L5972D STMICROELECTRONICS | Alldatasheet

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Technical content

■ 2A INTERNAL SWITCH ■ OPERATING INPUT VOLTAGE FROM 4.4V TO 36V ■ OUTPUT VOLTAGE ADJUSTABLE FROM 1.235V TO 35V ■ LOW DROPOUT OPERATION: 100% DUTY CYCLE ■ 250KHz INTERNALLY FIXED FREQUENCY ■ VOLTAGE FEEDFORWARD ■ ZERO LOAD CURRENT OPERATION ■ INTERNAL CURRENT LIMITING ■ PROTECTION AGAINST FEEDBACK DISCONNECTION ■ THERMAL SHUTDOWN APPLICATIONS: ■ CONSUMER: STB, DVD, TV, VCR,CAR RADIO, LCD MONITORS ■ NETWORKING: XDSL, MODEMS,DC-DC MODULES ■ COMPUTER: PRINTERS, AUDIO/GRAPHIC CARDS, OPTICAL STORAGE, HARD DISK DRIVE ■ INDUSTRIAL: CHARGERS, CAR BATTERY DC-DC CONVERTERS

DESCRIPTION

The L5972D is a step down monolithic power switch- ing regulator with a minimum switch current limit of 2A so it is able to deliver more than 1.5A DC current to the load depending on the application conditions. The output voltage can be set from 1.235V to 35V. The device uses an internal P-Channel D-MOS tran- sistor (with a typical Rdson of 250m Ω ) as switching element to minimize the size of the external compo- nents. An internal oscillator fixes the switching frequency at 250KHz. Having a minimum input voltage of 4.4V only, it is particularly suitable for 5V bus, available in all com- puter related applications. Pulse by pulse current limit with the internal frequen- cy modulation offers an effective constant current short circuit protection. SO8 (4+2+2) ORDERING NUMBERS: L5972D (SO8) L5972D013TR (Tape & Reel) 2A SWITCH STEP DOWN SWITCHING REGULATOR TEST APPLICATION CIRCUIT D03IN1436 4 5 L5972D 10mF 35V CERAMIC 100mF 10V VOUT=3.3VVIN = 4.4V to 35V 5.6K 3.3KR3 4.7K 22nF 220pF L1 33mH STPS2L40UCOMP VCC OUT FB GND

(*) Package mounted on board (4cm2 ground-plane) ABSOLUTE MAXIMUM RATINGS N° Pin Function 1 OUT Regulator Output. 2,3,6,7 GND Ground. 4 COMP E/A output for frequency compensation. 5 FB Feedback input. Connecting directly to this pin results in an output voltage of 1.23V. An external resistive divider is required for higher output voltages. 8 VCC Unregulated DC input voltage. Symbol Parameter Value Unit R th (j-amb) Thermal Resistance Junction to ambient Max. 65 (*) °C/W Symbol Parameter Value Unit V8 Input Voltage 40 V V1 Out pin DC voltage Out pin peak voltage at Δt = 0.1µs -1 to 40 -5 to 40 V V I1 Maximum output current int. limit. V4, V5 Analog pins 4 V Ptot Power dissipation at Tamb ≤ 70°C 1.2 W Tj Operating junction temperature range -40 to 150 °C Tstg Storage temperature range -55 to 150 °C OUT GND GND COMP VCC GND GND FB D02IN1367

ELECTRICAL CHARACTERISTICS (Tj = 25°C, VCC = 12V, unless otherwise specified.) (*) Specification Referred to Tj from -40 to 125°C. Symbol Parameter Test Condition Min. Typ. Max. Unit VCC Operating input voltage range Vo = 1.235V; Io = 1.5A * 4.4 36 V Vd Dropout voltage V CC = 4.4V; Io = 1.5A * 0.375 0.75 V Il Maximum limiting current V CC = 4.4V to 36V * 2 2.5 3 A fs Switching frequency * 212 250 280 KHz 225 250 275 KHz Duty cycle 0 100 % DYNAMIC CHARACTERISTICS (see test circuit ). V5 Voltage feedback 4.4V < V CC < 36V, 20mA < IO < 1.5A 1.220 1.235 1.25 V * 1.198 1.235 1.272 V h Efficiency V O = 5V, VCC = 12V 90 % DC CHARACTERISTICS Iqop Total operating quiescent current * 3 5 mA Iq Quiescent current Duty Cycle = 0; V FB = 1.5V 2.5 mA ERROR AMPLIFIER V OH High level output voltage VFB = 1V 3.5 V VOL Low level output voltage VFB = 1.5V 0.4 V Io source Source output current V COMP = 1.9V; VFB = 1V 200 300 µA Io sink Sink output current V COMP = 1.9V; VFB = 1.5V 1 1.5 mA Ib Source bias current 2.5 4 µA DC open loop gain R L = ∞ 50 65 dB gm Transconductance I comp = -0.1mA to 0.1mA VCOMP = 1.9V 2.3 mS

is adjustable from 1.235V to Vcc. Figure 7. Demo board Application Circuit Table 1. Component List

DIM. mm inch A 1.75 0.069 a1 0.1 0.25 0.004 0.010 a2 1.65 0.065 a3 0.65 0.85 0.026 0.033 b 0.35 0.48 0.014 0.019 b1 0.19 0.25 0.007 0.010 C 0.25 0.5 0.010 0.020 c1 45 ° (typ.) D (1) 4.8 5.0 0.189 0.197 E 5.8 6.2 0.228 0.244 e 1.27 0.050 e3 3.81 0.150 F (1) 3.8 4.0 0.15 0.157 L 0.4 1.27 0.016 0.050 M 0.6 0.024 S8 ° (max.) (1) D and F do not include mold flash or protrusions. Mold flash or potrusions shall not exceed 0.15mm (.006inch). SO8 OUTLINE AND MECHANICAL DATA

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  2003 STMicroelectronics - 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 L5972D