SEMTECH SC1102

SC1102/SC1102A Synchronous Voltage Mode Controller for Distributed Power Supply Applications POWER MANAGEMENT Features Description The SC1102 and SC1102A are low-cost, full featured, ‹ 1.265V reference available synchronous voltage-mode controllers designed for use ‹ Synchronous operation for high efficiency (95%) in single ended power supply applications where efficiency ‹ R current sensing DS(ON) is of primary concern. Synchronous operation allows for ‹ On-chip power good and OVP functions the elimination of heat sinks in many applications. The ‹ Small size with minimum external components SC1102s are ideal for implementing DC/DC converters ‹ Soft Start needed to power advanced microprocessors in low cost ‹ Enable function systems, or in distributed power applications where effi- ‹ 14 Pin SOIC lead free package available. Fully ciency is important. Internal level-shift, high-side drive WEEE and RoHS compliant circuitry, and preset shoot-thru control, allows the use of inexpensive N-channel power switches. Applications ‹ Microprocessor core supply SC1102s features include temperature compensated ‹ Low cost synchronous applications voltage reference, triangle wave oscillator and current ‹ Voltage Regulator Modules (VRM) sense comparator circuitry. Power good signaling, shut- ‹ DDR termination supplies down, and over voltage protection are also provided. ‹ Networking power supplies The SC1102 operates at a fixed frequency of 200kHz ‹ Sequenced power supplies and the SC1102A at 500kHz, providing a choice for op- timum compromise between efficiency, external compo- nent size, and cost. Two SC1102s can be used together to sequence power up of telecom systems. The power good of the first SC1102 connected to the enable of the second SC1102 makes this possible. Typical Application Circuit T T T T Typical Distribut ypical Distribut ypical Distribut ypical Distribut ypical Distributed P ed P ed P ed P ed Po o o o ow w w w wer Supply er Supply er Supply er Supply er Supply +5V + R4 C6 C5 C7 C8 Vin 5V R1 R2 10 U1 C1 10.0 680/6.3V 680/6.3V 680/6.3V 1k SC1102 opt. C2 0.1 _ 1 14 VCC GND PWRGD C3 0.1 2 13 PWRGD SS/SHDN SHDN R3 0.1 1k 3 12 OVP OVP VREF VREF R8 124* 4 11 OCSET SENSE R7 127 5 10 +12V PHASE BSTH C4 D1 1.0 Q1 L1 MBR0520 6 9 STP40NE 2uH DRVH BSTL + R5 Q2 3.9 7 8 STP40NE PGND DRVL C9 C10 C11 C12 C13 Vout=2.5V* 180/4V 180/4V 180/4V 180/4V 180/4V R6 2.2 _ NOTE: *) Vout = 1.265 x (1+R8/R7) Figure 1. 1 Revision: January 5, 2006 www.semtech.com SC1102/SC1102A 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. Exposure to Absolute Maximum rated conditions for extended periods of time may affect device reliability. Pl arameter Sm ymbo Ms aximu Unit VV CC, BSTL to GND -V 1.0 to 14 IN PGND to GND ±V 0.5 (1) PHASE to GND -V 0.5 to 18 BSTH to PHASE 1V 4 Thermal Resistance Junction to Case 4W 5 °C/ θ JC Thermal Resistance Junction to Ambient θ 1W 15 °C/ JA OT perating Temperature Range 0C to 70 ° A MT aximum Junction Temperature 1C 25 ° J ST torage Temperature Range -C 65 to +150 ° STG LT ead Temperature (Soldering) 10 Sec. 3C 00 ° LEAD Note: (1) -1.5V to 20V for 25ns repetitive every cycle. Electrical Characteristics o Unless specified: V = 4.75V to 12.6V; GND = PGND = 0V; FB = V ; V = 12V; V = 12V; T = 25 C CC O BSTL BSTH-PHASE J Ps arameter Cn ondition Mp i Tx y Ms a Unit Power Supply SC upply Voltage V2 C 46 . 