ST1S12xx Synchronous rectification with enable, 0.7 A, 1.7 MHz fixed or adjustable step-down switching regulator in TSOT23-5L Features ■ Step-down current mode PWM (1.7 MHz) DCDC converter ■ 3% DC output voltage tolerance ■ Synchronous rectification ■ Fixed output voltage 1.2 V, 1.8 V, and ADJ (available on request 1.5 V, 2.5 V and 3.3 V) ■ Enable function ■ Internal soft start ■ Typical efficiency: > 90% ■ 0.7 A output current capability ■ Not switching quiescent current: max 600 µA over temperature range ■ RDSON typ. 250 mΩ and 400 mΩ ■ Uses tiny capacitors and inductors ■ Operative junction temp. -40°C to 125°C ■ Available in TSOT23-5L package TSOT23-5L required. Moreover, a low output ripple is guaranteed by the current mode PWM topology and by the use of low ESR SMD ceramic capacitors. The device is thermally protected and the current is limited to prevent damage due to accidental short-circuit. The ST1S12Gxx is available in the TSOT23-5L package. Description The ST1S12Gxx is a step down DC-DC converter optimized for powering low-voltage digital cores in HDD applications and, generally, to replace the high current linear solution when the power dissipation may cause high heating of the application environment. It provides up to 0.7 A over an input voltage range of 2.5 V to 5.5 V. A high switching frequency (1.7 MHz) allows the use of tiny surface-mount components. In addition to the resistor divider to set the output voltage value, only an inductor and two capacitors are Table 1. Device summary Part numbers Order codes Package ST1S12XX ST1S12GR TSOT23-5L ST1S12XX12 ST1S12G12R TSOT23-5L ST1S12XX18 ST1S12G18R (1) TSOT23-5L 1. Available on request. February 2008 Rev 2 1/20 www.st.com 20 Contents ST1S12xx Contents 1 Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6 Application notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 8 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2/20 ST1S12xx Schematic 1 Schematic Figure 1. Schematic diagram VIN UVLO + I_SEN Rsense - Σ VSUM Comp VRST VSET MOSFET CONTROL LOGIC VDRV_P Driver OSC SW VC + DMD DMD - gm + - SHUT DOWN VDRV_N Driver SOFT START REF1 FB/VO EN Gnd 3/20 Pin configuration ST1S12xx 2 Pin configuration Figure 2. Pin connections (top view) Table 2. Pin description Pin n° Symbol 1 EN 2 GND 3 SW Switching pin 4 VIN Input supply pin 5 FB/VO 4/20 Name and function Enable pin System ground Feedback voltage / or output voltage ST1S12xx Maximum ratings 3 Maximum ratings Table 3. Absolute maximum ratings Symbol Parameter Value Unit -0.3 to 7 V VIN Positive power supply voltage VEN Enable voltage -0.3 to VIN + 0.3 V Max. voltage of output pin -0.3 to VIN + 0.3 V Feedback voltage -0.3 to 3 V VO Output voltage (for VO > 1.6V) -0.3 to 6 V TJ Max junction temperature -40 to 150 °C TSTG Storage temperature range -65 to 150 °C TLEAD Lead temperature (soldering) 10 sec 260 °C SWITCH Voltage VFB/VO Note: Absolute