SEMTECH SC1104B

SC1104A/B Simple, Synchronous Voltage Mode PWM Controller POWER MANAGEMENT Features Description The SC1104A/B is a versatile voltage-mode PWM con- ‹ Up to +14V input, 300kHz operation (SC1104A) troller designed for use in single ended DC/DC power ‹ Up to +7V input, 600kHz operation (SC1104B) supply applications. A simple, fixed frequency high effi- ‹ High efficiency (>90%) ciency buck regulator can be implemented using the ‹ 1% Reference voltage accuracy SC1104A/B with a minimum of external components. ‹ Hiccup mode over current protection Internal level shift and drive circuitry eliminates the need ‹ Robust output drive for an expensive P-channel, high-side switch. The small ‹ R Current sensing DS(ON) device footprint allows for compact circuit design. ‹ Industrial temperature range ‹ 8-Lead SOIC package. Pb-free package available, SC1104A/B features include temperature compensated fully WEEE and RoHS compliant voltage reference, triangle wave oscillator, current limit comparator and an externally compensated error ampli- fier. Current limit is implemented by sensing the voltage Applications drop across the top FET’s R . DS(ON) ‹ Termination supplies ‹ Low cost microprocessor supplies The SC1104 operates at fixed frequencies of ‹ Peripheral card supplies 300kHz(A) or 600kHz(B) providing an optimum com- promise between efficiency, external component size, ‹ Industrial power supplies and cost. 600kHz switching frequency is reserved for ‹ High density DC/DC conversion the SC1104B, +5V operation only. CC SC1104A/B has a thermal protection circuit, which is activated if the junction temperature exceeds 150°C. Typical Application Circuit Typical Distributed Power Supply + C3 1 C1 C4 C5 C6 C7 Vin 5 to 12V D1 510-1500pF 47/16V 10.0 47/16V 47/16V MBRA130L U1 _ SC1104A/B C2 R1 R4 200-2k 0.01 2.32k 1 8 COMP/SS SENSE R3 1.00k 2 7 GND VCC R5 C8 200-1k 0.1-0.33 3 6 DL PHASE 4 5 DH BST R8 opt C9 Q1 0.1 R6 L1 Si4884DY 1-5.1 1.5-6.8uH + Q2 R7 1-5.1 Si4874DY D2 C10 C11 C12 C13 C14-17 3.3V (opt) 220/4V 220/4V 220/4V 220/4V 1.0 _ Figure 1 1 Revision: November 22, 2006 www.semtech.com SC1104A/B 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 V to GND +V 20 CC BST to PHASE +V 20 PHASE to GND -V 0.5 to +20 COMP/SS to GND +V 7 SENSE to GND +V 7 Thermal Resistance Junction to Case 4W 0 °C/ θ JC Thermal Resistance Junction to Ambient θ 1W 60 °C/ JA OT perating Junction Temperature Range -C 40 to +125 ° J OT perating Ambient Temperature Range -C 40 to +85 ° A ST torage Temperature Range -C 65 to +150 ° STG LT ead Temperature (Soldering) 10 Sec. 3C 00 ° Lead EV SD Rating (Human Body Model) 2V k ESD Electrical Characteristics o o Unless specified: A: V = 12 ± 0.6V, V = 23 ± 1V, V = 3.3V, T = T = 25 C. B: V = 5 ± 0.25V, V = 12 ± 0.6V, V = 2.0V, T = T = 25 C CC BST OUT J A CC BST OUT J A Pl arameterSs ymbo Cn ondition Mp i Tx y Ms a Unit Power Supply SV upply Voltage F=5 300kHz (nom.), SC1104A44 . 1V CC SW V F=5 600kHz (nom.), SC1104B47 . CC SW SI upply Current V ≤01 .4V 141A m CC COMP Error Amplifier (1) E/A Transconductance g 1S 2 m m (1) Open Loop DC Gain A 4B 2 d O (1) Bandwidth - 3dB F 4z 00 kH BW II nput Bias Current 13 µA FB Output Sink Current I V ≥ 1.1V; V=5 1.5V 07 .6 0. SIK SENSE COMP mA I V ≥ 0.9V; V=5 1.5V 01 .9 1. Source Current SC SENSE COMP Oscillator SF witching Frequency V=5 12V ± 0.6V 20 5 35 0 34 OSC CC kHz V=0 5V ± 0.25V 50 1 60 0 69 CC www.semtech.com 2 © 2006 Semtech Corp. SC1104A/B POWER MANAGEMENT Electrical Characteristics o o Unless specified: A: V = 12 ± 0.6V, V = 23 ± 1V, V = 3.3V, T = T = 25 C. B: V = 5 ± 0.25V, V = 12 ± 0.6V, V = 2.0V, T = T = 25 C CC BST OUT J A CC BST OUT J A Pl arameter Ss ymbo Cn ondition Mp i Tx y Ms a Unit (1) Ramp Peak Voltage V 4.75V ≤ V ≤10 2.6V 2V . P-K CC (1) Ramp Valley Voltage V 4.75V ≤ V ≤10 2.6V 1V . V CC (2) Maximum Duty Cycle dc V=0 12V (300kHz, SC1104A) 959% MAX CC V=5 5V (600kHz, SC1104B) 80 9 CC MOSFET Drivers DH Sink/Source Current I d.c. < 2%, t < 100µs 08 .60A . DH PW SC1104A V = 4.5V (src) GS DL Sink/Source Current I 07 .6 0. DL V = 2.5V (snk) GS SC1104A DH Sink/Source Current I d.c. < 2%, t < 100µs 06 .450A . DH PW SC1104B V = 4.5V (src) GS DL Sink/Source Current I 06 .45 0. DL V = 2.5V (snk) GS SC1104B Df H Rise/Fall Time tC r, t=0 3000pF, See Fig. 2 5s n L Df L Rise/Fall Time tC r, t=0 4000pF, See Fig. 2 5 L Dt ead Time S0 ee Fig. 2 8s n dt Dt H Minimum Off Time 4.75V ≤ Vcc ≤10 2.6V 16 OFF Reference Section RV eference Voltage 4.75V ≤ Vcc ≤10 2.6V 00 .9910 .00 1V .01 REF Temp Variance 0 < T<1 +70°C -1% ΔV J REF -40 < T<5 +85°C -5 1. 1. J LT ong Term Stability =5 125°C, 1000 hrs. mV J Current Limit TV rip Voltage 4< .75V V< cc 12.6V 10 8020 0 2V 2 m TRIP V = Vcc - V trp PHASE Soft-Start/Enable SI S Source Current V<5 2.5V 08 . 1A . µ SRC COMP SI S Sink Current V>5 0.5V 08 . 1A . µ SNK COMP Enable Input Threshold 15 .00 1V .3 EV nable Input Current =2 0.8V mA COMP 3 www.semtech.com © 2006 Semtech Corp. SC1104A/B POWER MANAGEMENT Electrical Characteristics o o Unless specified: A: V = 12 ± 0.6V, V = 23 ± 1V, V = 3.3V, T = T = 25 C. B: V = 5 ± 0.25V, V = 12 ± 0.6V, V = 2.0V, T = T = 25 C CC BST OUT J A CC BST OUT J A Pl arameter Ss ymbo Cn ondition Mp i Tx y Ms a Unit Under Voltage Lockout UV VLO Threshold -40 < T<9 85°C 35 . 45 .1 4V . th J Thermal Shutdown (2) Over Temperature Trip Point T 10 40 1C 6 ° OTP Notes: (1) Guaranteed by design. (2) Not tested, by characterization. Figure 2 Block Diagram Figure 3 www.semtech.com 4 © 2006 Semtech Corp. SC1104A/B POWER MANAGEMENT Pin Configuration Ordering Information (2) DevicePT ackage Temp Range ( ) J Top View (1) SC1104XISTR SC OIC-8 -40° to 125° (1)(3) SC1104XISTRT Sd C1104XEVB Evaluation Boar Notes: (1) In place of “X”: A = 300kHz, V = 5V to 12V. CC B = 600kHz, V = 5V. CC (2) Only available in tape and reel packaging. A reel (8-Pin SOIC) contains 2500 devices. (3) Lead free product. This product is fully WEEE and RoHS compliant. Pin Descriptions Pin Pn in Name Pin Functio # 1SC. OMP/S Error amplifier output. Compensation, soft start/enable 2DG. N Ground 3LDt Low side driver outpu 4HDt High side driver outpu 5TB. S Bootstrap, high side driver 6EP. HAS Input from the phase node between the MOSFETs 7CV. C Chip bias supply voltage 8ES. ENS Output voltage sense input Marking Information yyww = Date Code (Example: 0012) xxxxxxxx = Semtech Lot No. (Example: E90101-1) 5 www.semtech.com © 2006 Semtech Corp. SC1104A/B POWER MANAGEMENT Theory of Operation Synchronous Buck Converter The output voltage of the synchronous converter is set The circuit will be in steady state when Vout =3.3V , and controlled by the output of the error amplifier. The Vsense = 1V, Icomp = 0 . The COMP voltage and duty inverting input of the error amplifier receives its voltage cycle depend on Vin. from the SENSE pin. The non-inverting input of the error amplifier is connected to an internal 1V reference. Under Voltage Lockout The error amplifier output is connected to the The under voltage lockout circuit of the SC1104A/B as- COMPensation pin. The error amplifier generates a cur- sures