Datasheet

ManualsBrandsST ManualsDC / DC Adjustable Switching RegulatorsSwitching Regulator, Multiwatt, 10A

L4970A

10A SWITCHING REGULATOR

10A OUTPUT CURRENT

5.1V TO 40V OUTPUT VOLTAGERANGE

0 TO 90% DUTY CYCLE RANGE

INTERNAL FEED-FORWARD LINE REGULA-

TION

INTERNAL CURRENT LIMITING

PRECISE 5.1V

2% ON CHIP REFERENCE

RESET AND POWER FAIL FUNCTIONS

SOFT START

INPUT/OUTPUT SYNC PIN

UNDER VOLTAGE LOCK OUT WITH HYS-

TERETICTURN-ON

PWM LATCH FOR SINGLE PULSE PER PE-

RIOD

VERY HIGH EFFICIENCY

SWITCHING FREQUENCY UP TO 500KHz

THERMAL SHUTDOWN

CONTINUOUS MODE OPERATION

DESCRIPTION

The L4970A is a stepdown monolithic power

switching regulator delivering 10A at a voltage

variable from 5.1 to 40V.

Realized with BCD mixed technology, the device

uses a DMOS output transistor to obtain very high

efficiency and very fast switching times. Features

of the L4970A include reset and power fail for mi-

croprocessors, feed forward line regulation, soft

start, limiting current and thermal protection. The

device is mounted in a 15-lead multiwatt plastic

power package and requires few external compo-

nents. Efficient operation at switching frequencies

up to 500KHz allows reduction in the size and

cost of external filter components.

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

June 2000



BLOCK DIAGRAM

Multiwatt15V

ORDERING NUMBER:

L4970A

MULTIPOWER BCD TECHNOLOGY

1/21

Summary of content (22 pages)

