ST735S ST735T 300kHz, -5V/ADJ INVERTING, NEGATIVE OUTPUT CURRENT-MODE PWM REGULATOR ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ CONVERTS +4.0V TO + 6.2V INPUT TO -5V OUTPUT (735S) OR +3.5V TO + 9.0V TO A NEGATIVE ADJUSTABLE OUTPUT (735T) 1W GUARANTEED OUTPUT POWER 72% TYPICAL EFFICIENCY 0.8mA QUIESCENT CURRENT 1µA SHUTDOWN MODE 300KHZ FIXED FREQUENCY OSCILLATOR CURRENT MODE PWM CONVERTER LOW NOISE AND JITTER SOFT START SIMPLE APPLICATION CIRCUIT UNDERVOLTAGE LOCKOUT (735S) DESCRIPTION The ST735S/ST735T is a Bi-CMOS, inverting switch mode DC-DC regulator with internal Power MOSFET that generates a fixed -5V (S version) or a negative adjustable (T version) output voltage from a 4V (3.5V for the 735T) to 6.2V input voltage (9V for the 735T); is guaranteed an output current of 200mA for inputs greater than 4.5V. The quiescent current for this device is typically of DIP-8 SO-8 0.8mA and, in shutdown mode it is reduced to 1µA. These power-conserving features, along with high efficiency and applications circuits, thaT lend itself to minaturization, make the ST735S/ST735T excellent in a broad range of on-card, HDD and portable equipment applications. These device employ a high performance current mode pulse with modulation (PWM) control scheme to provide tight output voltage regulation and low noise. The fixed frequency oscillator is factory trimmed to 300KHz, allowing for easy noise filtering. The regulator in production is tested to guarantee an output accuracy within ±5% over all specified conditions. SCHEMATIC DIAGRAM October 2002 1/11 ST735S/ST735T ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit VIN DC Input Voltage (VIN to GND) for ST735S -0.3 to +7 V VIN DC Input Voltage (VIN to GND) for ST735T (Note 1) -0.3 to +11 V SHDN Shutdown Voltage (SHDN to GND) -0.3 to VIN+0.3 V VLX Switch Voltage (Lx to VIN) Feedback Voltage (VOUT to GND) -12.5 to +0.3 V -11 to +0.3 V -11 to +0.3 V -0.3 to V++0.3 V VFB VOUT Output Voltage (VOUT to GND) Other Input Voltage (SS, CC to GND) Peack Switch Current ILX Ptot Power Dissipation at Tj = 70°C DIP-8 SO-8 2 A 725 470 mW Tstg Storage Temperature Range -55 to +150 °C Top Operating Junction Temperature Range -40 to +125 °C Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied. Note 1: The input to output differential voltage is limited to VIN+|VOUT|<12.7V THERMAL DATA Symbol Rthj-case Parameter Thermal Resistance Junction-case DIP-8 SO-8 Unit 2 8 °C/W CONNECTION DIAGRAM (top view) PIN DESCRIPTION 2/11 Pin N° Symbol 1 SHDN Name and Function 2 VREF Reference Output Voltage 3 4 5 SS CC VOUT Soft Start Compensation Input Negative Output Voltage 6 7 8 GND LX VIN Ground Switch Output Positive Supply - Voltage Input SHUT-DOWN Control (VCC=ON GND=Shutdown ST735S/ST735T ORDERING CODES TYPE DIP-8 SO-8 SO-8 (T&R) ST735S ST735T ST735SCN ST735TCN ST735SCD ST735TCD ST735SCD-TR ST735TCD-TR TYPICAL APPLICATION CIRCUIT NOTE: 1) All capacitors are X7R ceramic 2) C5 can be omitted if are used higher values for the input and output capacitors (suggested C2=47µF, C1=100µF). 