AP2002

AP2002 ANACHIP | Alldatasheet

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Synchronous PWM Controller This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sale of the product. Rev. 0.2 Apr 14, 2004 „ Features - Single or Dual Supply Application - 0.8V + 1.0% Voltage Reference. - Fast transient response. - Synchronous operation for high efficiency (95%) - On-chip power good, OVP protect. - Small size with minimum external components - Soft Start and enable functions - Industrial temperature range - Under Voltage Lockout function - SOP-14L package „ Applications - Microprocessor core supply - Low cost synchronous applications - Voltage Regulator Modules (VRM) - DDR termination supplies - Networking power supplies - Sequenced power supplies „ General Description The AP2002 is a low-cost, full featured, and synchronous voltage-mode controller designed for use in single ended power supply applications where efficiency is of primary concern. This synchronous operation allows the elimination of heat sinks in many applications. The AP2002 is ideal for implementing DC/DC converters that is needed for the power advanced microprocessors in low cost systems, or in distributed power applications where efficiency is important. Internal level-shift, high-side drive circuitry, and preset shoot-thru control, allows the use of inexpensive N-channel power switches. AP2002 features include temperature compensated voltage reference, an internal 200Khz virtual frequency oscillator, under voltage lockout protection, soft-start function and current sense comparator circuitry. Power good signaling, shutdown, and over voltage protection are also provided by AP2002. „ Pin Assignment SOP-14L (Top View) VCC PWRGD OVP OCSET PHASE DRVH PGND DRVL BSTL BSTH SENSE COMP GND SS/SHDN AP2002 7 8 „ Ordering Information AP2002 X X X Package Packing S: SOP-14L Blank : Tube A : Taping Lead Free Blank : Normal L : Lead Free Package „ Pin Descriptions Name Description VCC Chip supply voltage PWRGD Logic high indicates correct output voltage (open drain output) OVP Over voltage protection OCSET Sets the converter over-current trip point PHASE Input from the phase node between the MOSFETs DRVH High side driver output PGND Power ground DRVL Low side driver output BSTL Bootstrap, low side driver BSTH Bootstrap, high side driver SENSE Voltage sense input COMP Compensation pin SS/ SHDN Soft start, a capacitor to ground sets the slow start time GND Signal ground

Synchronous PWM Controller Anachip Corp. „ Block Diagram DRVH Cross Current Control DRVL VCC GND PWRGD SS/SHDN OVP SENSE OCSET PHASE BSTH DRVH BSTL PGND DRVL 200uA Over Current One-ShotOscillator PWM Foult Ob S R 0.6V 0.5V Vcc 10uA 2uA Vbg Error Amp Vcc Under Voltage Vbg +10% - 10% +20% 0.8V VCC COMP „ Absolute Maximum Ratings Symbol Parameter Max. Unit VIN VCC, BSTL to GND -1 to 14 V PGND to GND + 0.5 V PHASE to GND -1 to 18 V VPHASE BSTH to PHASE 14 V ΘJC Thermal Resistance Junction to Case 45 oC/W ΘJA Thermal Resistance Junction to Ambient 115 oC/W TOP Operating Temperature Range -40 to +85 oC TST Storage Temperature Range -65 to +150 oC TLEAD Lead Temperature (Soldering) 10 Sec. 300 oC

