BI-Phase/Dual Controller

www.DataSheet4U.com BI-Phase/Dual Controller POWER MANAGEMENT Description The SC2450 can be configured as a dual converter or a bi-phase converter for high current applications. The part is designed for point of use power supplies with 10-30V nominal backplane power sources. Multiple supplies can be synchronized together to prevent low frequency harmonics on the backplane. The power dissipation is controlled using a novel low voltage supply technique, allowing high speed and integration, with the high drive currents to ensure low MOS.ET switching loss. The use of high speed switching circuits allows very narrow PWM outputs down to 15:1 voltage ratios. Single pin compensation for each channel simplifies development as well as reducing external pin count. Capable of driving MOS.ETs via external driver transistors for phase currents beyond 20A. SC2450 .eatures K K K K K K K K K Selectable dual output or bi-phase operation Direct drive for N-channel MOS.ETs Undervoltage lockout Synchronization to external clock Multi-converter synchronization Soft start .ast transient response Max duty cycle 45% Output over voltage protection Applications K Power supplies for advanced telecoms/datacoms K SO IP, Ethernet and PABX power supplies Typical Application Circuit Revision 2, August 2001 1 www.semtech.com SC2450 POWER MANAGEMENT Absolute Maximum Ratings Parameter Supply Voltage Voltage on BST Pins Oscillator Frequency VC C Thermal Resistance Junction to Case Thermal Resistance Junction to Ambient Operating Temperature Range Storage Temperature Range Lead Temperature (Soldering) 10 seconds θJC θJ A TA TSTG TLEAD (1) Symbol VIN V BST Maximum 34 42 2 8 25 80 -40 to +85 -55 to +150 300 Units V V MHz V °C/W °C/W °C °C °C Note: (1) Maximum frequency and maximum supply voltage could cause excessive power dissipation in the part. Electrical Characteristics Unless specified VIN = 24V, TA = 25°C PARAMETER Supply Voltage, VIN Supply Current Under Voltage Lockout UVLO Hysteresis Voltage Regulator Pre Regulator Voltage Bgout Voltage Bgout Impedance REGDRV Pin Sink Current Error Amp Input Offset Voltage Input Impedance Linear Transconductance Internal Oscillator Frequency Frequency Ramp Valley to Peak Ramp Valley to Peak CONDITIONS ENABLE = 0 MIN 10 TYP 30 5.8 400 MAX 30 40 UNITS V mA V mV 6 CREF = 4.7nF IREGDRV 0.99 1 3 5 7 1.01 V V KΩ mA 10 5 .002 mV KΩ A/V RREF = 30K RREF = 60K VIN = 12V VIN = 24V 1 500 1.5 3 MHz kHz V V  2001 Semtech Corp. 2 www.semtech.com SC2450 POWER MANAGEMENT Electrical Characteristics (Cont.) Unless specified VIN = 24V, TA = 25°C PARAMETER External Clock Detect Time Unlock Time Frequency Range High Side Gate Drive Max Duty Cycle Peak Source Peak Sink Low Side Gate Drive Peak Source Peak Sink Sync Drive Timing Min Non-overlap PWM Match Logic Input Pins Input Bias Current Logic Threshold FB2 Disable Threshold Over Current Protection OCP Threshold OC+ I/P Bias Current OC- I/P Bias Current Over Voltage Protection OVP Threshold Thermal Shutdown Note: CONDITIONS Rise Time < 50ns MIN TYP MAX 2 UNITS µs µs MHz % A A A A ns 10 0.3 45 CLOAD = 10nF CLOAD = 10nF CLOAD = 10nF CLOAD = 10nF CLOAD = 1nF Fet Drive < 1V 50% Duty Cycle, FOSC = 1MHz VIN = 0 - 5V 20 -1 1 1 2 2 50 50 1 1 % -10 0.8 VCC - 0.7V 103 115 700 50 10 µA V V 127 mV µA µA VIN = 24V 120 150 % °C (1) This device is ESD sensitive. Use of standard ESD handling precautions is required.  