V, VOUT=2.5V, ROCEST=1K, RT=Open, RDS(ON)=14m, IOUT=16.3A, L=2.2uH, LOUT=16.3A VOUT(1V/div)
RT Resistance vs. Switching Frequency
10000
RT pull up to 12V
RT Resistance (k)
1000
SS(5V/div)
100
IL(10A/div)
10
RT pull down to GND
UGATE(20V/div)
1 10 100 1000
Switching Frequency (kHz) Time(20ms/div)
Reference Voltage vs. Junction Temperature
0.8
Switching Frequency vs. Junction Temperature
220
VCC=12V RT=Open
Reference Voltage (V)
0.798
210
Switching Frequency
200 190 180 170 160
0.796
0.794
0.792
0.79 -40 -20 0 20 40 60 80 100 120
-40
-20
0
20
40
60
80
100 120
Junction Temperature (C)
Junction Temperature (C)
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APW7062A
Application Information
Component Selection Guidelines
Output Capacitor Selection The selection of COUT is determined by the required effective series resistance (ESR) and voltage rating rather than the actual capacitance requirement. Therefore select high performance low ESR capacitors that are intended for switching regulator applications. In some applications, multiple capacitors have to be paralled to achieve the desired ESR value. If tantalum capacitors are used, make sure they are surge tested by the manufactures. If in doubt, consult the capacitors manufacturer. Input Capacitor Selection The input capacitor is chosen based on the voltage rating and the RMS current rating. For reliable operation, select the capacitor voltage rating to be at least 1.3 times higher than the maximum input voltage. The maximum RMS current rating requirement is approximately IOUT/2 , where IOUT is the load current. During power up, the input capacitors have to handle large amount of surge current. If tantalum capacitors are used, make sure they are surge tested by the manufactures. If in doubt, consult the capacitors manufacturer. For high frequency decoupling, a ceramic capacitor between 0.1uF to 1uF can be connected between VCC and ground pin. Inductor Selection The inductance of the inductor is determined by the output voltage requirement. The larger the inductance, the lower the inductor's current ripple. This will translate into lower output ripple voltage. The ripple current and ripple voltage can be approximated by: IRIPPLE = VIN - VOUT Fs x L x VOUT VIN
11
VOUT = IRIPPLE x ESR where Fs is the switching frequency of the regulator. There is a tradeoff exists between the inductor's ripple current and the regulator load transient response time A smaller inductor will give the regulator a faster load transient response at the expense of higher ripple current and vice versa. The maximum ripple current occurs at the maximum input voltage. A good starting point is to choose the ripple current to be approximately 30% of the maximum output current. Once the inductance value has been chosen, select an inductor that is capable of carrying the required peak current without going into saturation. In some type of inductors, especially core that is make of ferrite, the ripple current will increase abruptly when it saturates. This will result in a larger output ripple voltage. MOSFET Selection The selection of the N-channel power MOSFETs are determined by the RDS(ON), reverse transfer capacitance (CRSS) and maximum output current requirement.The losses in the MOSFETs have two components: conduction loss and transition loss. For the upper and lower MOSFET, the losses are approximately given by the following : PUPPER = Iout2 (1+ TC)(RDS(ON))D + (0.5)(Iout)(VIN)(tsw)FS PLOWER = Iout2 (1+ TC)(RDS(ON))(1-D) where IOUT is the load current TC is the temperature dependency of RDS(ON) FS is the switching frequency tsw is the switching interval D is the duty cycle
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APW7062A
Application Information (Cont.)
Note that both MOSFETs have conduction losses while the upper MOSFET include an additional transition loss.The switching internal, tsw, is a function of the reverse transfer capacitance CRSS. Figure 3 illustrates the switching waveform internal of the MOSFET. The (1+TC) term is to factor in the temperature dependency of the RDS(ON) and can be extracted from the "RDS(ON) vs Temperature" curve of the power MOSFET. single point grounding. Figure 4 illustrates the layout, with bold lines indicating high current paths. Components along the bold lines should be placed close together. Below is a checklist for your layout:
* Keep the switching nodes (UGATE, LGATE and
PHASE) away from sensitive small signal nodes since these nodes are fast moving signals. There fore keep traces to these nodes as short as possible.
Layout Considerations
In high power switching regulator, a correct layout is important to ensure proper operation of the regulator. In general, interconnecting impedances should be minimized by using short, wide printed circuit traces. Signal and power grounds are to be kept separate and finally combined using ground plane construction or
* The ground return of CIN must return to the combine
COUT (-) terminal.
* Capacitor CBOOT should be connected as close to
the BOOT and PHASE pins as possible.