Synchronous PWM Controller Anachip Corp. „ Electrical Characteristics Unless specified: VCC = 4.75V to 12.6V; GND = PGND = 0V; FB = VO; VBSTL = 12V; VBSTH-PHASE = 12V; TJ = 25oC Symbol Parameter Conditions Min. Typ. Max. Unit Power Supply VCC Supply Voltage V CC 4.2 12.6 V ICC Supply Current 6 10 mA ∆VLINE Line Regulation VO = 2.5V 0.5 % Error Amplifier AOL Gain (A OL) 50 dB IB Input Bias 5 8 uA Oscillator FOSC Oscillator Frequency 180 200 220 KHz DCMAX Oscillator Max Duty Cycle 90 95 % MOSFET Drivers IDRVH DRVH Source/Sink VBSTH – VDRVH =4.5V VDRVH – VPHASE = 2V 1 A IDRVL DRVL Source/Sink VBSTH – VDRVL = 4.5V VDRVL – VPGND = 2V 1 A Protection DTH OVP Threshold 20 % IOVP OVP Source Current V OVP = 3V 10 mA DPG Power Good Threshold 88 112 % TDEAD Dead Time 45 100 nS IOCSET Over Current Set Isink 2.0V < VOCSET < 12V 180 200 220 uA Reference Reference Voltage 0.792 0.8 0.808 V VREF Accuracy 0oC to 70oC -1 + 1 % Soft Start ISSC Charge Current V SS = 1.5V 8.0 10 12 uA ISSD Discharge Current V SS = 1.5V 1.3 2 2.7 uA Under voltage lockout (UVLO) VUT Upper threshold voltage (VCC) 4.2 4.4 V VLWT Lower threshold voltage (VCC) 4.0 V VHT Hysteresis (V CC) IO(REF) = 0.1mA TA = 25ºC 200 mV Note 1. Specification refers to Typical Application Circuit. Note 2. This device is ESD sensitive. Use of standard ESD handling precautions is required.

Synchronous PWM Controller Anachip Corp. „ Typical Application Circuit (1) 0.1 0.1R2 10k +5V PWRGD OVP R31k Option VCC GND PWRGD SS/SHDN OVP COMP OCSET SENSE PHASE BSTH DRVH BSTL PGND DRVL

0.1 SHDN

1.2O 1.2O PFD3000 PFD3000 3.3uH C100.1 C11 680/ 16V C12 680/ 16V C13 680/ 16V C14 680/ 16V Vout=2.5V VIN 5V/12V C8C7C6 680/ 16V 0.1 120 270* Note: *Vout =Vref x (1+R9/R8) 5V & 12V dual input circuit 680/ 16V 680/ 16V +12V 47k 18nF R10 4.7O R7 C9 0.1u (2) 0.1 0.1R2 10k +5V PWRGD OVP Option VCC GND PWRGD SS/SHDN OVP COMP OCSET SENSE PHASE BSTH DRVH BSTL PGND DRVL 1.2 1.2 PFD3000 PFD3000 0.1 L1 3.3uH C10 0.1 C11 680/ 16V C12 C13 C14 Vout=2.5V* VIN 5V or 12V 680/ 16V 680/ 16V 680/ 16V 0.1 120 270* Note: * Vout=Vref x (1+R9/R8) 5V or 12V input with Bootstrapped BSTH 47k 18nF 680/ 16V 680/ 16V 680/ 16V R10 4.7 Ω Ω Ω 0.1u