that both high-side and low-side MOSFET driver rent proportional to (Vsense – 1V), which is the COMP outputs remain in the off state whenever the supply volt- pin output current (Transconductance ~ 12mS). The age drops below set parameters. Lockout occurs if V CC voltage on the COMP pin is the integral of the error am- falls below 4.2V typ. plifier current. The COMP voltage is the non-inverting input to the PWM comparator and controls the duty cycle R Current Limiting DS(ON) of the MOSFET drivers. The size of capacitor Ccomp con- trols the stability and transient response of the regula- In case of a short circuit or overload, the high-side (HS) tor. The larger the capacitor, the slower the COMP volt- FET will conduct large currents. To prevent damage, in age changes, and the slower the duty cycle changes. this situation, large currents will generate a fault condi- tion and begin a soft start cycle. The inverting input voltage of the PWM comparator is the triangular output of the oscillator. While the HS driver is on, the phase voltage is compared to the Vcc pin voltage. If the phase voltage is 200mV When the oscillator output voltage drops below the COMP lower than Vcc, a fault is latched and the soft start cycle voltage, the comparator output goes high. This pulls DL begins. low, turning off the low-side FET. After a short delay (“dead time”), DH is pulled high, turning on the high-side FET. The voltages are compared during the middle of the HS When the oscillator voltage rises back above the error pulse, to prevent transients from affecting the accuracy. amplifier output voltage, the comparator output goes low. This pulls DH low, turning off the high-side FET, and after The sampling of the voltage across the top FET occurs a dead time delay, DL is pulled high, turning on the low- after a time delay t = 100ns_typ from the time the DELAY side FET. The dead time delay is determined by a DH is pulled high. This delay prevents the measurement monostable on the chip. to be effected by ringing on the leading edge of the phase node pulse. The duration of the sampling is t = SAMPLE The triangle wave minimum is about 1V, and the maxi- 100ns_typ. It is being disabled at very low duty cycle when mum is about 2V. Thus, if Vcomp = 0.9V, high side duty t < 300ns_typ. This feature allows for the orderly start- ON cycle is the minimum (~0%) , but if Vcomp is 2.0V, duty up during the inrush of the current charging output ca- cycle is at maximum ( ~90%).The internal oscillator uses pacitor and the fault free operation with extremely high an on-chip capacitor and trimmed precision current input/output voltage ratio, e.g., V = 12V and V = 1V. IN OUT sources to set the oscillation frequency to 300kHz (SC1104A) or 600kHz (SC1104B). The over-current comparator (OC) is only active if the phase node is > 3.3V. This means that in the case of Figure 1 shows a 3.3V output converter. If the Vout <3.3V, power source being < 3V the OC will be disabled even then the SENSE voltage < 1V. In this case the error though the rest of the circuitry is completely functional. amplifier will be sourcing current into the COMP pin so SC1104 still can be used for stepping down, e.g. 2.8V to that COMP voltage and duty cycle will gradually increase. 