V DS
V IN
Voltage across drain and source of MO SFET
A P W 7062A
P GND LG AT E 11 12
C IN +
U UGATE 9 1
P HAS E 8
C OU T Q1 Q2 + L1
L O A D
t sw
Tim e
VO U T
Figure 3. Switching waveform across MOSFET
F igure 4. R ec om m ended Lay out D iagram
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APW7062A
Package Information
SOP - 14 (150mil)
0 . 01 5 x 4 5 A 0 . 0 10 L
D
Ee
B
Dim A A1 B C D E e H L
Millimeters Min. 1.477 0.102 0.331 0.191 8.558 3.82 1.274 5.808 0.382 0 6.215 1.274 8 0.228 0.015 0 Max. 1.732 0.255 0.509 0.2496 8.762 3.999 Min. 0.058 0.004 0.013 0.0075 0.336 0.150
A1
A
H
E
Inches Max. 0.068 0.010 0.020 0.0098 0.344 0.157 0.050 0.244 0.050 8
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APW7062A
Physical Specifications
Terminal Material Lead Solderability Packaging Solder-Plated Copper (Solder Material : 90/10 or 63/37 SnPb Meets EIA Specification RSI86-91, ANSI/J-STD-002 Category 3. 2500 devices per reel
(IR/Convection or VPR Reflow)
tp Critical Zone T L to T P
Reflow Condition
TP
Ram p-up
Temperature
TL Tsm ax
tL
Tsm in Ram p-down ts Preheat
25
t 25 C to Peak
Tim e
Classificatin Reflow Profiles
Profile Feature Average ramp-up rate (TL to TP) Preheat - Temperature Min (Tsmin) - Temperature Max (Tsmax) - Time (min to max) (ts) Time maintained above: - Temperature (TL) - Time (tL) Peak/Classificatioon Temperature (Tp) Time within 5C of actual Peak Temperature (tp) Ramp-down Rate Sn-Pb Eutectic Assembly 3C/second max. 100C 150C 60-120 seconds 183C 60-150 seconds See table 1 10-30 seconds Pb-Free Assembly 3C/second max. 150C 200C 60-180 seconds 217C 60-150 seconds See table 2 20-40 seconds
6C/second max. 6C/second max. 6 minutes max. 8 minutes max. Time 25C to Peak Temperature Notes: All temperatures refer to topside of the package .Measured on the body surface.
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APW7062A
Classificatin Reflow Profiles(Cont.)
Table 1. SnPb Entectic Process - Package Peak Reflow Tem peratures 3 3 Package Thickness Volum e m m Volum e m m <350 350 <2.5 m m 240 +0/-5C 225 +0/-5C 2.5 m m 225 +0/-5C 225 +0/-5C Table 2. Pb-free Process - Package Classification Reflow Tem peratures 3 3 3 Package Thickness Volum e mm Volum e mm Volum e mm <350 350-2000 >2000 <1.6 m m 260 +0C* 260 +0C* 260 +0C* 1.6 m m - 2.5 m m 260 +0C* 250 +0C* 245 +0C* 2.5 m m 250 +0C* 245 +0C* 245 +0C* *Tolerance: The device m anufacturer/supplier shall assure process com patibility up to and including the stated classification tem perature (this m eans Peak reflow tem perature +0C. For exam ple 260C+0C) at the rated MSL level.
Reliability Test Program
Test item SOLDERABILITY HOLT PCT TST ESD Latch-Up Method MIL-STD-883D-2003 MIL-STD-883D-1005.7 JESD-22-B,A102 MIL-STD-883D-1011.9 MIL-STD-883D-3015.7 JESD 78 Description 245C, 5 SEC 1000 Hrs Bias @125C 168 Hrs, 100%RH, 121C -65C~150C, 200 Cycles VHBM > 2KV, VMM > 200V 10ms, 1tr > 100mA
Carrier Tape & Reel Dimension
t Po P P1 D
E
F W
Ao
D1
Ko
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APW7062A
Carrier Tape & Reel Dimension
T2
J C A B
T1
Application
SOP-14 (150mil)
A 330REF F 7.5
C 13.0 + 0.5 100REF - 0.2 D D1 0.50 + 0.1 1.50 (MIN)
B
J 2 0.5 Po 4.0
T1
T2
16.5REF 2.5 025 P1 2.0 Ao 6.5
W 16.0 0.3 Ko 2.10
P 8 t 0.30.05
E 1.75
(mm)
Cover Tape Dimensions
Application SOP- 14 Carrier Width 24 Cover Tape Width 21.3 Devices Per Reel 2500
Customer Service
Anpec Electronics Corp. Head Office : 5F, No. 2 Li-Hsin Road, SBIP, Hsin-Chu, Taiwan, R.O.C. Tel : 886-3-5642000 Fax : 886-3-5642050 Taipei Branch : 7F, No. 137, Lane 235, Pac Chiao Rd., Hsin Tien City, Taipei Hsien, Taiwan, R. O. C. Tel : 886-2-89191368 Fax : 886-2-89191369
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