1V 2. SC upply Current E6 N = VC 1A0 m LV ine Regulation V5 O = 2.5 0% . Error Amplifier Gain (AOL) 3B 5 d Input Bias 58 µA Oscillator O2 scillator Frequency S0 C110 10 7 20 0 2z 3 kH S5 C1102A 40 2 55 0 57 O0 scillator Max Duty Cycle 959% MOSFET Drivers D, H Source/Sink BSTH - DH = 4.5V1A DH- PHASE = 2V D. L Source/Sink BSTL - DL = 4.5V1A DL - PGND. = 2V www.semtech.com  2006 Semtech Corp. 2 SC1102/SC1102A POWER MANAGEMENT Electrical Characteristics (Cont.) o Unless specified: V = 4.75V to 12.6V; GND = PGND = 0V; FB = V ; V = 12V; V = 12V; T = 25 C CC O BSTL BSTH-PHASE J Ps arameter Cn ondition Mp i Tx y Ms a Unit PROTECTION OVP Threshold Voltage 2% 0 OV VP Source Current =0 3V1A m OVP P8 ower Good Threshold 821% 1 D5 ead Time 401s 0 n OV ver current Set Isink 2.0 ≤ V ≤10 2V10 8 20 0 2A 2 µ OCSET Reference RC eference Voltage 02 °C to 70° 15 .25 18 .26 1V .27 A1 ccuracy -1+% Soft Start CV harge Current =0 1.5V 80 . 121A µ SS DV ischarge Current =5 1.5V 1A . µ SS NOTES: (1) Specification refers to application circuit (Figure 1). (2) This device is ESD sensitive. Use of standard ESD handling precautions is required.  2006 Semtech Corp. 3 www.semtech.com SC1102/SC1102A POWER MANAGEMENT Pin Configuration Ordering Information (1) DeviceFe requency Packag Top View SC1102CS.TR 200kHz (2) SC1102CSTRT SO-14 SC1102ASTR 500kHz (2) SC1102ASTRT Sd C1102EVB Evaluation Boar Notes: (1) Only available in tape and reel packaging. A reel contains 2500 devices. (14-Pin SOIC) (2) Lead free product. This product is fully WEEE and RoHS compliant. Pin Descriptions Pe in #Pn in Nam Pin Functio 1CVe C Chip supply voltag 2DPe WRG Logic high indicates correct output voltag 3PO. V Over voltage protection 4TOt CSE Sets the converter overcurrent trip poin 5E PHAS Input from the phase node between the MOSFET’S 6HDt High side driver outpu 7DPd GN Power groun 8LDt Low side driver outpu 9LB. ST Bootstrap, low side driver 1H 0B. ST Bootstrap, high side driver 1E 1St ENS Voltage sense inpu 1F 2V. RE Buffered band gap voltage reference 1N 3 SS/SHD Soft start. A capacitor to ground sets the slow start time. 1D 4Gd N Signal groun NOTE: (1) All logic level inputs and outputs are open collector TTL compatible. www.semtech.com  2006 Semtech Corp. 4 SC1102/SC1102A POWER MANAGEMENT Block Diagram Applications Information - Theory of Operation low, turning off the high-side FET, and DL is pulled high, Synchronous Buck Converter Primary V power is provided by a synchronous, volt- turning on the low-side FET (once the cross-current con- CORE age-mode pulse width modulated (PWM) controller. This trol allows it). section has all the features required to build a high effi- As SENSE increases, the output voltage of the error ciency synchronous buck converter, including “Power amplifier decreases. This causes a reduction in the on- Good” flag, shut-down, and cycle-by-cycle current limit. time of the high-side MOSFET connected to DH, hence The output voltage of the synchronous converter is set lowering the output voltage. and controlled by the output of the error amplifier. The Under Voltage Lockout external resistive divider reference voltage is derived from The under voltage lockout circuit of the SC1102 assures an internal trimmed-bandgap voltage reference (See Fig. that the high-side MOSFET driver outputs remain in the 1). The inverting input of the error amplifier receives its off state whenever the supply voltage drops below set parameters. Lockout occurs if V falls below 4.1V. Nor- voltage from the SENSE pin. CC mal operation resumes once V rises above 4.2V. CC The internal oscillator uses an on-chip capacitor and trimmed precision current sources to set the oscillation Over-Voltage Protection frequency to 200kHz/500kHz. The triangular output of The over-voltage protection pin (OVP) is high only when the voltage at SENSE is 20% higher than the target value the oscillator sets the reference voltage at the inverting programmed by the external resistor divider. The OVP pin input of the comparator. The non-inverting input of the is internally connected to a