3) R1 and R2 must be placed is ST735T applications only. Their values are calculated by the following formula R2=(|VOUT|/VREF)xR1. For R1 can be chosen any value between 2kΩ and 20kΩ APPLICATION CIRCUIT To achieve the best performances from switching power supply topology, particular care to layout drawing is needed, in order to minimize EMI and obtain low noise. Moreover, jitter free operation ensures the full device functionality. Layout design proposed on demoboard helps to lower the developing time. Wire lengths must be minimized, filter and bypass capacitors must be low ESR type, placed as close as possible to the integrated circuit. The 4.7µF (or 6.8µF) inductor must be chosen built on a core, taking care that saturation current should be higher than the peak LX switch current. See the Peak Inductor Current vs Output Current graph. PRINTED DEMOBOARD (not in scale) 3/11 ST735S/ST735T ELECTRICAL CHARACTERISTICS OF ST735S (Refer to test circuit, VIN=5V, CIN = 4.7µF, COUT = 10µF all X7R ceramic, L = 4.7µH (Note1) , IOUT=0mA, Tamb = -40 to 125°C, unless otherwise specified. Typical value are referred at Tamb= 25°C) Symbol VIN VOUT IOUT Parameter Test Conditions Input Voltage Output Voltage Output Current ISUPPLY Supply Current Typ. Max. 4 Unit 6.2 V VIN = 4.5V to 6.2V IOUT = 0 to 200mA Tamb= -40 to 125°C -5.25 -5 -4.75 V VIN = 4.0V to 6.2V IOUT = 0 to 175mA Tamb= -40 to 125°C -5.25 -5 -4.75 V VIN = 4.5V to 6.2V TJ= 0 to 125°C 200 275 VIN = 4.5V to 6.2V IOUT = 0 to 175mA Tamb= -40 to 125°C 175 VIN = 4.0V ISTANDBY Standby Current Min. VOUT = -5V mA mA 175 Includes Switch Current VSHDN = 0V mA 0.8 1.6 mA 1 10 µA ISC Short Circuit Current VIN = 5V 0.9 A IPEAK LX Max Peak Current (Note 2) 1.5 A VLO Undervoltage Lock-out 3.5 ∆VOUT Line Regulation VIN = 4.0V to 6.2V ∆VOUT Load Regulation Reference Voltage ∆VREF Reference Drift RDSON LX ON Voltage VREF ILEAK LX Leakage Current 4 V 0.1 %/V IOUT = 0 to 200mA 0.003 %/mA Tamb= 25°C (Note 3) 1.225 V Tamb= -40 to 125°C 50 ppm/°C VDS = 10V 0.5 Ω 1 µA ISH Shutdown Pin Current 1 µA VIL Shutdown Input Low Threshold Shutdown Input High Threshold Maximum Oscillator Frequency Efficency 0.25 V VIH fOSC ν RCC 2 IOUT = 100mA Compensation Pin Impedance on CC Pin Note 1: Utilize of 6.8µH permits to reach higher current capability at the same operating conditions Note2: Guaranteed by design, but not tested in production Note3 : Tested at IVREF = 125µA 4/11 V 300 KHz 72 % 7.5 KΩ ST735S/ST735T ELECTRICAL CHARACTERISTICS OF ST735T (Refer to test circuit, VIN=5V, CIN = 4.7µF, COUT = 10µF all X7R ceramic, L = 4.7µH (Note1) , IOUT=0mA, VO adjusted to -5V, Tamb = -40 to 125°C, unless otherwise specified. Typical value are referred at Tamb= 25°C) Symbol Parameter VIN Input Voltage VO Output Voltage IO Output Current Test Conditions ISUPPLY Supply Current Typ. Max. 3.5 Unit 9 V VIN = 4.5V to 6.2V IOUT = 0 to 200mA Tamb= -40 to 125°C -5.25 -5 -4.75 V VIN = 4.0V to 6.2V IOUT = 0 to 175mA Tamb= -40 to 125°C -5.25 -5 -4.75 V VIN = 4.5V to 6.2V Tamb= 0 to 125°C 200 275 VIN = 4.5V to 6.2V IOUT = 0 to 175mA Tamb= -40 to 125°C 175 VIN = 4.0V ISTANDBY