Datasheet L4902A Datasheet (SGS Thomson Microelectronics)



DUAL 5V REGULATOR WITH RESETAND DISABLE

.

DOUBLEBATTERYOPERATING

.

OUTPUTCURRENTS : I01=300 mA

= 300 mA

I

02

.

FIXED PRECISIONOUTPUT VOLTAGE
5V±

2

%

.

RESETFUNCTION CONTROLLED BY INPUT
VOLTAGEANDOUTPUT1 VOLTAGE

.

RESET FUNCTION EXTERNALLY PRO­GRAMMABLETIMING

.

RESET OUTPUT LEVEL RELATED TO OUT­PUT 2

.

OUTPUT 2 INTERNALLY SWITCHED WITH
ACTIVEDISCHARGING

.

OUTPUT2 DISABLELOGICALINPUT

.

LOW LEAKAGE CURRENT, LESS THAN 1µA
ATOUTPUT1

.

RESETOUTPUT NORMALLY HIGH

.

INPUT OVERVOLTAGE PROTECTION UP TO
60V

.

OUTPUTTRANSISTORS SOA PROTECTION

.

SHORT CIRCUIT AND THERMAL OVER­LOADPROTECTION

L4902A

HEPTAWATT

ORDERING NUMBER : L4902A

(Vertical)

DESCRIPTION

The L4902A is a monolithic low drop dual 5V
regulatordesignedmainlyfor supplying microproc­essorsystems.

Reset and data save functions and remoteswitch
on/offcontrol can be realized.

PIN CONNECTION

June 2000

1/9

L4902A

PIN FUNCTIONS

N°

1 Input 1 Regulators Common Input
2 Timing

3 Disable Input A high level (> V
4 GND Common Ground
5 Reset Output When pin 2 reaches 5V the reset output is switched high.

6 Output 2 5V – 300mA Regulator Output. Enabled if V
7 Output 1 5V – 300mA. Low leakage (in switch-OFF condition) output

BLOCKDIAGRAM

Name Function

If Reg. 2 is switched-ON thedelay capacitor is charged with a5µA constant current. When

Capacitor

Reg. 2 is switched-OFF the delay capacitor is discharged.

) disable outputReg. 2.

DT

5V

(

Therefore t

RD=Ct

Reg. 2 is switched-OFF the C

);tRD(ms) = Ct(nF)

10µA

capacitor is discharged.

02

1>VRT. DISABLE INPUT < VDTand VIN>VIT.If

o

SCHEMATIC DIAGRAM

2/9

L4902A

ABSOLUTE MAXIMUMRATINGS

Symbol Parameter Value Unit

V

I

T

stg,Tj

IN

o

DC Input Voltage
Transient Input Overvoltage(t = 40ms)

Output Current Internally Limited
Storage and Junction Temperature – 40 to 150

THERMAL DATA

Symbol Parameter Value Unit

R

th j-case

Thermal Resistance Junction-case Max 4

28
60

V
V

°C

°C/W

ELECTRICAL CHARACTERISTICS

(V

IN

= 14.4V,T

=25oC unless otherwise specified))

amb

Symbol Parameter Test Conditions Min. Typ. Max. Unit

V

DC Operating Input Voltage 24 V

i

V

V

V

I

I

L01

I

V

V

V

∆V
∆V
∆V
∆V

V

V

V

V

t

V

∆V

∆

∆V

∆

SVR1 Supply Voltage Rejection f = 100Hz V

Output Voltage 1

01

Output Voltage 2 HIGH

02 H

Output Voltage 2 LOW I02= – 5mA 0.1 V

02 L

Output Current 1 max.

01

Leakage Output 1 Current
Output Current 2 max.