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 L4970A 10A SWITCHING REGULATOR 10A OUTPUT CURRENT 5.1V TO 40V OUTPUT VOLTAGE RANGE 0 TO 90% DUTY CYCLE RANGE INTERNAL FEED-FORWARD LINE REGULATION INTERNAL CURRENT LIMITING PRECISE 5.
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L4970A ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit V V9 Input Voltage 55 V9 Input Operating Voltage 50 V V7 Output DC Voltage Output Peak Voltage at t = 0.
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L4970A PIN FUNCTIONS No Name Function 1 OSCILLATOR Rosc. External resistor connected to ground determines the constant charging current of Cosc. 2 OSCILLATOR Cosc. External capacitor connected to ground determines (with Rosc) the switching frequency. 3 RESET INPUT 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 must be connected to the pin 14 an external 30KΩ resistor when power fail signal not required.
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L4970A Figure 1: Feedforward Waveform Figure 2: Soft Start Function Figure 3: Limiting Current Function 4/21
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L4970A stability of the loop can be adjusted by an external RC network connected to the output of the error amplifier. A voltage feedforward control has been added to the oscillator, this maintains superior line regulation over a wide input voltage range. Closing the loop directly gives an output voltage of 5.1V, higher voltages are obtained by inserting a voltage divider. At turn on output overcurrents are prevented by the soft start function (fig. 2).
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L4970A ELECTRICAL CHARACTERISTICS (Refer to the test circuit, T j = 25°C, Vi = 35V, R4 = 16KΩ, C9 = 2.2nF, fSW = 200KHz typ, unless otherwise specified) DYNAMIC CHARACTERISTICS Symbol Parameter Test Condition Min. Vi input Voltage Range (pin 9) Vo = Vref to 40V Io = 10A 15 Vo Output Votage Vi = 15V to 50V Io = 5A; Vo = Vref 5 ∆Vo Line Regulation Vi = 15V to 50V Io = 5A; Vo = Vref ∆Vo Load Regulation Vo = Vref Io = 3A to 6A Io = 2A to 10A Typ. Max. Unit Fig. 50 V 5 5.1 5.
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L4970A ELECTRICAL CHARACTERISTICS (continued) DC CHARACTERISTICS Symbol Parameter Test Condition Min. Typ. Max. 10 11 12 Unit Fig.
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L4970A ELECTRICAL CHARACTERISTICS (continued) RESET AND POWER FAIL FUNCTIONS Symbol Parameter Min. Typ. Max. Unit Fig. V11R Rising Threshold Voltage (pin 11) Vi = 15 to 50V V3 = 5.3V Test Condition Vref –120 Vref –100 Vref –80 V mV 7D V11F Falling Threshold Voltage (pin 11) Vi = 15 to 50V V3 = 5.3V 4.77 Vref –200 Vref –160 V mV 7D V5H Delay High Threshold Voltage Vi = 15 to 50V V14 = V11 V3 = 5.3V 4.95 5.1 5.
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L4970A Figure 6a: P.C. Board (components side) and Components Layout of Figure 5 (1:1 scale). PARTS LIST Table A R1 = 30KΩ C 1, C2 = 3300µF 63VL EYF (ROE R2 = 10KΩ C 3, C4, C5, C 6 = 2.2µF R3 = 15KΩ C 7 = 390pF Film R4 = 16KΩ C 8 = 22nF MKT 1817 (ERO) R5 = 22Ω 0,5W R6 = 4K7 C 9 = 2.2nF KP1830 R7 = 10Ω C 10 = 220nF MKT R8 = see tab. A C 11 = 2.2nF MP1830 R9 = OPTION **C12, C13, C14 = 220µF 40VL EKR R10 = 4K7 C 15 = 1µF Film V0 R9 R7 12V 15V 18V 24V 4.7kΩ 4.7kΩ 4.7kΩ 4.7kΩ 6.2kW 9.
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L4970A Figure 6b: P.C. Board (Back side) and Components Layout of the Circuit of Fig. 5.
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L4970A Figure 7A Figure 7B 11/21
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L4970A Figure 7D Figure 7C 12/21
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L4970A Figure 8: Quiescent Drain Current vs. Supply Voltage (0% duty cycle - see fig. 7A). Figure 9: Quiescent Drain Current vs. Junction Temperature (0% duty cycle). Figure 10: Quiescent Drain Current vs. Duty Cycle Figure 11: Reference Voltage (pin14) vs. Vi (see fig. 7) Figure 12: Reference Voltage (pin 14) vs. Junction Temperature (see fig. 7) Figure 13: Reference Voltage (pin15) vs. Vi (see fig.
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L4970A Figure 14: Reference Voltage (pin 15) vs. Junction Temperature (see fig. 7) Figure 15: Reference Voltage 5.1V (pin 14) Supply Voltage Ripple Rejection vs. Frequency Figure 16: Switching Frequency vs. Input Voltage (see fig. 5) Figure 17: Switching Frequency vs. Junction Temperature (see fig 5) Figure 18: Switching Frequency vs. R4 (see fig. 5) Figure 19: Max. Duty Cycle vs.
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L4970A Figure 20: Supply Voltage Ripple Rejection vs. Frequency (see fig. 5) Figure 21: Line Transient Response (see fig. 5) Figure 22: Load Transient Response (see fig. 5) Figure 23: Dropout Voltage Between Pin 9 and Pin 7 vs. Current at Pin 7 Figure 24: Dropout Voltage Between Pin 9 and Pin 7 vs. Junction Temperature Figure 25: Power Dissipation (device only) vs.
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L4970A Figure 26: Power Dissipation (device only) vs. Output Voltage Figure 27: Heatsink Used to Derive the Device’s Power Dissipation Tcase − Tamb Rth - Heatsink = Pd Figure 28: Efficiency vs. Output Current Figure 29: Efficiency vs. Output Voltage Figure 30: Efficiency vs. Output Voltage 16/21 Figure 31: Open Loop Frequency and Phase Response of Error Amplifier (see fig.
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L4970A Figure 32: Power Dissipation Derating Curve Figure 33: A5.1V/12V Multiple Supply.
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L4970A Figure 34: 5.1V / 10A Low Cost Application Figure 35: 10A Switching Regulator, Adjustable from 0V to 25V.
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L4970A Figure 36: L4970A’s Sync.
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L4970A DIM. MIN. mm TYP. A B C D E F G G1 MIN. inch TYP. 2.65 1.6 1.27 17.78 19.6 L L1 L2 L3 L4 L7 M 21.9 21.7 17.65 17.25 10.3 2.65 4.25 22.2 22.1 M1 S S1 Dia1 4.63 1.9 1.9 3.65 5.08 MAX. 0.197 OUTLINE AND MECHANICAL DATA 0.104 0.063 1 0.49 0.66 1.02 17.53 H1 H2 20/21 MAX. 5 0.039 0.55 0.75 1.52 18.03 0.019 0.026 0.040 0.690 0.050 0.700 0.022 0.030 0.060 0.710 0.772 20.2 17.5 10.7 4.55 0.795 22.5 22.5 18.1 17.75 10.9 2.9 4.85 0.862 0.854 0.695 0.679 0.406 0.104 0.167 5.53 2.
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L4970A 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. Specification mentioned in this publication are subject to change without notice.
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