SGS Thomson Microelectronics L4962A, L4962EH-A, L4962E-A Datasheet



1.5APOWER SWITCHING REGULATOR

1.5AOUTPUTCURRENT

5.1V TO40V OUTPUTVOLTAGE RANGE
PRECISE(±2%) ON-CHIPREFERENCE
HIGH SWITCHING FREQUENCY
VERYHIGH EFFICIENCY (UP TO 90%)
VERYFEW EXTERNALCOMPONENTS
SOFT START
INTERNALLIMITINGCURRENT
THERMALSHUTDOWN

DESCRIPTION

TheL4962 is a monolithicpower switching regula­tor delivering1.5Aat a voltage variable from 5V to
40V in step down configuration.

Featuresofthe device includecurrentlimiting,soft
start,thermal protectionand 0 to 100% dutycycle
for continuousoperatingmode.

L4962

POWERDIP

(12 + 2 + 2)

ORDERING NUMBERS

: L4962/A(12 + 2 + 2 Powerdip)

L4962E/A (Heptawatt
L4962EH/A (Horizontal

TheL4962ismountedin a16-leadPowerdipplastic
packageand Heptawattpackageand requiresvery
few externalcomponents.

Efficient operation at switching frequencies up to
150KHz allows a reduction in the size and cost of
external filtercomponents.

HEPTAWATT

Vertical)

Heptawatt)

BLOCKDIAGRAM

June 2000

Pin X = Powerdip
Pin (X) = Heptawatt

1/16

L4962

ABSOLUTEMAXIMUM RATINGS

Symbol Parameter Value Unit

Input voltage 50 V

7

Input to output voltage difference 50 V
Negative output DC voltage -1 V

2

V

7-V2

V

V

Output peakvoltage at t = 0.1µs; f= 100KHz -5 V

V

11,V15

V

P

T

j,Tstg

I
I

Voltageat pin11,15 5.5 V
Voltageat pin10 7 V

10

Pin 11 sink current 1 mA

11

Pin 14 source current 20 mA

14

Power dissipationat T

tot

Junction and storage temperature -40 to150

PIN CONNECTION (Top view)

C (Powerdip)

≤90°

pins

T

≤ 90°C (Heptawatt)

case

4.3
15

W
W

C

°

THERMALDATA

Symbol Parameter Heptawatt Powerdip

R

thj-case

R

thj-pins

R

thj-amb

* Obtained with the GND pins soldered to printed circuit with minimized copperarea.

Thermal resistance junction-case max 4°C/W ­Thermal resistance junction-pins max - 14°C/W
Thermal resistance junction-ambient max 50°C/W 80°C/W*

PIN FUNCTIONS

HEPTAWATT POWERDIP NAME

1 7 SUPPLYVOLTAGE Unregulatedvoltage input. Aninternalregulatorpowers

the internal logic.

2 10 FEEDBACK INPUT Thefeedback terminal of theregulation loop.Theoutput

is connected directly to thisterminal for 5.1V operation;
it is connected via a divider for higher voltages.

3 11 FREQUENCY

COMPENSATION

A series RC network connected between this terminal
and ground determines the regulation loop gain
characteristics.

2/16

FUNCTION

PIN FUNCTIONS (cont’d)

L4962

HEPTAWATT POWERDIP NAME

FUNCTION

4 4, 5, 12, 13 GROUND Common ground terminal.

5 14 OSCILLATOR A parallel RC network connected to this terminal

determines the switching frequency. This pin must be
connected to pin 7 input when the internal oscillator is
used.

6 15 SOFT START Soft start time constant. A capacitor is connected

between this terminaland ground to definethe softstart
time constant. This capacitor also determines the
average short circuit output current.

7 2 OUTPUT Regulator output.

1, 3, 6,

N.C.

8, 9, 16

ELECTRICAL CHARACTERISTICS

(Refer to the test circuit, T

=25°C, Vi= 35V, unless otherwise

j

specified)

Symbol Parameter Test Conditions Min. Typ. Max. Unit

DYNAMICCHARACTERISTICS

V

Output voltage range Vi= 46V Io=1A V

o

V

Input voltage range Vo=V

i

∆ V
∆

V

Line regulation Vi= 10V to 40V Vo=V

o

V

Load regulation Vo=V

o

Internal reference voltage

ref

(pin 10)

