SGS Thomson Microelectronics L4904A Datasheet



DUAL5V REGULATOR WITH RESET

.

OUTPUTCURRENTS : I01=50mA

I

=100mA

02

.

FIXEDPRECISIONOUTPUTVOLTAGE

±

5V

2%

.

RESETFUNCTION CONTROLLED BY INPUT
VOLTAGEAND OUTPUT 1 VOLTAGE

.

RESET FUNCTION EXTERNALLY PRO­GRAMMABLETIMING

.

RESETOUTPUT LEVELRELATEDTO
OUTPUT2

.

OUTPUT 2 INTERNALLY SWITCHED WITH
ACTIVEDISCHARGING

.

LOW LEAKAGE CURRENT, LESS THAN 1µA
ATOUTPUT 1

.

LOWQUIESCENTCURRENT (Input 1)

.

INPUT OVERVOLTAGE PROTECTION UP TO
60V

.

RESETOUTPUT NORMALLY HIGH

.

OUTPUTTRANSISTORSSOAPROTECTION

.

SHORT CIRCUIT AND THERMAL OVER­LOADPROTECTION

Minidip

ORDERING NUMBER :

L4904A

L4904A

DESCRIPTION

The L4904A is a monolithic low drop dual 5V
regulatordesignedmainlyforsupplyingmicroproc­essorsystems.

Resetand data savefunctionsduring switchon/off
canbe realized.

PIN CONNECTION

June 2000

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L4904A

PIN FUNCTIONS

N°

1 Input 1 Low Quiescent Current 50mA Regulator Input.
2 Input 2 100mA Regulator Input.
3 Timing

4 GND Common Ground.
5 N.C. Not connected.
6 Reset

7 Output 2 5V – 100mA Regulator Output. Enabled if V
8 Output 1 5V – 50mA regulator output with low leakage in switch-OFF condition.

BLOCKDIAGRAM

Name Function

If Reg. 2 is switching-ON the delay capacitor is charged with a 10µA constant current. When

Capacitor

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

When pin 3reaches 5V the reset output is switchedhigh.

Output

Therefore t

the C

capacitor is discharged.

o2

RD=Ct

5V

(

); tRD(ms) = Ct(nF).

10µA

1>VRTand V

o

IN 2>VIT

. If Reg. 2 is switched-OFF

SCHEMATIC DIAGRAM

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ABSOLUTEMAXIMUM RATINGS

Symbol Parameter Value Unit

V

IN

I

o

P

tot

T

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

Output Current Internally Limited
Power Dissipation at T
Storage and Junction Temperature – 40 to 150

j

amb

=50°C

24
60

1W

THERMALDATA

Symbol Parameter Value Unit

R

th j-amb

Thermal ResistanceJunction-ambient Max 100

L4904A

V
V

°C

°C/W

ELECTRICAL CHARACTERISTICS

(V

IN

= 14.4V,T

=25oC unlessotherwise specified)

amb

Symbol Parameter Test Conditions Min. Typ. Max. Unit

V

DC Operating Input Voltage 20 V

i

V

Output Voltage1

01

V
V

V

V

∆V
∆
∆
∆

Output Voltage2 HIGH

02 H

Output Voltage2 LOW I02= – 5mA 0.1 V

02 L

I

Output Current 1 ∆

01

I

Leakage Output 1 Current

L01

I

Output Current 2 ∆

02

Output 1 Dropout Voltage (*) I01= 10mA

I01

V

Input Threshold Voltage V01+ 1.2 6.4 V01+ 1.7 V

IT

Input Threshold Voltage Hyst. 250 mV

ITH

Line Regulation 7V < VIN< 18V, I01= 5mA 5 50 mV

01

Line Regulation 2 7V < VIN< 18V, I02= 5mA 5 50 mV

V

02

Load Regulation 1 VIN= 8V, 5mA < I01< 50mA 5 20 mV

V

01

Load Regulation 2 VIN= 8V, 5mA < I02< 100mA 10 50 mV

V

02

IQ Quiescent Current

Quiescent Current 1 6.3V < V

I

Q1

V

V

V

V

∆V

∆

S
S

* The dropout voltage is defined as the differencebetween the input and the output voltage when the output voltage is lowered of 25 mV under
constant output current condition.

