APW7062A Synchronous Buck PWM Controller Features 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. 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 • 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 Pinouts DDR Memory Termination Voltage Low-Voltage Distributed Power Supplies RT 1 14 VCC OCSET 2 13 PVCC SS 3 12 LGATE NC 4 11 PGND FB 5 10 BOOT EN 6 9 UGATE GND 7 8 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 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 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 A P W 7062A XXXXX A P W 7062A K : 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 P ow er-O n R es et EN IO C S E T 200uA vc c BOOT UG A T E IS S 10uA O .C .P C om parator S oft S tart SS P HA S E 5.8V U .V .P C om parator :2 50% V R E F PVCC PW M C om parator G ate C ontrol LGATE C om pens ation C irc uit E rror A m p P G ND V R EF O s c illator Triangle W ave FB Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 RT 2 www.anpec.com.tw APW7062A Application Cicuit 12V C1 R1 10R 1uF D1 12V R2 10K R4 NC RT VCC OCSET PVCC SS LGATE NC PGND FB BOOT EN UGATE GND PHASE 1uH 1K U1 APW7062A 1 2 3 4 5 6 7 L1 R3 1N4148 14 13 12 11 10 9 8 C2 R5 8 7 6 5 1nF 1 2 3 + C6 100uF 16V 1.2V L2 8 7 6 5 SHDN R6 + C5 470uF 16V 30mR Q1 APM4220 4 2R2 C8 0.1uF C7 0.1uF + C4 470uF 16V 30mR C3 4.7uF 2.2uH R7 NC Q2 APM4220 4 1 2 3 0R D2 SR24 2A/40V C11 NC R8 1KF 1% + C9 1000uF 6.3V 30mR + C10 1000uF 6.3V 30mR C12 4.7uF R9 2KF 1% VOUT = VREF × 1 + R8 R9 Absolute Maximum Ratings Symbol Rating Unit VCC to GND 30 V VBOOT BOOT to GND 30 V VPHASE PHASE to GND 30 VCC Parameter Operating Junction Temperature TSTG Storage Temperature 0~150 -65 ~ 150 o o TSDR Soldering Temperature (10 Seconds) 300 VESD Minimum ESD Rating ±2 Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 3 V o C C C KV www.anpec.com.tw APW7062A Electrical Characteristics APW7062A Symbol Parameter Test Conditions Min Typ Max Unit VCC SUPPLY CURRENT ICC Nominal Supply Shutdown Supply EN=VCC; UGATE and LGATE Open EN=0V 2 250 mA 350 µA 10.4 V POWER-ON-RESET Rising VCC Threshold VOCSET=4.5V DC Falling VCC Threshold VOCSET=4.5V DC 8.8 Enable-Input Threshold Voltage VOCSET=4.5V DC 0.8 Rising VOCSET Threshold V 2.0 1.27 V V OSCILLATOR ∆VOSC Free Running Frequency RT=OPEN, VCC=12 170 Total Variation 6KΩ < RT to GND < 200KΩ -15 Ramp Amplitude RT=OPEN 200 230 kHz +15 % 1.9 VP-P REFERENCE VOLTAGE ACCURANCY ∆VREF VREF Reference Voltage Tolerance -1 Reference Voltage +1 % 0.80 V 800 mA GATE DRIVERS IUGATE Upper Gate Source VBOOT=12V, VUGATE=6V RUGATE Upper Gate Sink IUGATE=0.3A ILGATE Lower Gate Source PVCC=12V, VLGATE=6V RLGATE Lower Gate Sink ILGATE=0.3A 4 Dead Time VOUT=2.5V, IOUT=1A, RT=OPEN 50 ns 50 % TD 650 4 550 7 700 Ω mA 7 Ω PROTECTION FB Under Voltage IOCSET ISS OCSET Current Source VOCSET=4.5V DC Soft-Start Current Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 4 170 200 230 µA 8 10 12 µA www.anpec.com.tw APW7062A Functional Pin Description 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. 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 × 10 6 RT (RT to GND, FS = 200kHz to 400kHz) Conversely, connect a resistor from RT to VCC for decreasing the switching frequency: F S = 200kHz − 3.51 × 10 7 RT (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: VOL TAGE VSO F T ST AR T VOU T E rro r Am p Ou tp u t VOSC ( M IN ) IPEAK = IOCSET (200uA ) × ROCSET VSS= 1 .2 V RDS(ON) t0 t2 TIME t3 FIGURE1. SOFT-START INTERVAL 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. Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 t1 t2 = CSS ISS × (VOSC(MIN)+ t1) tSoftStart = t3 − t2 = 5 CSS × ISS V OUT SteadyState VIN × ∆VOSC www.anpec.com.tw APW7062A Functional Pin Description (Cont.) GND (Pin7) Where : t1=1.2V CSS = Soft Start Capacitor Signal ground for the IC. ISS = Soft Start Current = 10µA 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. 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. Connect the pin to external MOSFET, and provides 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: BOOT (Pin 10) VOUT = 0.8V × 1 + the gate drive for the upper MOSFET. 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. ROUT RGND PGND (Pin11) Power ground for the gate diver. Connect the lower MOSFET source to this pin. where ROUT is the resistor connected from VOUT to FB and RGND is the resistor connected from FB to GND. LGATE (Pin 12) 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. Connect the pin to external MOSFET, and provides the gate drive signal for the lower MOSFET. 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. Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 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. 6 www.anpec.com.tw APW7062A Typical Characteristics Power Up V CC (5V/div) Power Down VCC=12V, VIN=12V VOUT=2.5V, L=2.2uH V CC(5V/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(10ms/div) Enable (EN = VCC) EN(10V/div) Shutdown (EN=GND) EN(10V/div) VCC=12V, V IN=12V VOUT=2.5V, L=2.2uH SS(2V/div) SS(2V/div) V OUT(1V/div) VOUT(1V/div) Time(10ms/div) Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 VCC=12V, VIN=12V VOUT=2.5V, L=2.2uH Time(2ms/div) 7 www.anpec.com.tw APW7062A Typical Characteristics (Cont.) Load Transient Response Under Voltage Protection VCC=12V, VIN=12V VOUT=2.5V, RT=Open L=2.2uH VCC=12V, VIN=12V VOUT=2.5V, L=2.2uH VOUT(100mV/div) 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 VCC=12V, VIN=12V VOUT=2.5V, RT=Open UGATE(10V/div) UGATE(10V/div) LGATE(10V/div) LGATE(10V/div) Phase(10V/div) Phase(10V/div) Time(50ns/div) Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 Time(50ns/div) 8 www.anpec.com.tw APW7062A Typical Characteristics (Cont.) UGATE Source Current vs. UGATE Voltage UGATE Sink Current vs. UGATE Voltage 1.2 1.4 VBOOT=12V 1.2 UGATE Sink Current (A) UGATE Source Current (A) VBOOT=12V 1 0.8 0.6 0.4 0.2 0 1 0.8 0.6 0.4 0.2 0 0 2 4 6 8 10 12 0 2 6 8 10 12 UGATE Voltage (V) UGATE Voltage (V) LGATE Source Current vs. LGATE Voltage LGATE Sink Current vs. LGATE Voltage 1.2 1.4 PVCC=12V PVCC=12V 1.2 1 LGATE Sink Current (A) LGATE Source Current (A) 4 1 0.8 0.6 0.4 0.2 0.8 0.6 0.4 0.2 0 0 0 2 4 6 8 10 0 12 LGATE Voltage (V) Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 2 4 6 8 10 12 LGATE Voltage (V) 9 www.anpec.com.tw APW7062A Typical Characteristics (Cont.) RT Resistance vs. Switching Frequency Over Current Protection VCC=12V, VIN=12V, VOUT=2.5V, ROCEST=1KΩ, RT=Open, RDS(ON)=14mΩ, IOUT=16.3A, L=2.2uH, LOUT=16.3A 10000 VOUT(1V/div) RT Resistance (kΩ) RT pull up to 12V SS(5V/div) IL(10A/div) UGATE(20V/div) 1000 100 RT pull down to GND 10 1 10 100 1000 Switching Frequency (kHz) Time(20ms/div) Switching Frequency vs. Junction Temperature Reference Voltage vs. Junction Temperature 0.8 220 210 0.798 Switching Frequency Reference Voltage (V) VCC =12V RT=Open 0.796 0.794 0.792 200 190 180 170 160 0.79 -40 -20 0 20 40 60 80 -40 100 120 Junction Temperature (°C) Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 -20 0 20 40 60 80 100 120 Junction Temperature (°C) 10 www.anpec.com.tw APW7062A Application Information Component Selection Guidelines ∆VOUT = IRIPPLE x ESR 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. where Fs is the switching frequency of the regulator. 