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L4976D013TR中文资料

April 2007Rev 71/17

L4976

1A step down switching regulator

Features

■Up to 1A step down converter ■Operating input voltage from 8v to 55v ■Precise 5.1V reference voltage

■Output voltage adjustable from 0.5V to 50V ■Switching frequency adjustable up to 300kHz ■Voltage feedforward ■Zero load current operation

■Internal current limiting (pulse-bypulse ■and hiccup mode)

■Protection against feedback disconnection ■

Thermal shutdown

Description

The L4976 is a step down monolithic power switching regulator delivering 1A at a voltage between 3.3V and 50V (selected by a simple external divider). Realized in BCD mixed

technology, the device uses an internal power D-MOS transistor (with a typical R ds(ON) of 0.25?) to obtain very high efficency and high switching speed. A switching frequency up to 300KHz is achievable (the maximum power dissipation of the packages must be observed). A wide input voltage range between 8V to 55V and output voltages regulated from 3.3V to 40V cover the majority of today’s applications. Features of this new generations of DC-DC converter include pulse-by-pulse current limit, hiccup mode for short circuit protection, voltage feedforward regulation, protection against feedback loop disconnection and thermal shutdown. The device is available in plastic dual in line, MINIDIP 8 for standard assembly, and SO16W for SMD assembly.

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Contents L4976

Contents

1Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.1Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.2Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.1Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.2Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.3Operating temperature rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5Typical charcteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 7Order code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 8Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

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L4976Block diagram

3/17

1 Block diagram

Pin settings L4976

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2 Pin settings

2.1 Pin connection

2.2 Pin description

Table 1. Pin description

N° Pin

Name

Description

DIP8

SO16W (1)

1.Pins 1, 7, 8, 9, 10, 15 and 16 are not internally, electrically connected to the die.

1 2 GND Ground 2

VREF

5.1V Reference voltage with 20mA current capability.

3 4 OSC

An external resistor connected between the unregulated

input voltage and this pin and a capacitor connected

from this pin to ground fix the switching frequency. (Line feed forward is automatically obtained) 4 5, 6 OUT Stepdown regulator output. 5

VCC

Unregulated DC input voltage.

6 12 BOOT

A capacitor connected between this pin and OUT allows

to drive the internal VDMOS. 7

COMP

E/A output to be used for frequency compensation.

8 14 FB Stepdown feedback input. Connecting directly to this pin

results in an output voltage of 3.3V . An external resistive

divider is required for higher output voltages.

L4976Electrical data

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3 Electrical data

3.1 Maximum ratings

3.2 Thermal data

3.3 Operating temperature rating

Table 2. Absolute maximum ratings

Symbol

Parameter Value Unit DIP8

S016W V5 V11Input voltage

58 V V4 V5, V6Output DC voltage

-1 V Output peak voltage at t = 0.1μs, f = 200kHz -5 V I4 I5, I6

Maximum output current

internal limit

V6-V5 V12-V11 14 V V6 V12Bootstrap voltage

V7 V13Analogs input voltage (V CC = 24V) 12 V

V14

(V CC = 20V)

V -0.3 V P TOT Power dissipation a T A ≤ 60°C DIP8 1 W SO16

0.8 W T J ,T STG

Junction and storage temperature

-40 to 150

°C

Table 3. Thermal data

Symbol Parameter

DIP8

S016W Unit R thJA

Maximum thermal resistance junction-ambient

90 (1)

1.Package mounted on board

110 (1)

°C/W

Table 4. Operating temperature rating

Symbol Parameter

Value

Unit T J

Junction temperature range

-40 to 150

°C

4 Electrical

characteristics

Table 5. Electrical characteristics

(T J = 25°C, C OSC = 2.7nF, R OSC = 20k?, V CC = 24V, unless otherwise specified.) Symbol Parameter Test condition Min Typ Max Unit Dynamic characteristic