maximum ratings are the values beyond which damage to the device may occur. Functional operation under these conditions is not implied. Table 4. Thermal data Symbol Parameter Value Unit RthJA Thermal resistance junction-ambient 220 °C/W RthJC Thermal resistance junction-case 110 °C/W Table 5. Symbol ESD ESD performance Parameter Test conditions Value Unit HBM 2 kV MM 0.3 kV ESD protection voltage 5/20 Electrical characteristics ST1S12xx 4 Electrical characteristics Table 6. Electrical characteristics for ST1S12G VIN =VEN = 3.6 V, CIN = 4.7 µF, CO =10 µF, L = 2.2 µH, TJ = -40 to 125 °C (unless otherwise specified. Typical values are referred to 25 °C) Symbol Parameter FB Feedback voltage IFB VFB pin bias current VIN Minimum input voltage IQ Quiescent current IO Output current Test conditions TJ =-40 to 125°C Min. Typ. Max. Unit 582 600 618 V 50 nA -50 IO= 10mA to 0.7A 2.5 VIN =VEN, VFB=0.65V V 500 VEN = 0, T = -40°C to 85°C VEN Enable threshold IEN Enable pin current VIN = 2.5 to 5.5V Note 1 0.7 Device ON, VIN = 2.5 to 5.5V 1.5 VIN = 2.5V to 5.5V Note 1 %VO/ΔIO Reference load regulation IO = 10mA to 700mA Note 1 PWMfS PWM switching frequency DMAX µA 1 µA A V Device OFF %VO/ΔVIN Reference line regulation 600 0.5 0.05 1 µA 0.1 %VO/ΔVIN 0.0025 0.005 1.16 1.7 Maximum duty cycle %VO/mA 2.08 MHz 100 % RDSON-N NMOS switch on resistance ISW = 100 mA 0.25 0.4 Ω RDSON-P PMOS switch on resistance ISW = 100 mA 0.25 0.45 Ω Note 1 1.6 IO = 10mA to 100mA, VO = 1.8V 80 IO = 100mA to 0.7A, VO = 1.8V 90 ISWL Switching current limitation ν Efficiency Note 1 TSHDN Thermal shutdown % 130 Thermal shutdown hysteresis THYS A 150 °C 15 °C %VO/ΔIO Load transient response IO = 100mA to 700mA, TA = 25°C tR = tF ≥ 200ns, CO=22µF Note 1 -5 +5 %VO %VO/ΔIO Short circuit removal response IO = 10mA to IO=short, TA = 25°C Note 1 -10 +10 %VO Note: 6/20 1 Guaranteed by design, but not tested in production. ST1S12xx Table 7. Electrical characteristics Electrical characteristics for ST1S12G12 VIN =VEN = 3 V, CIN = 4.7 µF, CO =10 µF, L = 2.2 µH, TJ = -40 to 125 °C (unless otherwise specified. Typical values are referred to 25 °C) Symbol Parameter OUT Output feedback pin IO VO pin bias current VIN Minimum input voltage IQ Quiescent current IO Output current Test conditions TJ =-40 to 125°C IO= 10mA to 0.7A Min. Typ. Max. Unit 1.164 1.2 1.236 V 15 20 µA 2.5 VIN =VEN, VFB=1.5V V 500 VEN = 0, T = -40°C to 85°C VEN Enable threshold IEN Enable pin current VIN = 2.5 to 5.5V Note 1 0.7 Device ON, VIN = 2.5 to 5.5V 1.5 VIN = 2.5V to 5.5V Note 1 %VO/ΔIO Reference load regulation IO = 10mA to 700mA Note 1 PWMfS PWM switching frequency µA 1 µA A V Device OFF %VO/ΔVIN Reference line regulation 600 0.5 0.05 1 µA 0.1 %VO/ΔVIN 0.0025 0.005 1.16 %VO/mA 1.7 2.08 MHz RDSON-N NMOS switch on resistance ISW = 100 mA 0.25 0.4 Ω RDSON-P PMOS switch on resistance ISW = 100 mA 0.25 0.45 Ω Note 1 1.6 IO = 10mA to 100mA 80 IO = 100mA to 0.7A 85 Switching current limitation ISWL ν Efficiency Note 1 Thermal shutdown TSHDN % 130 Thermal shutdown hysteresis THYS A 150 °C 15 °C %VO/ΔIO Load transient response IO = 100mA to 700mA, TA = 25°C tR = tF ≥ 200ns, CO=22µF Note 1 -5 +5 %VO %VO/ΔIO Short circuit removal response IO = 10mA to IO=short, TA = 25°C Note 1 -10 +10 %VO Note: 1 Guaranteed by design, but not tested in production. 