AMS431L
TEST CIRCUITS
VZ = VREF
VZ
VZ
VIN
VIN
VIN
IREF
IZ OFF
R1
R2
IREF
IZ
IZ
VREF
VREF
Figure 1. Test Circuit for VZ=VREF
Figure 2. Test Circuit for VREF vs IZ.
Test circuit for IREF
Figure 3. Test Circuit for Off-State Current
.
TYPICAL APPLICATIONS
VIN
VOUT
R1
VREF
R2
GND
1) Set the VOUT according to the following equation:
R1
VOUT = VREFæ1+
ö
÷
ø
+ IREFR1
ç
è
R2
2) Choose the value of R as follows:
·
·
The maximum limit for R should be such that the cathode current, IZ is greater than the minimum operating current (80mA) at VIN(min).
The minimum limit for R should b such that IZ does not exceed 100mA under all load conditions, and the instantaneous turn-on value for IZ does not exceed
150mA. Both of the following conditions must be met:
VIN(max)
Rmin ³
Rmin ³
(
to limit instantaneous turn - on IZ
)
150mA
VIN(max) - VOUT
(to limit IZ under normal operating conditions
)
IOUT(min) +100mA
3
Advanced Monolithic Systems http://www.ams-semitech.com
AMS [ Advanced Monolithic Systems Ltd ]