2.5V, 2V, 1.8V, etc. If Vout > 3.3V, the error amplifier will sink current and reduce the COMP voltage, so that duty cycle will decrease. www.semtech.com 6 © 2006 Semtech Corp. SC1104A/B POWER MANAGEMENT Theory of Operation (Cont.) When choosing OC trip point one should consider the Closing the Loop Tempco of the MOSFETs Rds_on and SC1104’s Vtrip. Also, any ringing on the Vcc and Phase nodes due to In order to have a stable closed loop system with optimum parasitic L and C will have some effect on the OC Vtrip. transient response one should make sure that open-loop frequency response has an adequate Gain & Phase Example: margins. The Bode plot of log. Gain vs Freq. and Phase vs Freq. provide the necessary means for the circuit Iout_nom = 6A; assume I_max = 125% • Iout_nom = evaluation. Loop stability defined by compensation 7.5A networks around transconductance error amplifier (EA) and output divider, see below and output capacitor Cout and inductor Lout. Rds_on = 0.014Ω; assume Rds_on_max ≈ 150% • Rds_on = 0.02Ω Vout Cn Voc = 7.5A • 0.02Ω = 150mV. Ra Rn This proves that MOSFETs with R = 0.014Ω @ 25°C DS_ON EA is the right choice. _ Gm C + Soft Start C Cp Rb Vref R The soft start (or hiccup) circuitry is activated when a C fault occurs. Faults occur for three reasons: 1) Under voltage (V < 4.2V) CC 2) Over temperature (die temperature > 150°C) 3) Over current in high side FET. Typical transconductance error amplifier All faults are handled the same way. Both DH and DL are The inductor and output capacitor form a “double pole” forced low. The error amplifier is turned off, but a 2µA at the frequency: current flows into the comp pin (soft start current). The 1 f = sink current reduces the Comp voltage down to 0.6V LC 2 • • Lo • Co ∏ over a period of a few milliseconds. When Vcomp ~ 0.6V, the fault is cleared and the DL goes high. Also, the soft The ESR of the output capacitor and the output capacitor start current changes polarity and begins to increase the value create a “zero” at the frequency. voltage on the Comp capacitor. The DH remains low, be- cause Vcomp is less than the lowest excursion of the 1 f = ESR 2 • ∏ •ESR • Co oscillator ramp (1.0V). After a few ms, the Vcomp in- creases to about 1.0V and the DH will start to switch. The “zero” and “pole” from the EA compensation network The duty cycle will gradually increase, and Vsns will in- crease. When Vsns ~ 1.00V, the error amplifier turns on are: again. The circuit has now reached its operating point. If 1 1 f = f = Z P a fault occurs during the soft start, the cycle will begin 2 • •Rc • Cc 2 • •Rc • Cp ∏ ∏ again (drivers low, Vcomp decreasing down to 0.6V). The additional “lead” network R , C , R can be used to A N N improve phase margin in case when output capacitors with extra-low ESR are used and there is a need to compensate for “high quality” output Lo, Co filter. 7 www.semtech.com © 2006 Semtech Corp. SC1104A/B POWER MANAGEMENT Theory of Operation (Cont.) attenuation due to the L , C filter and the output 1 O O f = NET resistor divider R , R is compensated by the gain of 2 • • Ra • Cn ∏ A B the PWM modulator and the gain of the transconductance error amplifier (Gm • Z ). Value for the resistor R should be 1/10 of the output EA COMP N divider upper resistor R . A Shown below is a typical Bode plot of the open-loop frequency response of SC1104 based buck converter. Example. = 300kHz Switching frequency f SW Output capacitance C = 3 x 330µF OUT Output capacitor ESR = 45mΩ/each Output inductance L = 4.7µH OUT 80.0 -50.0 Input voltage V = 12V IN Output voltage V = 3.3V OUT 40.0 -150 Let’s choose crossover frequency f = 1/20 • f = 15kHz CO SW 0 -250 The compensation values used in this example are based on the following criteria: -40.0 -350 2 1 f = f ; f = 1/10 • f ; f = 10 • f = 150kHz Z LC NET LC P