7/20 Electrical characteristics Table 8. ST1S12xx Electrical characteristics for ST1S12G18 VIN =VEN = 3.6 V, CIN = 4.7 µF, CO =10 µF, L = 2.2 µH, TJ = -40 to 125 °C (unless otherwise specified. Typical values are referred to 25 °C) Symbol Parameter OUT Output feedback pin IO VO pin bias current VIN Minimum input voltage IQ Quiescent current IO Output current Test conditions TJ =-40 to 125°C IO= 10mA to 0.7A Min. Typ. Max. Unit 1.746 1.8 1.854 V 15 20 µA 2.5 VIN =VEN, VFB=2V V 500 VEN = 0, T = -40°C to 85°C VEN Enable threshold IEN Enable pin current VIN = 2.5 to 5.5V Note 1 0.7 Device ON, VI = 2.5 to 5.5V 1.5 VIN = 2.5V to 5.5V Note 1 %VO/ΔIO Reference load regulation IO = 10mA to 700mA Note 1 PWMfS PWM switching frequency µA 1 µA A V Device OFF %VO/ΔVIN Reference line regulation 600 0.5 0.05 1 µA 0.1 %VO/ΔVIN 0.0025 0.005 1.16 %VO/mA 1.7 2.08 MHz RDSON-N NMOS switch on resistance ISW = 100 mA 0.25 0.4 Ω RDSON-P PMOS switch on resistance ISW = 100 mA 0.25 0.45 Ω Note 1 1.6 IO = 10mA to 100mA 80 IO = 100mA to 0.7A 90 Switching current limitation ISWL ν Efficiency Note 1 Thermal shutdown TSHDN % 130 Thermal shutdown hysteresis THYS A 150 °C 15 °C %VO/ΔIO Load transient response IO = 100mA to 700mA, TA = 25°C tR = tF ≥ 200ns, CO=22µF Note 1 -5 +5 %VO %VO/ΔIO Short circuit removal response IO = 10mA to IO=short, TA = 25°C Note 1 -10 +10 %VO Note: 8/20 1 Guaranteed by design, but not tested in production. ST1S12xx Typical application 5 Typical application Figure 3. Application circuit 9/20 Application notes 6 ST1S12xx Application notes The ST1S12Gxx is an adjustable current mode PWM step-down DC-DC converter with internal 0.7 A power switch, packaged in TSOT23-5L. This device is a complete 0.7 A switching regulator, with its internal compensation eliminating the need for additional components. Because the ST1S12Gxx an adjustable regulator, the output voltage is determined by an external resistor divider. The desired value is derived by the following equation: VO = VFB[1+R1/R2] For the device to function only a few component are required: an inductor, two capacitors and the resistor divider. The inductor selected must be capable of non saturation at peak current level. Moreover, its value can be selected taking into account that a large inductor value increases efficiency at low output current and reduces output voltage ripple, while a smaller inductor can be used when it is important to reduce package size and the total cost of the application. Finally, the ST1S12Gxx has been designed to work properly with X5R or X7R SMD ceramic capacitors both at the input and at the output. These types of capacitors, due to their very low series resistance (ESR), minimize the output voltage ripple. Other low ESR capacitors can be used according to the need of the application without compromising the correct functioning of the device. 