02

Output 1 Dropout Voltage (*) I01= 10mA

i01

Input Threshold Voltage V01+ 1.2 6.4 V01+ 1.7 V

IT

Input Threshold VoltageHyst. 250 mV

iTH

Line Regulation 1 7V < VIN< 24V,I01= 5mA 5 50 mV

01

Line Regulation 2 7V < VIN< 24V,I02= 5mA 5 50 mV

02

Load Regulation 1 5mA < I01< 300mA 40 80 mV

01

Load Regulation 2 5mA < I02< 300mA 50 80 mV

02

Quiescent Current

I

Q

Reset Threshold Voltage V02– 0.15 4.9 V02– 0.05 V

RT

Reset Threshold Hysteresis 30 50 80 mV

RTH

Reset Output Voltage HIGH

RH

Reset Output Voltage LOW IR= – 1mA 0.25 0.4 V

RL

Reset Pulse Delay Ct= 10nF 3 5 11 ms

RD

t

Timing Capacitor Discharge Time Ct= 10nF 20

d

V02Disable Threshold Voltage 1.25 2.4 V

DT

I

V02Disable Input Current

D

01

Thermal Drift

T

02

Thermal Drift

T

R Load 1k
R Load 1k

= – 100mV

∆V

01

=0,V01≤ 3V

V

IN

= – 100mV

∆V

02

= 100mA

I

01

= 300mA

I

01

I
0<V
7V < V
7V < V

I

V
V

01=I02

= 500µA

R

≤ 0.4V

D

≥ 2.4V

D

≤

< 13V

IN

< 13V V02LOW

IN

< 13V V02HIGH

IN

–20°C≤T

–20°C≤T

Io = 100mA

Ω 4.95 5.05 5.15 V
Ω V

–0.1 5 V

01

300 mA

300 mA

0.7

0.8

1.1

5mA

4.5

2.7

1.6

V

– 1 4.12 V

02

– 150

–30

amb

amb

R

≤125°C

≤125°C

= 0.5V

50 84 dB

0.3

– 0.8

0.3

– 0.8

1

0.8
1

1.4

6.5

4.5

3.5

01

V

µA

V
V
V

mA

02

V

µs

µA
µA

mV/°C

mV/°C

SVR2 Supply Voltage Rejection 50 80 dB

* The dropoutvoltage is defined as thedifference between theinput and the outputvoltage when theoutputvoltage is lowered of 25mV under
constant output current condition.

3/9

L4902A

TESTCIRCUIT

APPLICATIONINFORMATION

InpowersuppliesforµPsystemsit is necessaryto
provide power continuously to avoid loss of infor­mationinmemoriesandin timeof dayclocks,or to
savedatawhen theprimarysupplyisremoved.The
L4902A makes it very easy to supplysuch equip­ments;it providestwo voltage regulators (both 5V
high precision) with common inputs plus a reset
output for the data save function and a Reg. 2
disableinput.

CIRCUITOPERATION (see Figure 1)

After switch on Reg. 1 saturates until V

rises to

01

the nominal value.
When the input reaches V

higherthan V
the reset output (V

theoutput2 (V02) switcheson and

RT

) also goes high after a pro-

R

and the output 1 is

IT

Figure1

grammabletime T
V

andVRareswitchedtogetherat lowlevelwhen

02

(timingcapacitor).

RD

one of the followingconditionsoccurs :

- a high level( V

) is applied on pin 3 ;

DT

- an input overvoltage;

- an overload on the output 1 (V

- a switch off (V

INVIT-VITH

);

01VRT

);

and theystart again as beforewhen the condition
is removed.

An overload on output 2 does not switch Reg. 2,
and does not influenceReg.1.

TheV

outputfeatures:

01

- 5V internal referencewithout voltage divider be­tween the outputand theerror comparator

- very low drop series regulator element utilizing
current mirrors

permit high output impedance and then very low
leakagecurrent even in power down condition.

4/9

L4902A

Thisoutputmaythereforebeusedtosupplycircuits
continuously, such as volatile RAMs, allowing the
useof a back-upbattery.

TheV

output can supply othernon essential5 V

02

circuits which may be powered down when the
system is inactive, or that must be powereddown
to preventuncorrect operationfor supply voltages
belowthe minimumvalue.

Theresetoutputcanbeusedas a”POWERDOWN
INTERRUPT”, permitting RAM access only in cor­rectpowerconditions,orasa”BACK-UPENABLE”
to transfer data into in a NV SHADOW MEMORY

Figure2

when the supply is interrupted.
Thedisablefunctioncan be usedfor remoteon/off

controlof circuitsconnectedto theV

output.