PNP’s collector. comparator receives it’s input voltage from the error am- plifier. When the oscillator output voltage drops below the error amplifier output voltage, the comparator out- Power Good The power good function is to confirm that the regulator put goes high. This pulls DL low, turning off the low-side outputs are within +/-10% of the programmed level. FET, and DH is pulled high, turning on the high-side FET PWRGD remains high as long as this condition is met. (once the cross-current control allows it). When the oscil- lator voltage rises back above the error amplifier output PWRGD is connected to an internal open collector NPN voltage, the comparator output goes low. This pulls DH transistor.  2006 Semtech Corp. 5 www.semtech.com SC1102/SC1102A POWER MANAGEMENT Applications Information (Cont.) Soft Start Initially, SS/SHDN sources 10µA of current to charge an An over-current condition occurs when the high-side drive external capacitor. The outputs of the error amplifiers is turned on, but the PHASE node does not reach the are clamped to a voltage proportional to the voltage on voltage level set at the OCSET pin. The PHASE node is SS/SHDN. This limits the on-time of the high-side sampled only once per cycle during the valley of the tri- MOSFETs, thus leading to a controlled ramp-up of the angular oscillator. Once an over-current occurs, the high- output voltages. side drive is turned off and the low-side drive turns on and the SS/SHDN pin begins to sink 2uA. The soft-start R Current Limiting voltage will begin to decrease as the 2uA of current dis- DS(ON) The current limit threshold is set by connecting an exter- charges the external capacitor. When the soft-start volt- nal resistor from the V supply to OCSET. The voltage age reaches 0.8V, the SS/SHDN pin will begin to source CC drop across this resistor is due to the 200µA internal 10uA and begin to charge the external capacitor causing sink sets the voltage at the pin. This voltage is compared the soft-start voltage to rise again. Again, when the soft- to the voltage at the PHASE node. This comparison is start voltage reaches the level of the internal oscillator, made only when the high-side drive is high to avoid false switching will occur. current limit triggering due to uncontributing measure- ments from the MOSFETs off-voltage. When the voltage If the over-current condition is no longer present, normal at PHASE is less than the voltage at OCSET, an overcurrent operation will continue. If the over-current condition is condition occurs and the soft start cycle is initiated. The still present, the SS/SHDN pin will again begin to sink synchronous switch turns off and SS/SHDN starts to 2uA. This cycle will continue indefinitely until the over- sink 2µA. When SS/SHDN reaches 0.8V, it then starts current condition is removed. to source 10µA and a new cycle begins. In conclusion, below is shown a typical “12V Application Hiccup Mode Circuit” which has a BSTH voltage derived by bootstrapping During power up, the SS/SHDN pin is internally pulled input voltage to the PHASE node through diode D1. This low until VCC reaches the undervoltage lockout level of circuit is very useful in cases where only input power of 4.2V. Once V has reached 4.2V, the SS/SHDN pin is 12V is available. CC released and begins to source 10µA of current to the external soft-start capacitor. As the soft-start voltage In order to prevent substrate glitching, a small-signal di- rises, the output of the internal error amplifier is clamped ode should be placed in close proximity to the chip with to this voltage. When the error signal reaches the level cathode connected to PHASE and anode connected to of the internal triangular oscillator, which