UNISEM US431LCZ, US431LCS, US431LCL, US431ALCZ, US431ALCS Datasheet
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US431L/431AL
LOW -VOLTAGE ADJUSTABLE
PRECISION SHUNT REGULATOR
PRELIMINARY DATASHEET
FEATURESFEATURES
SOT23-5 package
0.5% Voltage Reference Initial Accuracy
(US431AL)
Low Operational Cathode Current
(80 uA max)
Unconditionally Stable with only 1uF
Adjustable Output from 1.24V to 6V
0.25Ω Typical Output Impedance
Pin to Pin Compatible with TLV431
APPLICATIONSAPPLICATIONS
Precision Voltage Reference
Linear Regulator Controller
Secondary Side Controller for the Low Voltage
Power Supply Applications
TYPICAL APPLICATIONTYPICAL APPLICATION
V
IN
DESCRIPTIONDESCRIPTION
The US431L product is a 3 terminal adjustable shunt
regulator that can also be used as a precision voltage
reference. Its output voltage may be set to any value
between Vref(1.24V) and 6V with two external resistors
as shown in the typical application circuit. Other applications of this device include the use as a merged amplifier and reference in applications such as Linear regulator or as the secondary side controller in low voltage
power supply applications. The US431L only requires
80uA maximum quiescent current before regulating,
making it ideal as a voltage reference for battery type
applications.
R
B
V
O
R1
Co
Vo Vref
= × +
US431
R2
R
1
1
R
2
Typical application of the US431L as a shunt regulator / voltage reference.
431app1-1.0
PACKAGE ORDER INFORMATIONPACKAGE ORDER INFORMATION
Ta (°C) 5 LEAD 3 PIN PLASTIC 8 PIN PLASTIC
SOT23-5 TO-92 SOIC
0 TO 70 US431LCL US431LCZ US431LCS
0 TO 70 US431ALCL US431ALCZ US431ALCS
Rev. 1.2
5/11/98
2-1
US431L/431AL
ABSOLUTE MAXIMUM RATINGSABSOLUTE MAXIMUM RATINGS
Input Voltage (Vin) ............................................................. 7V
Continuous Cathode Current Range ......................................... -20 mA to +20 mA
Reference Current Range ...................................................... -0.05 mA to 3 mA
Storage Temperature Range ................................ -65°C TO 150°C
Operating Junction Temperature Range ...................... 0°C TO 150°C
PACKAGE INFORMATIONPACKAGE INFORMATION
5 PIN SOT 23 (L) 3 PIN PLASTIC TO-92 (Z) 8 PIN PLASTIC SOIC (S)
BOTTOM VIEW
1
2
3
Ref
Anode
Cathode
NC
NC
Cathode
TOP VIEW
1
2
3
5
4
Anode
Ref
θJA = 450°C/W θJA = 162°C/W θJA=160°C/W
ELECTRICAL SPECIFICATIONSELECTRICAL SPECIFICATIONS
Unless otherwise specified ,these specifications apply over Ta=0 to 70 °C, CO =1uF. Typical values refer to
Ta=25 °C.Low duty cycle pulse testing are used which keeps junction and case temperatures equal to the
ambient temperature.
PARAMETER SYM TEST CONDITION MIN TYP MAX UNITS
Reference Voltage Vref IK=10mA,VKA=Vref,Ta=25°C 1.228 1.240 1.252 V
US431L IK=10mA,VKA=Vref 1.221 1.240 1.259
Reference Voltage Vref IK=10mA,VKA=Vref,Ta=25°C 1.234 1.240 1.246 V
US431AL IK=10mA,VKA=Vref 1.228 1.240 1.252
Vref deviation over full Vref(dev) VKA=Vref, IK=10mA 4 12 mV
temperature range Note 1
Ratio of Vref change to dVref/dVKA IK=10mA , dVKA=Vref to 6 V -1.5 -2.7 mV/V
Cathode voltage change
Reference pin current IK=10mA , R1=10kΩ , R2=open 0.15 0.5 uA
Iref deviation over full Iref(dev) IK=10mA , R1=10kΩ , R2=open 0.05 0.3 uA
temperature range Note 1
Minimum cathode current IK(min) VKA=Vref 55 80 uA
Off state cathode current Ioff VKA=6V , Vref=0V 0.001 0.1 uA
Dynamic impedance Zka0 VKA=Vref, f<1 kHz, 0.25 0.4 Ω
IK=0.1 to 15 mA , Note 2
Note 1 : The deviation parameters, Vref(dev) and Iref(dev) are
defined as the differences between the maximum and the minimum
values obtained over the rated temperature range. The average full
range temperature coeficient of the reference input voltage is defined as :
Vref dev
Vref C
Vref
=
Vref
unit is ppm/ C
T
A
Vref can b
e positive or negative depending on whether
α
Where:
α
∆
is the rated operating free air temperature
of the device.
α
minimum Vref or maximum Vref, respectively occurs at the
lower temperature.
( )
( )25
6
×
10
°
T
A
∆
°
Note 2 :
Thedynamic
Zka0
When the d
resistors (see Figure 2), the total dynamic impedance
of the circuit is given by:
Zka Zka0
impedance when VKA = Vref is defined as :
VKA
∆
=
IK
∆
evice is operating with two external
V
∆
= = × +
I
∆
R
1
1
R
2
TOP VIEW
1
2
3
4
8
RefCathode
7
NCNC
6
AnodeAnode
5
NCNC
2-2
Rev. 1.2
5/11/98
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