L4901 Fast Delivery |IC PHOENIX CO.,LIMITED

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L4901
DUAL 5V REGULATOR WITH RESET
L4901A
DUAL 5V REGULA TOR WITH RESET
June 2000
PIN CONNECTION
HEPTAWATT (Vertical)
(Plastic Package)
ORDERING NUMBER: L4901A OUTPUT CURRENTS:I01= 400mA
I02= 400mA. FIXEDPRECISIONOUTPUT VOLT AGE± 2%. RESET FUNCTION CONTROLLED BY INPUT
VOLT AGE AND OUTPUT1 VOLTAGE. RESET FUNCTION EXTERNALLY PRO-
GRAMMABLETIMING. RESET OUTPUT LEVEL RELATED TO OUT-
PUT2. OUTPUT2 INTERNALLY SWITCHED WITH
ACTIVE DISCHARGING. LOW LEAKAGE CURRENT, LESS THAN 1μA
ATOUTPUT1. LOW QUIESCENT CURRENT (Input1). INPUT OVERVOLT AGE PROTECTION UP TO
60V. RESET OUTPUT HIGH. OUTPUT TRANSISTORS SOA PROTECTION. SHORT CIRCUIT AND THERMAL OVER-
LOAD PROTECTION
DESCRIPTION
The L4901Aisa monolithic low drop dual 5V
regulator designedmainly forsupplying microproc-
essor systems.
Reset and data savefunctionsduring switch on/off
canbe realized.
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BLOCK DIAGRAM
SCHEMATIC DIAGRAM
PIN DESCRIPTION Name Function Input1 Low QuiescentCurrent 400mA Regulator Input. Input2 400mA regulator input. Timing
Capacitor Reg.2is switched-ONthe delay capacitoris charged witha 10μA constant current. When Reg.is switched-OFFthe delay capacitoris decharged. GND Common Ground. Reset
Output
Whenpin3 reaches5V thereset outputis switched high.
ThereforetRD =Ct( 5V
10μA); tRD (ms)=Ct (nF) Output2 5V– 400mA Regulator Output. EnabledifVo 1> VRT andVIN2 >VIT.If Reg.2is switched-OFF
the C02 capacitoris discharged. Output1 5V– 400mA regulator output with Low leakage(in switch-OFF condition).
L4901A
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ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Value Unit
VIN DC Input Voltage
Transient Input Overvoltage(t= 40ms) Output Current Internally Limited Storage and Junction Temperature –40to 150 °C
THERMAL DATA
Symbol Parameter Value Unit
Rth(j-c) Thermal Resistance Junction-case Max. 4 °C/W
ELECTRICAL CHARACTERISTICS (VIN= 14, 4V, Tamb =25°C unless otherwise specified)
Symbol Parameter Test Conditions Min. Typ. Max. Unit DC Operating Input Voltage 20 V
V01 Output Voltage1 R Load 1kΩ 4.95 5.05 5.15 V
V02H Output Voltage2 HIGH R Load 1kΩ V01 –0.1 5 V01 V
V02L Output Voltage2 LOW I02=– 5mA 0.1 V
I01 Output Current1 ΔV01=– 100mV 400 mA
IL01 Leakage Output1 Current VIN =0, V01≤3V 1 μA
I02 Output Current2 ΔV02=– 100mV 400 mA
VI01 Output1 Dropout Voltage(*) I01= 10mA
I01= 100mA
I01= 300mA
VIT Input Threshold Voltage V01+1.2 6.4 V01+1.7 V
VITH Input Threshold Voltage Hyst. 250 mV
ΔV01 Line Regulation1 7VΔV02 Line Regulation2 7VΔV01 Load Regulation1 5mAΔV02 Load Regulation2 5mAIQ1 Quiescent Current1 I01≤ 5mA,I02 =0, VIN2 =0
6.3V0.6 0.9 mA
VRT Reset Threshold Voltage V02– 0.15 4.9 V02 –0.05 V
VRTH Reset Threshold Hysteresis 30 50 80 mV
VRH Reset Output Voltage HIGH IR= 500μA V02–1 4.12 V02 V
VRL Reset Output Voltage LOW IR= –<0>5mA 0.25 0.4 V
tRD Reset Pulse Delay Ct= 10nF 3 5 11 ms TimingCapacitor Discharge Time Ct= 10nF 20 μs
ΔV01 Thermal Drift –20°C≤ Tamb≤ 125°C 0.3–
0.8 mV/°C
ΔV02 Thermal Drift –20°C≤ Tamb≤ 125°C 0.3–
0.8 mV/°C
SVR1 Supply Voltage Rejection f= 100Hz,VR= 0.5V= 100mA 84 dB
SVR2 Supply Voltage Rejection 50 80 dB The dropoutvoltageis definedas thedifferencebetween theinputandthe outputvoltage whenthe outputvoltageis loweredof25mV under
constant output currentcondition.
