APPLICATION HINTS (Continued)
+VIN
4.75V
OUTPUT
VOLTAGE
8
+VIN
ERROR*
100k
VOUT
1.2 30V
5
3
1
ERROR
OUPUT
ERROR*
VOUT
AMS2951
*
+
**SHUTDOWN
INPUT
3.3µF
SD
R1
.01
5V
INPUT
VOLTAGE
µF
GND
FB
4
7
1.23V
VREF
1.3V
R2
FIGURE 1. ERROR Output Timing
FIGURE 2. Adjustable Regulator
*See Application Hints.
*When VIN ≤1.3V the error flag pin becomes a high impedance,
and the error flag voltage rises to its pull-up voltage. Using Vout
as the pull-up voltage (see Figure 2), rather than an external 5V
source, will keep the error flag voltage under 1.2V (typ.) in this
condition. The user may wish to drive down the error flag voltage
using equal value resistors (10 kΩ suggested), to ensure a low-
level logic signal during any fault condition, while still allowing
a valid high logic level during normal operation.
Vout = VREF × (1 + R1/ R2)
**Drive with TTL- high to shut down. Ground or leave if shutdown
feature is not used.
Note: Pins 2 and 6 are left open.
TYPICAL APPLICATIONS
300 mA Regulator with 0.75 Dropout
Wide Input Voltage Range Current Limiter
UNREGULATED
INPUT
+VIN
330Ω
8
6
1
2
IN
OUT
2N5432 (2)
8
+VIN
27kΩ
AMS2951
*VOUT≈ VΙΝ
5
3
1
ERROR
OUPUT
VOUT
ERROR
5V OUTPUT
VTAP
SENSE
GND
AMS2951
LOAD
50mA TO
300mA
FB
SHUTDOWN
INPUT
SD
GND
4.7µ
F
7
4
FB
4
7
*Minimum Input-Output voltage ranges from 40mV to 400mV, depending on
load current. Current limit is typically 160 mA
Advanced Monolithic Systems http://www.ams-semitech.com
AMS [ Advanced Monolithic Systems Ltd ]