V

∆

∆

I

I

Average temperature

ref

coefficient of refer. voltage

T

V

Dropout voltage Io= 1.5A 1.5 2 V

d

Maximum operatingload

om

current

I

Current limiting threshold

2L

(pin 2)
Input average current Vi= 46V; outputshort-circuit 15 30 mA

SH

Efficiency f = 100KHz V

η

SVR Supply voltage ripple

rejection

ref

to 36V Io= 1.5A 9 46 V

ref

=1A 15 50 mV

refIo

ref

Io= 0.5A to 1.5A 8 20 mV

40 V

Vi= 9V to 46V Io= 1A 5 5.1 5.2 V

T

=0°C to125°C

j

=1A

I

o

Vi= 9V to 46V
V

o=Vref

to 36V

1.5 A

Vi= 9V to 46V
V

I

o

∆

fripple

V

to 36V

o=Vref

o=Vref

=1A Vo= 12V 80 %

V

=2V

i

rms

50 56 dB

= 100Hz

o=Vref

Io = 1A

0.4 mV/°C

2 3.3 A

70 %

3/16

L4962

ELECTRICAL CHARACTERISTICS

(continued)

Symbol Parameter Test Conditions Min. Typ. Max. Unit

DYNAMICCHARACTERISTICS

(cont’d)

f Switching frequency 85 100 115 KHz

f

∆

Voltagestability of

∆ V

∆

f

switching frequency

i

∆ f

Temperature stabilityof
switching frequency

T

j

Maximum operating

max

Vi= 9V to 46V 0.5 %

Tj=0°C to 125°C1%

Vo=V

ref

Io= 1A 120 150 KHz

switching frequency

T

Thermal shutdown

sd

150 °C

junction temperature

DC CHARACTERISTICS

I

Quiescent draincurrent 100% duty cycle

7Q

pins 2 and 14 open

V

= 46V

i

0% dutycycle 15 20 mA

30 40 mA

-I

Output leakagecurrent 0% duty cycle 1 mA

2L

SOFT START

I

15SO

I

Source current 100 140 180
Sink current 50 70 120 µA

15SI

ERRORAMPLIFIER

V
V
I

-I

High level output voltage V10= 4.7V I11= 100µA 3.5 V

11H

Low level output voltage V10= 5.3V I11= 100µA 0.5 V

11L

Sink output current V10= 5.3V 100 150

11SI

Source outputcurrent V10= 4.7V 100 150 µA

11SO

I

Input bias current V10= 5.2V 2 10

10

DC open loop gain V11=1Vto3V 46 55 dB

G

v

OSCILLATOR

-I

Oscillator source current 5 mA

14

A

µ

A

µ

A

µ

4/16

L4962

CIRCUITOPERATION

(refertothe blockdiagram)

TheL4962is amonolithicstepdownswitchingregu­latorprovidingoutputvoltagesfrom5.1Vto40Vand
delivering 1.5A.

The regulationloop consists of a sawtoothoscilla­tor, error amplifier, comparator and the output
stage.An errorsignalisproducedbycomparingthe
output voltage with a precise 5.1V on-chip refer­ence (zener zaptrimmedto±2%).

Thiserrorsignalis thencomparedwiththesawtooth
signal to generate the fixed frequencypulse width
modulated pulseswhich drivethe output stage.

The gain andfrequencystabilityof the loop can be
adjusted by an external RC network connectedto
pin 11. Closing the loop directly gives an output
voltage of 5.1V. Higher voltages are obtained by
insertinga voltagedivider.

Output overcurrentsat switchon are prevented by
the softstart function.The erroramplifieroutput is
initially clamped by the external capacitor C

and

ss

Figure1. Softstart waveforms

allowedtorise,linearly,asthiscapacitoris charged
by aconstantcurrentsource.Outputoverloadpro­tection is provided in the form of a current limiter.
The load current is sensed by an internal metal
resistorconnectedtoa comparator.When the load
currentexceedsapresetthresholdthis comparator
sets a flipflop whichdisables the output stage and
dischargesthe soft start capacitor.Asecondcom­parator resets the flipflopwhen thevoltageacross
the soft start capacitorhas fallento 0.4V.

The output stage is thusre-enabledandthe output
voltagerisesunder controlof the soft start network.
If the overload condition is still present the limiter
will trigger again when the threshold current is
reached.Theaverageshortcircuitcurrentislimited
to a safevalueby the dead timeintroduced by the
soft start network. The thermaloverload circuit dis­ables circuit operation when the junctiontempera­ture reaches about 150°C and has hysteresis to
preventunstable conditions.

Figure2. Currentlimiterwaveforms

5/16