Synchronous PWM Controller Anachip Corp. „ Function Description Synchronous Buck Converter Primary VCORE power is provided by a synchronous, voltage-mode pulse width modulated (PWM) controller. This section has all the features required to build a high efficiency synchronous buck converter, including “Power Good” flag, shutdown, and cycle-by-cycle current limit. The output voltage of the synchronous converter is set and controlled by the output of the error amplifier. The external resistive divider reference voltage is derived from an internal trimmed band-gap voltage reference. The inverting input of the error amplifier receives its voltage from the SENSE pin. The internal oscillator uses an on-chip capacitor and trimmed precision current sources to set the oscillation frequency to 200KHz. The triangular output of the oscillator sets the reference voltage at the inverting input of the comparator. When the oscillator output voltage drops below the error amplifier output voltage, the comparator output goes high. This pulls DRVL low, turning off the low-side FET, and DRVH is pulled high, turning on the high-side FET (once the cross-current control allows it). When the oscillator voltage rises back above the error amplifier output voltage, the comparator output goes low. This pulls DRVH low, turning off the high-side FET, and DRVL is pulled high, turning on the low-side FET (once the cross-current control allows it). As SENSE increases, the output voltage of the error amplifier decreases. This causes a reduction in the on-time of the high-side MOSFET connected to DRVH, hence lowering the output voltage. Under Voltage Lockout The under voltage lockout circuit of the AP2002 assures that the high-side MOSFET driver outputs remain in the off state whenever the supply voltage drops below set parameters. Lockout occurs if V CC falls below 4.1V. Normal operation resumes once V CC rises above 4.2V. Over-Voltage Protection The over-voltage protection pin (OVP) is high only when the voltage at SENSE is 20% higher than the target value programmed by the external resistor divider. The OVP pin is internally connected to a PNP’s collector. Power Good The power good function is to confirm that the regulator outputs are within +/- 10% of the programmed level. PWRGD remains high as long as this condition is met. PWRGD is connected to an internal open collector NPN transistor. Soft Start Initially, SS/ SHDN sources 10uA of current to charge an external capacitor. The outputs of the error amplifiers are clamped to a voltage proportional to the voltage on SS/SHDN . This limits the on-time of the high-side MOSFET, thus leading to a controlled ramp-up of the output voltages. R DS(ON) Current Limiting The current limit threshold is setting by connecting an external resistor from V CC supply to OCSET. The voltage drop across this resistor is due to the 200uA internal sink sets the voltage at the pin. This voltage is compared to the voltage at the PHASE node. This comparison is made only when the high-side drive is high to avoid false current limit triggering due to un-contributing measurements from the MOSFETs off-voltage. When the voltage at PHASE is less than the voltage at OCSET, an over-current condition occurs and the soft start cycle is initiated. The synchronous switch turns off and SS/ SHDN starts to sink 2uA. When SS/ SHDN reaches 0.8V, it then starts to source 10uA and a new cycle begins.

Synchronous PWM Controller Anachip Corp. „ Function Description (Continued) Hiccup Mode During power up, the SS/ SHDN pin is internally pulled low until V CC reaches the under-voltage lockout level of 4.2V. Once V CC has reached 4.2V, the SS/ SHDN pin is released and begins to source 10uA of current to the external soft-start capacitor. As the soft-start voltage rises, the output of the internal error amplifier is clamped to this voltage. When the error signal reaches the level of the internal triangular oscillator, which swings from 1V to 2V at a fixed frequency of 200KHz, switching occurs. As the error signal crosses over the oscillator signal, the duty cycle of the PWM signal continues to increase until the output comes into regulation. If an over-current condition has not occurred the soft-start voltage will continue to rise and level off at about 2.2V. An over-current condition occurs when the high-side drive is turned on, but the PHASE node does not reach the voltage level set at the OCSET pin. The PHASE node is sampled only once per cycle during the vally of the triangular oscillator. Once an over-current occurs, the high-side drive is turned off and the low-side drive turns on and the SS/ SHDN pin begins to sink 2uA. The soft-start voltage will begin to decrease as the 2uA of current discharge the external capacitor. When the soft-start voltage reaches 0.8V, the SS/ SHDN pin will begin to source 10uA and begin to charge the external capacitor causing the soft-start voltage to rise again. Again, when the soft-start voltage reaches the level of the inte rnal oscillator, switching will occur. If the over-current condition is no longer present, normal operation will continue. If the over-current condition is still present, the SS/ SHDN pin will again begin to sink 2uA. This cycle will continue indefinitely until the over-current condition is removed. In conclusion, above is shown a typical “12V Application Circuit” which has a BSTH voltage derived by bootstrapping input voltage to the PHASE node through diode D1. This circuit is very useful in cases where only input power of 5V(or 12V) is available. In order to prevent substrate glitching, a small-signal diode should be placed in close proximity to the chip with cathode connected to PHASE and anode connected to PGND. „ Marking Information ( Top View ) SOP-14L AC AP2002 YY WW X X Logo ID code: internal Year: "01" = 2001 "02" = 2002 Xth week: 01~52 Part No. Blank: normal L: Lead Free Package

Synchronous PWM Controller Anachip Corp. „ Package Information (1) Package Type: SOP-14L 0.015x45o 7o(4x) C Detail A D 7o (4x) y e b A2A1 A Pin 1 indent E L 0.010 Detail A Θ Gage Plane A1 0.10 - 0.250 0.0040 - 0.0100 θ 0O - 8O 0 O - 8O