02

APPLICATION SUGGESTIONS

Figure 2 illustrate how the L4902A’sdisable input
maybe used in a CMOSµComputerapplication.
TheV

regulator(lowconsumption)supplyperma-

01

nently a CMOS time of day clock and a CMOS
µcomputer chip with volatile memory. V

02

output,
supplyingnon-essentialcircuits,is turned OFFun­dercontrol of a

µPunit.

Figure3 :

P.C.Board Component Layoutof Figure 2

5/9

L4902A

Configurations of this type are used in products
where the OFF switch is part of a keyboard
scanned by a micro which operates continuously
evenin the OFF state.

Anotherapplication for the L4902A is supplying a
shadow-rammicrocomputer chip (SGS M38SH72
forexample)where afastNV memoryisbackedup
onchipbyaEEPROMwhena lowlevelonthereset
output occurs.

By adding two CMOS-SCHMIDT-TRIGGER and
few external components, also a watch dog func-

Figure4

tionmaybe realized(see Figure5). During normal
operation the microsystem supplies a periodical
pulsewaveform;ifananomalousconditionoccours
(intheprogramorinthesystem),thepulseswillbe
absentand the disableinput will be activatedafter
a settlingtime determinedby R1 C1.In this condi­tion all the circuitry connected to V

will be dis-

02

abled,the systemwillbe restartedwith a newreset
front.

Thedisableof V

preventspuriousoperationdur-

02

ing microprocessormalfunctioning.

Figure5

6/9

L4902A

Figure6 : QuiescentCurrent versusOutput

ICurrent

Figure8 : Supply Voltage Rejection

Regulators1 and 2 versus Input Rip­ple Frequence

Figure7 : QuiescentCurrent versusInput Voltage

7/9

L4902A

DIM.

MIN. TYP. MAX. MIN. TYP. MAX.

A 4.8 0.189
C 1.37 0.054
D 2.4 2.8 0.094 0.110

D1 1.2 1.35 0.047 0.053

E 0.35 0.55 0.014 0.022

E1 0.7 0.97 0.028 0.038

F 0.6 0.8 0.024 0.031

F1 0.9 0.035

G 2.34 2.54 2.74 0.095 0.100 0.105
G1 4.88 5.08 5.28 0.193 0.200 0.205
G2 7.42 7.62 7.82 0.295 0.300 0.307
H2 10.4 0.409
H3 10.05 10.4 0.396 0.409

L 16.7 16.9 17.1 0.657 0.668 0.673
L1 14.92
L2 21.24 21.54 21.84 0.386 0.848 0.860
L3 22.27 22.52 22.77 0.877 0.891 0.896
L4 1.29
L5 2.6 2.8 3 0.102 0.110 0.118
L6 15.1 15.5 15.8 0.594 0.610 0.622
L7 6 6.35 6.6 0.236 0.250
L9 0.2 0.008

M 2.55 2.8 3.05 0.100 0.110 0.120

M1 4.83 5.08 5.33 0.190 0.200 0.210

V4 40° (typ.)

Dia 3.65 3.85 0.144 0.152

mm inch

0.587

0.051

0.260

OUTLINE AND

MECHANICAL DATA

Heptawatt V

H3

L

VV

E

L1

M1

A

C

D

M

D1

H2

V4

L9

H1

L5

Dia.

L2
L3

F

E1

E

GG1G2

F

L7

L4

L6

F1H2

HEPTAMEC

8/9

L4902A

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 infringementof patents or other rights of third partieswhich 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. This publication supersedes and replaces all information
previouslysupplied.STMicroelectronicsproducts arenot authorizedforuse ascriticalcomponents inlife supportdevices orsystems
without express written approval of STMicroelectronics.

Australia - Brazil - China - Finland- France - Germany - Hong Kong - India - Italy - Japan - Malaysia - Malta - Morocco -

The ST logo is a registered trademark of STMicroelectronics

 2000 STMicroelectronics – Printed in Italy – All Rights Reserved

STMicroelectronics GROUP OF COMPANIES

Singapore- Spain - Sweden - Switzerland - UnitedKingdom - U.S.A.

http://www.st.com

9/9