SC4503 Semtech Corporation, SC4503 Datasheet
SC4503
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SC4503 Summary of contents
Page 1
... Boost and SEPIC. The SC4503 is available in low-profi le 5-lead TSOT-23 and 8-lead 2X2mm MLPD-W packages. The SC4503’s low shutdown current (< 1μA), high frequency operation and small size make it suitable for portable applications. ...
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... LEAD T IR ESD = T < 85° Conditions 2.5V < V < 20V 1. 2V 1.5V (not switching) SHDN/ SHDN/SS 2 SC4503 Maximum Units - +0 191* °C/W 78* °C/W 150 -65 to +150 °C 260 260 2000 V Min Typ Max Units 2 ...
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... Shutdown and Soft-start Pin. Pulling this pin below 0.4 shuts down the converter. Applying more than 2V at this pin enables the SC4503. An external resistor and an external capacitor con- nected to this pin soft-start the switching regulator. The SC4503 will try to pull the SHDN/SS pin 4 SHDN/SS below its 1 ...
Page 4
... Power Supply Pin. Bypassed with capacitor close to the pin. Shutdown and Soft-start Pin. Pulling this pin below 0.4 shuts down the converter. Apply- ing more than 2V at this pin enables the SC4503. An external resistor and an external capacitor connected to this pin soft-start the switching regulator. The SC4503 will try to pull the SHDN/SS pin below its 1 ...
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... SHDN/SS VOLTAGE 4 REFERENCE www.DataSheet4U.com 1.25V + 2007 Semtech Corp. REF NOT READY T > 155° ° ° ° C THERMAL J SHUTDOWN CLK - PWM + OSCILLATOR Figure 2. SC4503 Block Diagram 5 SC4503 I-LIMIT ILIM - + + Σ Σ Σ Σ ISEN - + ...
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... Switch Current 400 300 200 100 -40° 0.0 0.5 Switch Current (A) 2007 Semtech Corp 100 125 100 125 125° C 25° C 1.0 1.5 2.0 6 SC4503 Switching Frequency vs Temperature 1.5 1.4 1.3 1.2 1.1 1.0 -50 - 100 125 Temperature (° C) Switch Current Limit vs Temperature 2.0 1.8 1.6 1.4 1 SHDN/SS 1 ...
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... Shutdown Pin Voltage (V) 2007 Semtech Corp. -40° C 25° 1.5V FB 25° C -40° C 1.0 1.5 2.0 85° C 1.6 1.8 2.0 7 SC4503 Shutdown Pin Current vs Shutdown Pin Voltage 50 40 -40° C 25° 85° 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Shutdown Pin Voltage (V) Shutdown Pin Thresholds vs Temperature 1 ...
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... POWER MANAGEMENT Applications Information Operation The SC4503 is a 1.3MHz peak current-mode step-up switching regulator with an integrated 1.4A (minimum) power transistor. Referring to the block diagram, Figure 2, the clock CLK resets the latch and blanks the power transistor Q conduction edge of the clock. Switch current is sensed with an integrated sense resistor. ...
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... Figure 4. Current Waveforms in a Boost Converter Figure 4. Current Waveforms in a Boost Converter a boost converter therefore depends on the converter oper- ating duty cycle. The power switch current in the SC4503 is internally limited to at least 1.4A. This is also the maximum peak inductor or the peak input current. By estimating the ...
Page 10
... Measured minimum on time of the SC4503 is load-dependent and ranges from 180ns to 220ns at room temperature. The switch in the SC4503 is either not turned on, or, for at least this minimum. If the regulator requires a switch on-time less than this controllable minimum, then it will either skip cycles or start to jitter ...
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... Converter effi ciency will be improved if the voltage drop across the diode is lower. The rectifying diodes should be placed close to the SW pin of the SC4503 to minimize ringing due to trace induc- tance. Surface-mount equivalents of 1N5817 and 1N5818, MBRM120, MBR0520L, ZHCS400, 10BQ015 and equiva- lent are suitable ...
Page 12
... SS graph “Switch Current Limit vs. Shutdown Pin Voltage” in the “Typical Characteristics” shows that the voltage needs least 2V for the SC4503 to deliver its rated power. The effect of the SC4503 is analog between 1.4V and 2V. Within this range the switch current limit is determined not by ILIM but in- stead by the PWM signal path (see Figure 2) ...