2001 Semtech Corp. 3 www.semtech.com SC2450 POWER MANAGEMENT Pin Configuration Top View Ordering Information Part Number(1) SC2450ISWTR S C 2450E V B PACKAGE TAMB (TA) SO-28 -40 - +85°C SC2450 Evaluation Board Note: (1) Only available in tape and reel packaging. A reel contains 1000 devices. (28-Pin SOIC) Block Diagram  2001 Semtech Corp. 4 www.semtech.com SC2450 POWER MANAGEMENT Pin Descriptions Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Pin Name FB1 COMP1 NC BG FB2 COMP2 REGDRV ENABLE PHASE2 DRVH2 BSTH2 DRVL2 BSTL2 VCC BSTL1 DRVL1 BSTH1 DRVH1 PHASE1 PGND OC+ OC-2 OC-1 EXTCLK CLKOUT NC AGND RREF Pin Function Feedback for channel 1. Compensation for channel 1. No connection. 1V reference for error amplifiers, 3K source impedance. Feedback for channel 2. Compensation for channel 2. Regulator drive for external pass transistor. Enable threshold is 2.05 V, connect to ground to disable. Phase node input for channel 2. Gate drive for high side channel 2. Bootstrap input for high side channel 2. Gate drive for low side channel 2. Supply for low side channel 2. Pre-regulated IC power supply. Supply for low side channel 1. Gate drive for low side channel 1. Bootstrap input for high side channel 1. Gate drive for high side channel 1. Phase node input for high side channel 1. Power ground. Overcurrent comparator inverting input. Overcurrent comparator non-inverting input for channel 2. Overcurrent comparator non-inverting input for channel 1. External clock, converter locks to this input when a valid signal is present. Clock out, logic level drive to provide synchronizing signal for other converters. No connection. Analog ground. External reference resistor for internal oscillator and ramp generator.  2001 Semtech Corp. 5 www.semtech.com SC2450 POWER MANAGEMENT Typical Application Schematic for Two Channel Operation  2001 Semtech Corp. 6 www.semtech.com SC2450 POWER MANAGEMENT Typical Application (Cont.) Bill of Material for Two Channel Operation Item 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Qty Reference 8 3 2 1 2 1 6 2 2 3 1 11 4 4 2 2 C1 - C8 C9,C24,C25 C10,C11 C12 C13,C14 C15 C16,C19,C20,C21,C22,C23 C17,C18 C26,C27 C28,C29,C50 C30 C31,C32,C33,C36,C37,C40,C41,C42,C43,C44,C45 C34,C35,C38,C39 D1,D2,D5,D6 D3,D4 L1,L2 Part Number/Value 0.47µF, 50V, Cer. 0.33µF, Cer., 1206 22nF, Cer., 1206 0.1µF, Cer., 1206 10nF, Cer., 1206 47pF, Cer., 1206 22µF, 35V, Tant. 680µF, 35V, Alum. 2.2nF, Cer., 1206 1.0nF, Cer., 1206 1.0µF, Cer., 1206 10µF, Cer., 1206 1500µF, 6.3V, Alum. 1A, 40V, Schottky, MELF, 1N5819M 3A, 40V, Schottky, 30BQ040 Inductor, 9 turns Manufacturer Any Any Any Any Any Any Any Any Any Any Any Any Any Any Any Magnetics: Kool Mu P/N: 77206-A7 Fairchild P/N: FDB7030BL BCP56CT Any Any Any Any Any Any 17 18 19 20 21 22 23 24 4 1 2 2 4 1 2 1 M1,M2,M3,M4 Q1 R1,R3 R4,R6 R2,R5,R7,R11 R8 R9,R10 R12 N-Channel MOSFET, TO263AB 80V, 1A, NPN, Med. Pwr. SOT-223 2.2, 5%, 1206 4.7, 5%, 1206 1.0, 5%, 1206 56k, 5%, 1206 2.2k, 5%, 1206 Chip resistor, 0.005, 1W, 1%, 2512  2001 Semtech Corp. 7 www.semtech.com SC2450 POWER MANAGEMENT Typical Application (Cont.) Bill of Material for