CO -80.0 -450 1 10 100 1k 10k 100k 1Meg Therefore, frequency in hertz 1 vdberr 2 vpherr 1 f = = 2.33kHz LC 2 • • 4.7µH• 990µF ∏ 1 f = = 10.72kHz ESR 2 • • 0.015 • 990µF ∏ Since, the EA can sink/source about 1mA, let’s choose Rc = 680Ω, then 1 C = = 0.1µF C 2 • • Fz • Rc ∏ 1 C = = 1500pF P 2 • • Fp •Rc ∏ Assuming the output divider lower resistor R = 1k, then B for V = 3.3V the R = 2.32k. OUT A 1 C = = 0.3µF N 2 • • f •Ra ∏ NET At the closed-loop crossover frequency f , the CO www.semtech.com 8 © 2006 Semtech Corp. Plot1 vdberr in db(volts) vpherr in degrees SC1104A/B POWER MANAGEMENT Typical Characteristics Reference Voltage vs. Temp Switching Frequency vs. Temp 0.5% 25% 0.4% 20% 0.3% 0.2% 15% 0.1% 10% 0.0% 5% -0.1% -0.2% 0% -0.3% -0.4% -5% -0.5% -10% -0.6% -0.7% -15% -0.8% -20% -0.9% -1.0% -25% -40 -20020 40 60 80 100 120 -40 -20 0 20406080 100 120 Temp, °C Temp, °C Trip Voltage vs. Temp Under Voltage Lockout vs. Temp 25% 10% 20% 8% 15% 6% 10% 4% 5% 2% 0% 0% -5% -2% -10% -4% -15% -6% -20% -8% -25% -10% -40 -20 0 204060 80 100 120 -40 -20 0 20406080 100 120 Temp, °C Temp, °C 9 www.semtech.com © 2006 Semtech Corp. Vtrip, % Vref, % UVLO, % Freq, % SC1104A/B POWER MANAGEMENT Evaluation Board Schematic - V = 5V IN 0 + C3 1.0 C8 C7 C9 C10 Vin=5V 47/6.3V 10.0 47/6.3V 47/6.3V C1 D1 1500p MBRA130L _ U1 SC1104AISTR C2 R1 R8 0.1 1k 1.50k 1 8 COMP/SS SENSE D2 2 7 GND VCC MBRA130L(opt) R9 R7 150 C11 1.0k 0.47 3 6 DL PHASE 4 5 DH BST C4 Q1 R5 0.1 R3 L1 Si4410DY 1 0 3.9uH + Q2 R4 2.2 Si4410DY C5 6800p C15 C16 C17 C18 330/4V 330/4V 330/4V 10 Vout=2.5@6A R6 2.2 _ Evaluation Board Schematic - V = 12V IN 0 + C3 1.0 C8 C7 C9 C10 Vin=12V 33/16V 10.0 33/16V 33/16V C1 D1 1500p LL4148 _ U1 SC1104AISTR C2 R1 R8 0.1 680 2.32k 1 8 COMP/SS SENSE D2 2 7 GND VCC MBRA130L(opt) R9 R7 220 C11 1.0k 0.33 3 6 DL PHASE 4 5 DH BST C4 Q1 R5 0.1 R3 L1 Si4410DY 2.2 5.1opt 4.7uH + Q2 R4 2.2 Si4410DY C5 3300p C15 C16 C17 C18 330/4V 330/4V 330/4V 10 Vout=3.3@6A R6 3.3 _ www.semtech.com 10 © 2006 Semtech Corp. SC1104A/B POWER MANAGEMENT Evaluation PC Board Top View Top Layer Bottom Layer 11 www.semtech.com © 2006 Semtech Corp. SC1104A/B POWER MANAGEMENT Typical Characteristics 100% 95% 90% 85% 12V = Vin 3.3V = Vout 80% 12A = Iout 75% 70% 65% 60% 02 4 6 8 10 12 Current, A 1.0% 0.8% 0.6% 0.4% 0.2% 0.0% -0.2% -0.4% -0.6% -0.8% -1.0% 02 468 10 12 Current, A www.semtech.com 12 © 2006 Semtech Corp. Regulation Efficiency SC1104A/B POWER MANAGEMENT Typical Characteristics (Cont.) 100% 95% 90% 5V = Vin 85% 2V = Vout 80% 12A = Iout 75% 70% 65% 60% 02 468 10 12 Current, A 1.0% 0.8% 0.6% 0.4% 0.2% 0.0% -0.2% -0.4% -0.6% -0.8% -1.0% 02 46 8 10 12 Current, A 13 www.semtech.com © 2006 Semtech Corp. Efficiency Regulation SC1104A/B POWER MANAGEMENT Outline Drawing - SOIC - 8 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 E1 D .189 .193 .197 4.80 4.90 5.00 E E1 .150 .154 .157 3.80 3.90 4.00 E .236 BSC 6.00 BSC e .050 BSC 1.27 BSC 12 - - h .010 .020 0.25 0.50 ccc C L .016 .028 .041 0.40 0.72 1.04 2X N/2 TIPS e/2 L1 (.041) (1.04) N 8 8 B - 8° 0° - 8° 01 0° aaa .004 0.10 bbb .010 0.25 D ccc .008 0.20 aaa C h A2 A SEATING PLANE h C A1 H bxN bbb C A-B D c GAGE PLANE 0.25 L 01 (L1) A SEE DETAIL DETAIL A SIDE VIEW 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 AA. Minimum Land Pattern - SOIC - 8 X DIMENSIONS DIM INCHES MILLIMETERS (.205) (5.20) C G .118 3.00 (C) G Z P .050 1.27 X .024 0.60 .087 2.20 Y 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. 300A. 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 14 © 2006 Semtech Corp.