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... In order for the SC4503 to achieve its rated switch current, must be greater than 2V in steady state. This puts an upper limit on R for a given enable voltage V SS voltage applied The maximum specifi ed ...
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... For jitter-free operation, the size of the loop formed by these components should be minimized. Since the power switch is integrated inside the SC4503, grounding the output fi lter capacitor next to the SC4503 ground pin minimizes size of the high di/dt current loop. The input bypass capacitors should also be placed close to the input pins ...
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... LED strings become open. 2007 Semtech Corp 10µH ZHCS400 + R3 24V 54. 4.7µ SC4503 4 3 SHDN/SS FB GND 22nF 56nF L1: Murata LQH32C C1: Murata GRM219R60J475K 15 D2 MM5Z24VT1 C2 C4 0.22µF 220pF R4 301k R1 R2 63.4 63.4 protects the converter 2 SC4503 www.semtech.com ...
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... C1: Murata GRM188R61A225K C2: Murata GRM21BR61C475K Figure 10(a). 3.3V to 12V Boost Converter with Soft-start V = 12V OUT 0.100 1.000 Upper Trace : Output Voltage, AC Coupled, 0.5V/div Lower Trace : Input Inductor Current, 0.5A/div Figure 10(c). 16 SC4503 VOUT 12V C4 R1 2.2pF 866k C2 4.7µF R2 100k 40µs/div Load Transient Response of the Circuit in Figure 10(a) ...
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... Efficiency vs Load Current 4. 3. OUT 55 1.3MHz 50 0.001 0.010 0.100 Load Current (A) Figure 11(b). Effi ciency of the Li-ion Cell to 5V Boost Converter V IN 40µs/div Load Transient Response. I between 0.15A and 0.9A SC4503 1.000 = 4.2V is switched OUT www.semtech.com ...
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... C2: Murata GRM21BR60J106K C5: Murata GRM188R61A225K Figure 12(a). Single Li-ion Cell to 3.3V SEPIC Converter 2. 3. 4.2V IN 0.100 1.000 Upper Trace : Output Voltage, AC Coupled, 0.2V/div Lower Trace : Input Inductor Current, 0.2A/div Figure 12(c). 18 SC4503 VOUT D1 3.3V, 0.45A 10BQ015 15pF 412k 3.3µH C2 10µF R2 249k V = 3.6V IN 40µs/div Load Transient Response of the Circuit in Figure 12(a) ...
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... Lower Trace : Inductor Current, 0.5A/div OUT2 26V (10mA 0.1µF 0.1µF 1µF D1 OUT1 9V (0.3A) 10BQ015 R1 309k C4 12pF C2 4.7µ 0.1µF 49.9k D7 OUT3 -8.5V (10mA) C10 D6 1µF 40µs/div Figure 13(c). Load Transient Response switched between 50mA and 350mA SC4503 OUT1 www.semtech.com ...
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... GND 6 GND VIN 5 FB SHDN/ SC4503_MLPD D1 SS13 N.P. 10uF 4.7uH 5VIN 10uF 47K OFF/ JP1 100nF L1 4.7uH 5VIN 5 SW VIN R3 C1 GND 47K 10uF OFF/ SHDN U1 SC4503 C5 JP1 100n SC4503 www.semtech.com ...
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... BSC 1.90 BSC L .012 .018 .024 0.30 0.45 0.60 (.024) (0.60 0° 8° 0° 8° aaa .004 0.10 bbb .008 0.20 ccc .010 0. GAGE PLANE 0. (L1) A DETAIL A -H- DIMENSIONS DIMENSIONS INCHES INCHES MILLIMETERS MILLIMETERS (.087) (2.20) .031 0.80 .037 0.95 .024 0.60 .055 1.40 .141 3.60 SC4503 www.semtech.com ...
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... NOM MAX MIN NOM MAX A .028 .031 0.70 0.75 0.80 .030 A1 .000 .001 .002 0.00 0.02 0.05 (.008) A2 (0.20) b .007 .010 .012 0.18 0.25 0.30 D .075 .079 .083 1.90 2.00 2.10 D1 .059 .063 .067 1.50 1.60 1.70 E .075 .079 .083 1.90 2.00 2.10 E1 .031 .035 .039 0.80 0.90 1.00 e .020 BSC 0.50 BSC L .008 .012 .016 0.20 0.40 0. aaa .003 0.08 bbb .003 0.08 SC4503 www.semtech.com ...