swings from 1V PGND. to 2V at a fixed frequency of 200kHz/500kHz, switching occurs. As the error signal crosses over the oscillator signal, the duty cycle of the PWM signal continues to in- crease 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. www.semtech.com  2006 Semtech Corp. 6 SC1102/SC1102A POWER MANAGEMENT Application Circuit Typical 12V Application Circuit with Bootstrapped BSTH +5V + R4 C5 C6 C7 C8 Vin 12V R1 R2 10 U1 C1 10.0 270/16V 270/16V 270/16V 1k 1.74k C2 SC1102 opt. D2 0.1 MBRA130 _ 1 14 VCC GND PWRGD C3 SHDN 0.1 2 13 PWRGD SS/SHDN R3 VREF 1k 3 12 OVP OVP VREF R9 205* 4 11 OCSET SENSE R8 127 5 10 PHASE BSTH D1 C9 L1 Q1 C4 MBR0520 1.0 STP40NE 4uH 6 9 DRVH BSTL 1.0 + R5 Q2 3.9 7 8 STP40NE PGND DRVL D3 C10 C11 C12 C13 C14 MBRD1035 Vout=3.3V* 180/4V 180/4V 180/4V 180/4V 180/4V R6 Optional 2.2 _ NOTE: *) Vout = 1.265 x (1+R9/R8)  2006 Semtech Corp. 7 www.semtech.com SC1102/SC1102A POWER MANAGEMENT Typical Characteristics Wave forms are shown for SC1102 and are similiar for SC1102A but at a higher frequency. Output Ripple Voltage Ch1: Vo_rpl Gate Drive Waveforms Ch1: Top FET 1. V = 5V; V = 3.3V; I = 12A IN O OUT Ch2: Bottom FET PIN Descriptions Ch1: Vo_rpl Ch1: Top FET 2. V = 5V; V = 1.3V; I = 12A IN OUT OUT Ch2: Bottom FET www.semtech.com  2006 Semtech Corp. 8 SC1102/SC1102A POWER MANAGEMENT Typical Characteristics (Cont.) Ch1: Vo_rpl Ch1: Top FET 2. V = 5V; V = 1.3V; I = 12A Ch2: Bottom FET IN OUT OUT Error Amplifier, Gain and Phase 40 180 35 PIN Descriptions 30 135 25 20 90 15 Gain 10 45 Phase 5 0 0 -5 -10 -45 100.0E+0 1.0E+3 10.0E+3 100.0E+3 1.0E+6 10.0E+6 Frequency (Hz)  2006 Semtech Corp. 9 www.semtech.com Gain (dB) Phase (deg) SC1102/SC1102A POWER MANAGEMENT Typical Characteristics (Cont.) Hiccup Mode Ch1: Vin Ch2: Vss Ch3: Top Gate Ch4: Vout Vin = 5V Vout = 3.3V Vbst = 12V Iout = S.C. Iout = S.C. Iout = S.C. Iout = S.C. Iout = S.C. Start Up Mode Ch1: Vin Ch2: Vss Ch3: Top Gate Ch4: Vout Vin = 5V Vout = 3.3V Iout = 2A Vbst = 12V www.semtech.com  2006 Semtech Corp. 10 SC1102/SC1102A POWER MANAGEMENT Evaluation Board Schematic  2006 Semtech Corp. 11 www.semtech.com C27 Q4 L1 R8 +5V Vbias D1 + D2 C9 C10 R4 C5 C6 C7 C8 Vin R1 R2 U1 C2 C28 C3 _ 1 14 VCC GND D5 R7 R5 PWRGD C4 2 13 SHDN PWRGD SS/SHDN C1 C15 C13 R3 R10 12 3 VREF OVP OVP VREF R14 4 11 OCSET SENSE R12 R13 10 5 R11 PHASE BSTH C26 Q1 R16 C18 L2 6 9 DRVH BSTL D3 + C23 C24 Q2 R17 7 8 R19 PGND DRVL D4 C20 C21 C22 C25 Vout R18 C19 Q3 _ C16 R15 C17 SC1102/SC1102A POWER MANAGEMENT Outline Drawing - S0IC - 14 DIMENSIONS INCHES MILLIMETERS A DIM MIN NOM MAX MIN NOM MAX D e - - A .053 .069 1.35 1.75 N - - A1 .004 .010 0.10 0.25 - - A2 .049 .065 1.25 1.65 2X E/2 - - b .012 .020 0.31 0.51 c - - .007 .010 0.17 0.25 E D .337 .341 .344 8.55 8.65 8.75 E1 .150 .154 .157 3.80 3.90 4.00 E1 E .236 BSC 6.00 BSC e .050 BSC 1.27 BSC - - h .010 .020 0.25 0.50 ccc C 12 3 L .016 .028 .041 0.40 0.72 1.04 B (.041) (1.04) 2X N/2 TIPS L1 N 14 14 - - 01 0° 8° 0° 8° aaa .004 0.10 .010 0.25 bbb D ccc .008 0.20 aaa C h A2 A SEATING PLANE C h A1 H bxN bbb C A-B D c GAGE PLANE 0.25 L 01 (L1) A SEE DETAIL SIDE VIEW DETAIL A NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. DATUMS AND TO BE DETERMINED AT DATUM PLANE -A- -B- -H- 3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. 4. REFERENCE JEDEC STD MS-012, VARIATION AB. Land Pattern - SOIC - 14 X DIMENSIONS DIM INCHES MILLIMETERS C (.205) (5.20) G .118 3.00 (C) G Z P .050 1.27 X .024 0.60 Y .087 2.20 Y Z .291 7.40 P NOTES: 1. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. 2. REFERENCE IPC-SM-782A, RLP NO. 302A. Contact Information Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805)498-2111 FAX (805)498-3804 www.semtech.com  2006 Semtech Corp. 12