Standby Current Min. VOUT = -5V mA mA 175 Includes Switch Current VSHDN = 0V mA 0.8 1.6 mA 1 10 µA ISC Short Circuit Current VIN = 5V 0.9 A IPEAK LX Max Peak Current (Note 2) 1.5 A VLO Undervoltage Lock-out 3.5 ∆VOUT Line Regulation VIN = 4.0V to 6.2V ∆VOUT Load Regulation Reference Voltage ∆VREF Reference Drift RDSON LX ON Voltage VREF ILEAK LX Leakage Current 4 V 0.1 %/V IOUT = 0 to 200mA 0.003 %/mA Tamb= 25°C (Note 3) 1.225 V Tamb= -40 to 125°C 50 ppm/°C VDS = 10V 0.5 Ω 1 µA ISH Shutdown Pin Current 1 µA VIL Shutdown Input Low Threshold Shutdown Input High Threshold Maximum Oscillator Frequency Efficency 0.25 V VIH fOSC ν RCC 2 IOUT = 100mA Compensation Pin Impedance on CC Pin V 300 KHz 72 % 7.5 KΩ Note 1: Utilize of 6.8µH permits to reach higher current capability at the same operating conditions Note2: Guaranteed by design, but not tested in production Note3 : Tested at IVREF = 125µA 5/11 ST735S/ST735T TYPICAL CHARACTERISTICS (Referred to typical application circuit, Tamb=25°C unless otherwise specified) Figure 1 : Output Voltage vs Temperature Figure 4 : Efficency vs Ouput Current Figure 2 : Reference Voltage vs Temperature Figure 5 : Efficency vs Low Ouput Current Figure 3 : Efficency vs Temperature Figure 6 : Supply Current vs Temperature 6/11 ST735S/ST735T Figure 7 : Supply Current vs Input Voltage for ST735S Figure 10 : Peack Inductor vs Output Current Figure 8 : Supply Current vs Input Voltage for ST734T Figure 11 : Switch Current Limit vs Soft Start Voltage Figure 9 : Shutdown Threshold vs Temperature Figure 12 : Oscillator Frequency Vs Temperature 7/11 ST735S/ST735T Figure 13 : LX On Resistance vs Temperature Figure 16 : Load Transient VI=5V, I O=20mA to 200mA, CI = 4.7µF, CO=100µF, tf=1µs Figure 14 : LX On Resistance vs Input Voltage Figure 17 : Load Transient VI=5V, I O=20mA to 200mA, CI = 4.7µF, CO=100µF, tr=1µs Figure 15 : Load Transient Figure 18 : Switching Waveform VI=5V, I O=20mA to 200mA, CI = 4.7µF, CO=100µF, tr=tf=1µs VI=5V, I O=100mA 8/11 ST735S/ST735T Plastic DIP-8 MECHANICAL DATA mm. inch DIM. MIN. A TYP MAX. MIN. 3.3 TYP. MAX. 0.130 a1 0.7 B 1.39 1.65 0.055 0.065 B1 0.91 1.04 0.036 0.041 b b1 0.028 0.5 0.38 0.020 0.5 D 0.015 0.020 9.8 0.386 E 8.8 0.346 e 2.54 0.100 e3 7.62 0.300 e4 7.62 0.300 F 7.1 0.280 I 4.8 0.189 L Z 3.3 0.44 0.130 1.6 0.017 0.063 P001F 9/11 ST735S/ST735T SO-8 MECHANICAL DATA DIM. mm. MIN. TYP A a1 inch MAX. MIN. TYP. 1.75 0.1 0.068 0.25 a2 MAX. 0.003 0.009 1.65 0.064 a3 0.65 0.85 0.025 0.033 b 0.35 0.48 0.013 0.018 b1 0.19 0.25 0.007 0.010 C 0.25 0.5 0.010 0.019 c1 45˚ (typ.) D 4.8 5.0 0.189 0.196 E 5.8 6.2 0.228 0.244 e 1.27 0.050 e3 3.81 0.150 F 3.8 4.0 0.149 0.157 L 0.4 1.27 0.015 0.050 M S 0.6 0.023 8˚ (max.) 0016023 10/11 ST735S/ST735T Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. © The ST logo is a registered trademark of STMicroelectronics © 2002 STMicroelectronics - Printed in Italy - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan - Malaysia - Malta - Morocco Singapore - Spain - Sweden - Switzerland - United Kingdom - United States. © http://www.st.com 11/11