Jose Fernandez

®

L4972A L4972AD
2A SWITCHING REGULATOR

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2A OUTPUT CURRENT 5.1V TO 40V OUTPUT VOLTAGE RANGE 0 TO 90% DUTY CYCLE RANGE INTERNAL FEED-FORWARD LINE REG. INTERNAL CURRENT LIMITING PRECISE 5.1V ± 2% ON CHIP REFERENCE RESET AND POWER FAIL FUNCTIONS INPUT/OUTPUT SYNC PIN UNDER VOLTAGE LOCK OUT WITH HYSTERETIC TURN-ON PWM LATCH FOR SINGLE PULSE PER PERIOD VERY HIGHEFFICIENCY SWITCHING FREQUENCY UP TO 200KHz THERMAL SHUTDOWN CONTINUOUS MODE OPERATION

MULTIPOWER BCD TECHNOLOGY

POW ERDIP (16 + 2 + 2)

SO20

ORDERING NUMBERS : L4972A (Powerdip) L4972AD (SO20)

DESCRIPTION The L4972Aisa stepdownmonolithicpower switching regulatordelivering 2A at a voltagevariable from 5.1 to 40V. Realized with BCD mixed technology, the device uses a DMOS outputtransistor to obtain very high efficiency and very fast switching times. Features of BLOCK DIAGRAM

the L4972A include reset and power fail for microprocessors, feed forward line regulation, soft start, limiting current and thermal protection. The device is mountedin a Powerdip16 + 2 + 2 and SO20large plastic packages and requires few external components. Efficient operation at switching frequencies upto 200KHz allows reduction in the size and cost of external filter component.

June 2000

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This is advanced information on a new product now in development or undergoing evaluation. Details are subject to change without notice.

L4972A-L4972AD
ABSOLUTE MAXIMUM RATINGS
Symbo l V11 V11 V20 I20 VI V4 , V 8 V3 I3 V2, V 7, V 9, V10 I2 I7 I8 Ptot TJ, Tstg
(*) SO-20

Parameter InputVoltage Input Operating Voltage Output DC Voltage Output Peak Voltage at t = 0.1µs f = 200khz Maximum Output Current Boostrap Voltage Boostrap Operating Voltage Input Voltage at Pins 4, 12 Reset Output Voltage Reset Output Sink Current Input Voltage at Pin 2, 7, 9, 10 Reset Delay Sink Current Error Amplifier Output Sink Current Soft Start Sink Current Total Power Dissipation at TPINS ≤ 90°C at Tamb = 70°C (No copper area on PCB) Junction and Storage Temperature

Valu e 55 50 -1 -5 Internally Limited 65 V11 + 15 12 50 50 7 30 1 30 5 / 3.75(*) 1.3/1 (*) -40 to 150

Unit V V V V V V V V mA V mA A mA W W °C

PIN CONNECTION (top view)

THERMAL DATA
Symb ol Rth j-pins Rth j-amb Parameter Thermal Resistance Junction-Pins Thermal Resistance Junction-ambient max max Po werdip 12°C/W 60°C/WSO- 20 16°C/W 80°C/W

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L4972A-L4972AD
PIN FUNCTIONS
No 1 2 3 4 Name BOOTSTRAP RESET DELAY RESET OUT RESET INPUT F unctio n A Cboot capacitor connected between this terminal and the output allows to drive properly the internal D-MOS transistor. A Cd capacitor connected between this terminal and ground determines the reset signal delay time. Open Collector Reset/power Fail SignalOutput. This output is high when the supply and the output voltages are safe. Input of Power Fail Circuit. The threshold is 5.1V. It may be connected via a divider to the input for power fail function. It mustbe connected to the pin 14 an external 30KΩ resistor when power fail signal not required. Common Ground Terminal A series RC network connected between this terminal and ground determines theregulation loop gain characteristics. Soft Start Time Constant. A capacitor is connected between thi sterminal and ground to define the soft start time constant. The Feedback Terminal of the Regulation Loop. The output is connected directly to this terminal for 5.1V operation; It is connected via a divider for higher voltages. Multiple L4972A’s are synchronized by connecting pin 10 inputs together orvia an external syncr. pulse. Unregulated Input Voltage. Not Connected. 5.1V Vref Device Reference Voltage. Internal Start-up Circuit to Drive the Power Stage. Rosc. External resistor connected to ground determines the constant charging current of C osc. Cosc. External capacitor connected to ground determines (with Rosc) the switching frequency. Regulator Output.

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