10/20 ST1S12xx Typical performance characteristics 7 Typical performance characteristics Figure 4. Unless otherwise specified, refer to the typical application circuit under the following conditions: CIN = 4.7 µF, COUT = 10 µF, L = 2.2 µH Voltage feedback vs temperature Figure 5. Drop vs temperature 650 0.5 VIN=VEN=3.6V, IOUT=10mA, VOUT=1.8V IOUT=700mA, VOUT=2.7V, Duty cycle=100% 0.4 Drop [V] VFB [mV] 630 610 590 0.3 0.2 0.1 570 0 550 -75 -50 -25 0 25 50 75 100 125 150 -75 175 -50 -25 0 25 T [°C] Figure 6. Oscillator frequency vs temperature Figure 7. VIN=VEN=3.6V, VFB=0.65V, VOUT=1.8V Efficiency [%] PWM freq.[MHz] 2.3 2.1 1.9 1.7 1.5 1.3 1.1 -75 -50 -25 0 25 50 75 100 90 80 70 60 50 40 30 20 10 0 100 125 150 175 0.1 Figure 9. VIN=VEN=3.6V, IOUT=from 10mA to 700mA, VOUT=1.8V 0 0.1 0.2 0.3 100 125 150 175 VIN=VEN=3V, IOUT=from 10mA to 700mA, VOUT=1.2V 0 Efficiency [%] Efficiency [%] Efficiency vs output current 100 90 80 70 60 50 40 30 20 10 0 75 Efficiency vs output current 0.2 0.3 T [°C] Figure 8. 50 T [°C] 0.4 IOUT [A] 0.5 0.6 0.7 0.4 IOUT [A] 0.5 0.6 0.7 0.8 Efficiency vs temperature 100 90 80 70 60 50 40 30 20 10 0 IOUT=100mA IOUT=700mA VIN=VEN=3.6V, VOUT=1.8V -75 -50 -25 0 25 50 75 100 125 150 175 T [°C] 11/20 Typical performance characteristics ST1S12xx 100 90 80 70 60 50 40 30 20 10 0 Figure 11. Supply current vs temperature 8 IOUT=100mA VIN=VEN=3V, VOUT=1.2V, No Load 7 ISUPPLY [mA] Efficiency [%] Figure 10. Efficiency vs temperature IOUT=700mA -50 -25 0 25 5 4 3 2 VIN=VEN=3V, VOUT=1.2V -75 6 1 50 75 100 125 150 -75 175 -50 -25 0 25 VIN=VEN=3.6V, VFB=0.65V, CIN=COUT=10µF, No Switching -75 -50 -25 0 25 50 75 100 125 150 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 125 150 175 VIN=2.5V, IOUT=10mA, CIN=COUT=10µF, VOUT=1.8V -75 175 -50 -25 0 25 50 75 100 125 150 175 T [°C] Figure 14. Enable voltage vs temperature Figure 15. Reference line regulation vs temperature 0.6 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 ON OFF LINE [%VOUT/ VIN] VEN [V] 100 ON OFF T [°C] VIN=5.5V, IOUT=10mA, CIN= COUT=10µF, VOUT=1.8V VIN=VEN= 2.5V to 5.5V, CIN=COUT=10µF, IOUT=10mA, VOUT=1.8V 0.4 0.2 -0 -0.2 -0.4 -0.6 -75 -50 -25 0 25 50 T [°C] 12/20 75 Figure 13. Enable voltage vs temperature VEN [V] ISUPPLY [µA] Figure 12. Quiescent current vs temperature 510 490 470 450 430 410 390 370 350 50 T [°C] T [°C] 75 100 125 150 175 -75 -50 -25 0 25 50 T [°C] 75 100 125 150 175 ST1S12xx Typical performance characteristics Figure 16. Reference load regulation vs temperature Figure 17. NMOS switch on resistance vs temperature 