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. 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. 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. MOSFET Selection The selection of the N-channel power MOSFETs are determined by the RDS(ON), reverse transfer capacitance 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: PUPPER = Iout2 (1+ TC)(RDS(ON))D + (0.5)(Iout)(VIN)(tsw)FS IRIPPLE = VIN - VOUT Fs x L x VOUT VIN Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 11 (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 : 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 www.anpec.com.tw 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 • The ground return of CIN must return to the combine 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 COUT (-) terminal. • Capacitor CBOOT should be connected as close to the BOOT and PHASE pins as possible. V DS Voltage across drain and source of MO SFET V IN C IN A P W 7062A P GND LG AT E 11 12 U UGATE 9 1 P HAS E 8 t sw Tim e Figure 3. Switching waveform across MOSFET Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 + L O A D C OU T Q1 Q2 + L1 VO U T F igure 4. R ec om m ended Lay out D iagram 12 www.anpec.com.tw APW7062A Package Information E H 0 . 01 5 x 4 5 SOP – 14 (150mil) A 0 . 0 10 A1 A D Ee B L Dim A A1 B C D E e H L θ° Millimeters Min. 1.477 0.102 0.331 0.191 8.558 3.82 Inches 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 6.215 1.274 8° 0.228 0.015 0° 1.274 5.808 0.382 0° Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 Max. 0.068 0.010 0.020 0.0098 0.344 0.157 0.050 13 0.244 0.050 8° www.anpec.com.tw 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 Reflow Condition (IR/Convection or VPR Reflow) tp TP Critical Zone T L to T P Temperature Ram p-up TL tL Tsm ax 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 5°C of actual Peak Temperature (tp) Ramp-down Rate Sn-Pb Eutectic Assembly Pb-Free Assembly 3°C/second max. 3°C/second max. 100°C 150°C 60-120 seconds 150°C 200°C 60-180 seconds 183°C 60-150 seconds 217°C 60-150 seconds See table 1 See table 2 10-30 seconds 20-40 seconds 6°C/second max. 6°C/second max. 6 minutes max. 8 minutes max. Time 25°C to Peak Temperature Notes: All temperatures refer to topside of the package .Measured on the body surface. Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 14 www.anpec.com.tw 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/-5°C 225 +0/-5°C ≥2.5 m m 225 +0/-5°C 225 +0/-5°C 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 +0°C* 260 +0°C* 260 +0°C* 1.6 m m – 2.5 m m 260 +0°C* 250 +0°C* 245 +0°C* ≥2.5 m m 250 +0°C* 245 +0°C* 245 +0°C* *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 +0°C. For exam ple 260°C+0°C) 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 245°C, 5 SEC 1000 Hrs Bias @125°C 168 Hrs, 100%RH, 121°C -65°C~150°C, 200 Cycles VHBM > 2KV, VMM > 200V 10ms, 1tr > 100mA Carrier Tape & Reel Dimension t E D P Po P1 F W Ao Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 D1 15 Ko www.anpec.com.tw APW7062A Carrier Tape & Reel Dimension T2 J C A B T1 Application A 330REF SOP-14 (150mil) F 7.5 B C 13.0 + 0.5 100REF - 0.2 D D1 φ0.50 + 0.1 φ1.50 (MIN) J T1 2 ± 0.5 T2 16.5REF 2.5 ± 025 W 16.0 ± 0.3 P E 8 1.75 Po P1 Ao Ko t 4.0 2.0 6.5 2.10 0.3±0.05 (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 Copyright ANPEC Electronics Corp. Rev. A.3 - Mar., 2005 16 www.anpec.com.tw