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= – 5mA 0.25 0.4 V

RL

t

Reset Pulse Delay Ct= 10nF 3 11 ms

RD

t

Timing Capacitor Discharge

d

Time

01

Thermal Drift

T

∆

V

02

Thermal Drift – 20°C≤<0>T

∆T

Supply Voltage Rejection f = 100Hz, VR= 0.5V, Io= 50mA 50 84 dB

VR1

Supply Voltage Rejection f = 100Hz, VR= 0.5V, Io= 100mA 50 80 dB

VR2

R Load 1kΩ
R Load 1kΩ

= – 100mV

V

01

=0,V01≤ 3V

V

IN

= – 100mV

V

02

= 50mA

I

01

I

02=I01

0<V
7V < V

I

01

I

R

5mA

≤

< 13V

IN

< 13V

IN

< 13V, V

IN1

≤ 5mA, I02=0

= 500µA

IN2

=0

Ct= 10nF 20

–20°C≤<0>T

amb

amb

≤ 125°C

125°C

≤

4.95 5.05 5.15 V

V01–0.1 5 V

01

50 mA

1

100 mA

0.7

0.75

4.5

1.6

0.8

0.9

6.5

3.5

0.6 0.9 mA

V

– 1 4.12 V

02

02

0.3

–0.8

0.3

– 0.8

V

µA

V
V

mA

V

µs

mV/°C

mV/°C

3/9

L4904A

TESTCIRCUIT

Figure1 : P.C.Board and ComponentsLayoutof the Test Circuit (1:1 scale)

APPLICATIONINFORMATION

Inpower suppliesfor µPsystems it is necessaryto
provide power continuously to avoid loss of infor­mationin memoriesand in time of dayclocks,or to
savedatawhen theprimarysupplyisremoved.The
L4904A makes it very easy to supply such equip­ments;itprovidestwo voltageregulators(booth5V
high precision) with separate inputs plus a reset
output forthe data savefunction.

CIRCUITOPERATION(see Figure 2)

After switch on Reg. 1 saturatesuntil V

rises to

01

the nominalvalue.
When the input 2 reaches V

higherthanV
the reset output (V
grammabletime T

V

andVRareswitchedtogetherat lowlevelwhen

02

theoutput 2 (V02) switcheson and

RT

) also goes high after a pro-

R

(timingcapacitor).

RD

and the output 1 is

IT

one of the followingconditionsoccurs :

- an input overvoltage

- an overloadon the output 1 (V

- a switchoff (V

IN<VIT-VITH

);

01<VRT

);

and they start againas before when the condition
is removed.

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

TheV

outputfeatures:

01

- 5 V internal reference without voltage divider
between the output and the error comparator;

- very low drop series regulator element utilizing
mirrors ;

permit high output impedance and then very low
leakagecurrent even in powerdown conditions.

Thisoutputmaythereforebeusedtosupplycircuits
continuously, such as volatile RAMs, allowing the
use of a back-up battery. The V

regulator also

01

featureslowconsumption(0.6 mAtyp.)to minimize
batterydrainin applicationswhere theV

regulator

1

is permanentlyconnectedto a battery supply.
TheV

outputcan supply other non essential5 V

02

circuits which may be powered down when the
systemis inactive,or that must be powered down
to prevent uncorrect operation for supply voltages
belowthe minimumvalue.

Theresetoutputcanbe usedas a”POWERDOWN
INTERRUPT”, permitting RAM access only in cor­rectpowerconditions,oras a”BACK-UPENABLE”
to transfer data into in a NV SHADOW MEMORY
when the supply is interrupted.

4/9

Figure2

L4904A

APPLICATIONSUGGESTIONS

Figure 3 shows an application circuit for a µP
system.

Reg.1 is permanently connected to a battery and
supplies a CMOS time-of-day clock and a CMOS
microcomputerchip with volatilememory.

Reg.2 maybe switched OFF when the system is
inactive.

Figure4 shows the L4904Awith a backup battery
onthe V

outputto maintaina CMOStime-of-day

01

Figure3

clock and a stand by type C-MOSµP. The reset
output makes surethat the RAM is forced into the
low consumption stand by state, so the access to
memory is inhibit and the back up battery voltage
cannotdrop so low that memory contents arecor­rupted.

Inthis casethe mainon-offswitchdisconnectsboth
regulatorsfrom the supply battery.

Application Circuits of a Microprocessor system
(Figure3) or with data savebattery (Figure4). The
reset output provide delayed rising front at the

5/9

L4904A

Figure4

6/9

L4904A

Figure5 : QuiescentCurrent (reg. 1) versus

Output Current

Figure7 : TotalQuiescentCurrent versus

Input Voltage

Figure6 : QuiescentCurrent (reg. 1 versus

Input Voltage

Figure8 : SupplyVoltage Rejection

Regulators1 and 2 versus Input
Ripple Frequence

7/9

L4904A

DIM.

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

A 3.32 0.131

a1 0.51 0.020

B 1.15 1.65 0.045 0.065

b 0.356 0.55 0.014 0.022

b1 0.204 0.304 0.008 0.012

D 10.92 0.430
E 7.95 9.75 0.313 0.384

e 2.54 0.100
e3 7.62 0.300
e4 7.62 0.300

F 6.6 0.260

I 5.08 0.200
L 3.18 3.81 0.125 0.150
Z 1.52 0.060

mm inch

OUTLINE AND

MECHANICAL DATA

Minidip

8/9

L4904A

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mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information
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without express written approval of STMicroelectronics.

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