0.7 VIN=3.6V, IOUT from 10mA to 0.7A, VOUT=1.8V VIN=VEN=3.6V, CIN=COUT=10µF, VOUT=1.2V 0.6 0.004 RDSON-N [ohm] LOAD [%VOUT/mA] 0.005 0.003 0.002 0.001 0.5 0.4 0.3 0.2 0.1 0 0 -75 -50 -25 0 25 50 75 100 125 150 -75 175 -50 -25 0 25 T [°C] Figure 18. PMOS switch on resistance vs temperature 0.7 125 150 175 2.3 2 ISW [A] RDSON-P [ohm] 100 2.6 0.5 0.4 0.3 1.7 1.4 0.2 1.1 0.1 0.8 0 0.5 -75 -50 -25 0 25 50 75 100 125 150 VIN=VEN=3.6V, CIN=COUT=10µF, VOUT=1.8V -75 175 -50 -25 0 25 Figure 20. Switching current limitation vs input voltage VIN=VEN from 2.5 to 5.5V, CIN=COUT=10µF, VOUT=1.8V VOUT [V] 2 1.5 1 0.5 0 2 2.5 3 3.5 4 VIN [V] 75 100 125 150 175 Figure 21. Output voltage vs input voltage 3 2.5 50 T [°C] T [°C] ISW [A] 75 Figure 19. Switching current limitation vs temperature VIN=VEN=3.6V, CIN=COUT=10µF, VOUT=1.2V 0.6 50 T [°C] 4.5 5 5.5 6 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 125°C 25°C 0°C -25°C -40°C VIN=VEN from 0 to 5.5V, IOUT=700mA, CIN=COUT=10µF 0 1 2 3 4 5 6 VIN [V] 13/20 Typical performance characteristics ST1S12xx Figure 22. Line transient Figure 23. Load transient VOUT VIN IOUT VOUT VIN = VEN from 4.5 V to 5.5 V, IOUT = 350 mA, CIN = COUT = 10µF, VOUT = 1.8 V VIN = VEN = 3 V, IOUT = 100 mA to 700 mA, tR = tF = 200 ns Figure 24. Start-up transient Figure 25. Enable transient VIN VOUT VIN = VEN from 0 V to 6 V, IOUT = 350 mA, CIN = COUT = 10µF, VOUT = 1.8 V 14/20 VEN VOUT VIN =3.6, VEN from 0 V to 2 V, IOUT = 350 mA, CIN = COUT = 10µF, VOUT = 1.8 V ST1S12xx 8 Package mechanical data Package mechanical data In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a lead-free second level interconnect. The category of second level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com. 15/20 Package mechanical data ST1S12xx TSOT23-5L mechanical data mm. mils. Dim. Min. Typ. A Max. Min. Typ. Max. 1.1 43.3 3.9 A1 0 0.1 A2 0.7 1.0 27.6 39.4 b 0.3 0.5 11.8 19.7 C 0.08 0.2 3.1 7.9 D 2.9 114.2 E 2.8 110.2 E1 1.6 63.0 e 0.95 37.4 e1 1.9 74.8 L 0.3 0.6 11.8 23.6 7282780B 16/20 ST1S12xx Package mechanical data Tape & reel TSOT23-5L mechanical data mm. inch. Dim. Min. Typ. A Max. Min. Typ. 180 13.0 7.086 C 12.8 D 20.2 0.795 N 60 2.362 T 13.2 Max. 0.504 0.512 14.4 0.519 0.567 Ao 3.13 3.23 3.33 0.123 0.127 0.131 Bo 3.07 3.17 3.27 0.120 0.124 0.128 Ko 1.27 1.37 1.47 0.050 0.054 0.0.58 Po 3.9 4.0 4.1 0.153 0.157 0.161 P 3.9 4.0 4.1 0.153 0.157 0.161 17/20 Package mechanical data ST1S12xx Figure 26. TSOT23-5L footprint recommended data Table 9. Footprint data Values 18/20 mm. inch. A 3.50 0.138 B 1.10 0.043 C 0.60 0.024 D 0.95 0.037 E 1.20 0.047 F 2.30 0.090 ST1S12xx Revision history 9 Revision history Table 10. Document revision history Date Revision Changes 10-Jan-2008 1 Initial release. 01-Feb-2008 2 Modified: Figure 3 on page 9. 19/20 ST1S12xx Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. 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