Two Channel Operation (Cont.) Item 25 26 27 28 29 30 31 32 33 34 35 36 37 Qty Reference 4 1 2 1 1 2 1 1 1 1 1 0 1 R13,R14,R15,R16 R17*,R19,R31* R20,R21 R22 R23 R26,R27 R28 R29 R34 R36 R37 Roc1*,Roc2* SC2450 Part Number/Value 2.2, 1/4W, 5%, 1210 Chip resistor, 0, 1206 1.00k, 1%, 1206 2.32k, 1%, 1206 4.02k, 1%, 1206 20, 5%, 1206 10, 5%, 1206 51, 5%, 1206 15k, 5%, 1206 68.1k, 1%, 1206 10.0k, 1%, 1206 TBD, 1%, 1206 Bi-Phase/Dual Controller, SO-28W Manufacturer Any Any Any Any Any Any Any Any Any Any Any Any Semtech Corp. P/N: SC2450ISW 805-498-2111 Notes: 1. * Indicates optional parts. 2. Some parts are selected due to availability or lead time, and are not optimized.  2001 Semtech Corp. 8 www.semtech.com SC2450 POWER MANAGEMENT Typical Application (Cont.) Schematic for Bi-Phase Operation  2001 Semtech Corp. 9 www.semtech.com SC2450 POWER MANAGEMENT Electrical Characteristic Curves Two Channel Operation Efficiency in Two-Channel Application Circuit (5V/12A, 3.3V/18A) Overall System Efficiency vs. Overall Load (W ) of the 5V and 3.3V channels 95.00% 90.00% 85.00% Efficiency 80.00% Efficiency 75.00% 70.00% 65.00% 60.00% 0 20 40 60 Output Power (W ) 80 100 120 Phase Node Waveform of Two-Channel Application Circuit (Vin = 24V, Load Current = 12A for 5V, Load Current = 18A for 3.3V) ch1: Vphase5V; ch2: Vphase3.3V  2001 Semtech Corp. 10 www.semtech.com SC2450 POWER MANAGEMENT Electrical Characteristic Curves (Cont.) 3.3V Channel Gate Waveform (Vin = 24V, Load Current = 18A) ch1: VgateH; ch2: VgateL 5.0V Channel Gate Waveform (Vin = 24V, Load Current = 12A) ch1: VgateH; ch2: VgateL  2001 Semtech Corp. 11 www.semtech.com SC2450 POWER MANAGEMENT Electrical Characteristic Curves (Cont.) Start-up (Vin = 24V, Vout1 = 5.0V/12A, Vout2 = 3.3V /18A) ch1: Vout5.0V; ch2: Vout3.3V Bi-Phase Operation (Vout = 3.3V, Max. Load Current = 20A) Efficiency in Bi-Phase Application Circuit (3.3V/20A) Overall System Efficiency vs. iLoad 90.00% 85.00% 80.00% Efficiency 75.00% Overall Efficiency 70.00% 65.00% 60.00% 0 5 10 Load Current (A) 15 20  2001 Semtech Corp. 12 www.semtech.com SC2450 POWER MANAGEMENT Electrical Characteristic Curves (Cont.) Phase Node Waveform (Vin = 24V, Vout = 3.3V, Load Current = 20A) ch1: Vphase1; ch2: Vphase2 Gate Waveform (Vin = 24V, Vout = 3.3V, Load Current = 10A/phase) ch1: VgateL; ch2: VgateH  2001 Semtech Corp. 13 www.semtech.com SC2450 POWER MANAGEMENT Electrical Characteristic Curves (Cont.) Start-up (Vin = 24V, Vout = 3.3V, Load Current = 5A/phase) ch1: Vout Theory of Operation The SC2450 employs a voltage mode control with feed forward to provide fast output response to load and line transients. The SC2450 has two outputs, which can be used to generate two separate supply voltages or can be combined in bi-phase operation to generate one single supply voltage. The internal reference is trimmed to 1 V with +/-1% accuracy, and the outputs voltages can be adjusted by two external resistors. In biphase operation, the dual switching regulators are operated 180° out of phase. Load current sharing between phases is normally required, and this can be achieved by using precise feedback voltage divider resistors (typically 0.1%) to match individual phase output voltage. In addition, small drooping resistors ( could be PCB