L4901A
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TEST CIRCUIT
APPLICA TION INFORMATION power suppliesforμP systemsitis necessaryto
provide power continuouslyto avoid lossof infor-
mationin memories andin timeof day clocks,orto
savedatawhen theprimarysupplyis removed.The
L4901A makesit very easyto supply such equip-
ments;it providestwo voltage regulators(both5V
high precision) with separate inputs plusa reset
output forthe data save function.
CIRCUIT OPERATION (see Figure1)
After switchon Reg.1 saturates until V01 risesto
the nominal value.
When the input2 reaches VIT and the output1is
higherthan VRT the output2 (V02) switcheson and
the reset output (VR) also goes high aftera pro-
grammable time TRD (timing capacitor).
V02 andVR areswitched togetherat low level when
oneof the following conditions occurs:an input overvoltagean overloadon the output1 (V01 and they start againas before when the condition removed. overloadon output2 does not switch Reg.2,
and does not influence Reg.1.
TheV01 output features:5V internal reference without voltage divider
between the output and the error comparator; very low drop series regulator element utilizing
current mirrors;
permit high output impedance and then very low
leakage current error evenin power down condi-
Figure1
L4901A
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tion.
Thisoutputmaythereforebe usedto supplycircuits
continuously, suchas volatile RAMs, allowing the
useofa back-up battery. The V01 regulator also
featureslow consumption(0.6 mA typ.)to minimize
battery drainin applicationswhere theV1 regulator permanentlyconnectedtoa battery supply.
The V02 output can supply other non essential5V
circuits which may be powered down when the
systemis inactive,or that mustbe powered down prevent uncorrect operationfor supply voltages
below the minimum value.
Theresetoutputcanbe usedasa ”POWERDOWN
INTERRUPT”, permitting RAM access onlyin cor-
rect powerconditions,orasa ”BACK-UPENABLE” transfer data intoina NV SHADOW MEMORY
when the supplyis interrupted.
APPLICATIONS SUGGESTIONS
Figure2 shows an application circuit fora μP
system typically usedin trip computersorin car
radios with programmable tuning.
Reg.1is permanently connectedtoa battery and
suppliesa CMOS time-of-day clock anda CMOS
microcomputer chip with volatile memory.
Reg.2 maybe switched OFF when the systemis
Figure2
Figure3: P.C. Board Component Layoutof Figure2.
L4901A
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inactive.
Figure4 shows the L4901A witha backup battery the V01 outputto maintaina CMOStime-of-day
clock anda standby type N-MOS μP. The reset
output makessure that the RAMis forced into the
low consumption standby state,so the accessto
memoryis inhibit and the backup battery voltage
cannot dropso low that memory contents are cor-
rupted.
Inthis casethe mainon-offswitch disconnectsboth
regulators from the supply battery.
The L4901Ais also ideal for microcomputer sys-
tems using batterybackup CMOS staticRAMs.As
shownin Figure5 the reset outputis used bothto
Figure4
Figure5
L4901A
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Partno	Mfg	Dc	Qty	Available	Descript
L4901	SGS-THOMSON	N/a	1800	avai	DUAL 5V REGULATOR WITH RESET