V I Operating input voltage range V

O = 3.3 to 50V; I O = 1A

(1)855V

V O Output voltage I O = 0.5A 3.33 3.36 3.39V I O = 0.2 to 1A 3.292 3.36 3.427V V CC = 8 to 55V (1) 3.22 3.36 3.5V

Vd Dropout voltage

V CC = 10V; I O = 1A0.290.367V

(1)0.587V

I l Maximum limiting current V CC = 8 to 55V (1) 1.52 2.5A

Efficiency V O = 3.3V; I O = 1A85% f s Switching frequency(1)90100110KHz

SVRR Supply voltage ripple rejection V I = V CC + 2V RMS; V O = V ref;

I O = 1.A; f ripple = 100Hz

60dB

Voltage stability of switching

frequency

V CC = 8 to 55V36%

Temp. stability of switching

frequency

T J = 0 to 125°C4% Reference section

Reference voltage 5.0 5.1 5.2V

I ref = 0 to 10mA; (1) 4.950 5.1 5.250V

V CC = 8 to 55V

Line regulation I ref = 0mA;510

mV V CC = 8 to 55V

Load regulation V ref = 0 to 5mA;210mV V CC = 0 to 20mA625mV

Short circuit current3065100mA

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7/17

Symbol

Parameter Test condition Min Typ Max Unit

DC Characteristics

I qop Total operating quiescent current 46mA I q

Quiescent current

Duty Cycle = 0; V FB = 3.8V

2.5

3.5

Error Amplifier

V FB Voltage feedback input 3.33

3.36 3.39V R L

Line regulation V CC = 8 to 55V 510

mV Ref. voltage stability vs temperature

(1)

0.4

mV/°C V oH High level output voltage V FB = 2.5V 10.3

V oL Low level output voltage V FB = 3.8V

0.65

V I O source Source output current V comp = 6V; V FB = 2.5V 180220μA I O sink

Sink output current V comp = 6V; V FB = 3.8V

200300μA I b

Source bias current

μA SVRR E/A

Supply voltage ripple rejection V comp = Vfb; V CC = 8 to 55V 6080dB DC open loop gain

R L = ∞

57dB gm Transconductance

I comp = -0.1 to 0.1mA V comp = 6V

2.5

Oscillator section

Ramp valley 0.78

0.850.92V Ramp peak V CC = 8V 2 2.15 2.3V V CC = 55V

99.610.2

V Maximum duty cycle 95

Maximum frequency

Duty cycle = 0%

R osc = 13kW, C osc = 820pF

300kHz

1.Specification refered to Tj from 0 to 125°C

Table 5. Electrical characteristics (continued)

(T J = 25°C, C OSC = 2.7nF, R OSC = 20k ?, V CC = 24V, unless otherwise specified.)

charcteristics

5 Typical

Figure 5.Line regulation

Figure 4.Quiescent drain current vs.

Figure 6.Quiescent current vs. junction

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Figure 8.Load regulation Figure 9.Switching frequency vs. input

Figure 11.Efficiency vs. output current

Figure 10.Switching frequency vs.

Figure 12.Dropout voltage between pin 5

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Figure 18.Efficiency vs. V CC Figure 19.Pulse by pulse limiting

current vs. junction

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Figure 22.Line transient

Figure 23.Open loop frequency and

phase of error amplifier

-150-100-50GAIN (dB)0

Phase

04590

135

D97IN787

GAIN

Phase

6 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: https://www.wendangku.net/doc/6b8612403.html,

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L4976Order code

15/17

7 Order code

Table 6. Order code

Part number

Package Packaging L4976DIP8Tube L4976D SO16W Tube L4976D013TR

SO16W

T ape and reel

Revision history L4976

16/17

8 Revision history

Table 7. Revision history

Date Revision

Changes

5-Aug-20016First Issue

3-Apr-2007

Document reformatted, updated dropout voltage values in T able 5 on

page 6

L4976

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