SC2544

High Performance Wide Input Range Dual Synchronous Buck Controller POWER MANAGEMENT Description The SC2544 is a high performance dual PWM controller. It is designed to convert a wide ranged input voltage down to two independent output rails. The PWM operations of the two channels are 180 degree out of phase which can greatly reduce the size and the cost of the input capacitors. Synchronous Buck PWM topology and voltage mode control allow high efficiency operation, fast transient responses, and flexible component selection for easy designs. A 10V internal linear regulator provides the bias for the controller, and this voltage is optimized for gate drivers to deliver high efficiency. The power sequencing is fully supported including independent start up, and power good output. In the shut down mode the controller only draws 100nA from the supply. The controller also offers full protection features for the conditions of under voltage, over voltage, and the over current. There is no need for a current sensing resistor because the MOSFET on resistance is used for the sensing element. The switching frequency is adjustable from 100 kHz to 300 kHz. Two packages TSSOP-24 and MLPQ24 are offered. SC2544 Features Independent dual-outputs Wide input voltage range: 4.5V~28V Adjustable output voltage down to 0.75V Flexible power sequencing with enable and power good output Synchronous Buck topology with voltage mode control Out of phase operation to reduce cost of input capacitor 10V internal regulator for gate driver to deliver high efficiency P rogrammable switching frequency:100kHz~300kHz F ull protection: UVLO, OVP and programmable OCP No need for current sense resistor Low shutdown current (100nA typical) 24 lead TSSOP and MLPQ packages Fully WEEE and RoHS Compliant Applications Systems with 4.5V~28V input LCDTV and PDPTV Network and telecom systems Portable devices Typical Application Circuit SC2544 VIN+ VCC VO1 1 2 3 4 5 VIN+ 6 7 8 VO1 9 10 11 FB1 12 VIN VCC EN FB1 ERROUT1 SS1 ILIM1 BST1 DRVH1 PHASE1 DRVL1 PGND AGND ROSC PWRGD FB2 ERROUT2 SS2 ILIM2 BST2 DRVH2 PHASE2 DRVL2 PVCC 24 23 22 21 20 19 18 17 16 15 14 13 VCC FB2 VO2 VIN+ PWGRD FB2 ENABLE FB1 Pinout shown as TSSOP-24. Revision: August 10, 2005 1 www.semtech.com SC2544 POWER MANAGEMENT Absolute Maximum Ratings Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied. Parameter BST1, BST2 to PGND VIN to PGND ILIM1, ILIM2 and EN to PGND VC C and PVC C to PGND PGND to AGND BST1 to PH1, BST2 to PH2, D RVH1 to PH1, D RVH2 to PH2 D RVL1, D RVL2 to PGND PHASE, D RVL to AGND pulse (100nS), peak voltage All Other Pi ns to AGND Storage Temperature Range Juncti on Temperature Lead Temperature (Solderi ng) 10 Sec for TSSOP-24 Lead Temperature (IR Reflow) for MLPQ-24 Thermal Resi stance Juncti on to C ase TSSOP-24 MLP-24 Thermal Resi stance Juncti on to Ambi ent TSSOP-24 MLP-24 Symbol V b st Vin Maximum 38 28 VIN 14 +/- 0.3 -0.3 to 14 -0.3 to VC C -3 -0.3 to VC C U nits V V V V V V V V V o o TSTG TJ TLEAD θJC -60 to +150 -40 to +150 260 23 2 78 25 o C C C o C /W θJA o C /W Note: This device is ESD sensitive. Use of standard ESD handling precautions is required. Electrical Characteristics Unless specified: TA = 25 C, VIN=16V, Fs=200KHz . o Parameter U ndervoltage Lockout Start Threshold UVLO Hysteresi s Pow er Supply Operati ng C urrent (I IN-IPVCC) Vcc Regulated Vcc Load Regulati on Level Vcc Li ne Regulati on PVcc Operati ng C urrent D i sable Qui escent C urrent Main Sw itcher output Li ne Regulati on Load Regulati on Output Voltage Accuracy Test C onditions Min Typ Max U nit Vcc ri si ng Vcc falli ng 200 4.5 V mV SS1/SS2/EN =Hi gh, FS=200kHz VIN > 12V I_load=0~20mA Vi n=12~24V 200KHz, 1nF on HG, 1nF on LG EN=low 6.0 10 2 2 14 0.1 10 mA V % % mA 10 uA 5V