TS3404 PWM Buck Controller Pin assignment: 1. Out 2. Vcc 3. Comp. 4. FB 5. SCP 6. SS 7. CT 8. Gnd Supply Voltage Range 3.6V to 27V Output Driving Current 200mA Oscillator Frequency up to 300KHz General Description The TS3404 integrates Pulse Width Modulation (PWM) control circuit into a single chip, and makes simple work out of implementing a complete control and protection scheme for a DC-DC step-down converter. The TS3404 provides simple feedback loop compensation, 1.25V reference output, error amplifier, adjustable oscillator, soft start, under voltage lock out (UVLO), short circuit protection(SCP) circuitry, and push pull output circuit. The TS3404 is design for adjustable switching frequency by trimming time capacitor (CT), during low supply voltage situation, the under voltage lock out (UVLO) makes sure that the output are off until the internal circuit operates normally. The TS3404 is offered in DIP-8 and SOP-8 package. Features Pin Descriptions PWM buck control circuit Name Operating voltage can be up to 27V Output Under voltage lock out (UVLO) protection Soft start (SS) circuit Short circuit Protection (SCP) Variable oscillator frequency 300KHz (max) 1.25V voltage reference Output Vcc Comp. FB SCP Applications Description PWM Output Supply Voltage Feedback Loop Compensation Voltage Feedback Short Circuit Protection SS Soft Start CT Timing Capacitor Gnd Ground Ordering Information LCD Monitor xD-ROM, xDSL product DC to DC converters in computers TS3404CS Backlight inverter TS3404CD Part No. Operating Temp. (Ambient) o -20 ~ +85 C Package SOP-8 DIP-8 Absolute Maximum Rating Supply Voltage VCC 28 V Amplifier Input Voltage VI 20 V Collector Output Voltage VO Vcc~1.0V V ISOURCE 200 mA ISINK 200 mA TJ -20 ~ +150 o C -65 ~ +150 o C 260 o C Source Current Sink Current Operating Junction Temperature Range Storage Temperature Range TSTG Lead Temperature 1.6mm(1/16”) from case for 10Sec. TS3404 1-5 TLEAD 2003/12 rev. A Recommended Operating Conditions Parameter Symbol. Min. Max. Unit VCC 3.6 27 V Amplifier input voltage VI 1.05 1.45 V Collector output voltage VO Vcc~1.5 V Current into feedback terminal IFB 45 uA Feedback resistor RF 100 Timing capacitor CT 100 6800 pF FOSC 10 300 KHz Supply voltage Oscillator frequency KΩ Electrical Characteristics (VCC =6V, f = 200KHz, Ta =25 oC; unless otherwise specified.) Parameter Symbol Test Conditions Min Typ Max Unit 1.225 1.25 1.275 V - 0.1 1 % - 0.2 1 Reference Comp. Connect to FB Output voltage change with VREF o Ta= -20 C ~ 25 C o temperature o o Ta= 25 C ~ 85 C Under voltage lock out (UVLO) Upper threshold Voltage 2.9 VUT Lower threshold voltage VLWT Hysteresis VHT o IO(REF) = 0.1mA, Ta= 25 C V 2.4 0.5 Short circuit protection (SCP) Input threshold voltage o ViT Ta= 25 C 0.60 0.67 0.75 V Standby voltage VSTB No pull up 100 130 160 mV Latched input voltage VLT No pull up 50 100 mV - 15 - 20 uA Input (source) current ISCP Comparator threshold voltage VCT o VI = 0.7V, Ta= 25 C - 10 1.5 V Oscillator (OSC) Frequency Standard deviation of frequency FOSC CT = 270pF 200 KHz ∆FOSC CT = 270pF 10 % VCC = 3.6V ~ 20V 1 Frequency change with voltage Error Amplifier Input offset voltage VIO Input offset current IIO Input bias current IIB Common mode input voltage range Open loop voltage amplification Unity gain bandwidth Common mode reject ratio ±6 VO (FB)= 1.25V 160 VCM VCC = 3.6V ~ 20V AV RF = 200kΩ 1.05 70 GBW CMRR 60 Max. output voltage VOH VREF~0.1 Min. output voltage VOL Output (sink) current (Comp) IOI Output (source) current (Comp) IOO TS3404 ± 100 nA 500 nA 1.45 V 80 dB 1.5 MHz 80 dB V 1 VID = - 0.1V, VO = 1.25V 2-5 mV V 0.5 1.6 mA - 45 - 70 uA 2003/12 rev. A Electrical Characteristics (Continued) o (VCC =6V, f = 200KHz, Ta =25 C; unless otherwise specified.) Parameter Symbol Test Conditions Min Typ Max Unit Output section Leakage current Sink current Source current ILEAK IDRV VO = 25V 10 VIN = 20V 200 VIN= 20V 200 IO = 10mA 1.0 120 Output saturation voltage VSAT Short circuit output current ISC VO = 6V VTO CT uA mA mA 1.5 V mA PWM comparator Input threshold voltage at f =10KHz (Comp) VT100 Maximum duty cycle ICCA CT = 270pF 0.6 1.2 0.7 V 10 mA 1.3 Total device Average supply current 6 Soft Start Soft start voltage VSS 2.3 V Constant charge current ISS 20 uA Functional Block Diagram TS3404 3-5 2003/12 rev. A Typical Application Circuit Device Value Device Value C1 470uF R1 9K, 1/4W C2 10nF R2 3K, 1/4W C3 470uF R3 10K, 1/4W C4 50nF L1 33uH, 3A C5 270uF D1 SK34A C6 50nF Q1 TSM2301CX C7 220nF Remark: * Output = 1.25V * (R1/R2 +1) = 1.25V * (9K/3K + 1) = 5V @ 3A * SK34A: Taiwan semiconductor, Schottky 3A/40V in SMA package * TSM2301CX: Taiwan semiconductor, P-Channel MOSFET 4A/20V in SOT-23 package TS3404 4-5 2003/12 rev. A DIP-8 Mechanical Drawing A DIP-8 DIMENSION DIM 8 5 B 4 1 MILLIMETERS A MIN 9.07 MAX 0.32 MIN 0.357 MAX 0.367 B 6.22 6.48 0.245 0.255 C D 3.18 0.35 4.43 0.49 0.125 0.019 0.135 0.020 G L C J INCHES 2.54 (typ) 0.100 (typ) J K 0.29 3.25 0.31 3.35 0.011 0.128 0.012 0.132 L 7.75 8.00 0.305 0.315 M - 10 - 10 o o K M D G SOP-8 Mechanical Drawing A SOP-8 DIMENSION DIM 9 16 B 1 P 8 G R C D TS3404 M F K 5-5 MILLIMETERS MIN MAX INCHES MIN MAX A 4.80 5.00 0.189 0.196 B C 3.80 1.35 4.00 1.75 0.150 0.054 0.157 0.068 D 0.35 0.49 0.014 0.019 F G 0.40 1.25 1.27 (typ) 0.016 0.049 0.05 (typ) 0.004 K 0.10 M P 0 5.80 7 6.20 0 0.229 7 0.244 R 0.25 0.50 0.010 0.019 o 0.25 o o 2003/12 rev. A 0.009 o