Datasheet

(Typical Application Circuit, V
S
= +14V, C
IN
= 10μF, C
OUT
= 10μF, V
SI
= 0V, V
EN
= +2.4V, V
OUT
= +5V, T
A
= +25°C, unless
otherwise noted.)
PIN NAME FUNCTION
1 V
S
Regulator Input. Operating supply range is from +5V to +28V and withstands 40V transients. Bypass
V
S
to GND with a 10µF capacitor.
2 SI
Voltage Sense/Power-Fail Comparator Input. SI is the noninverting input of an uncommitted comparator. SO
asserts low if V
SI
drops below the reference level, V
ST
.
3 EN
Enable Input. Leave unconnected (or pull EN high) to turn on the regulator. Pull EN low to place the device in
shutdown mode. EN is internally pulled up to 3.6V.
4 CT
Reset Timeout Delay Capacitor Connection. Connect a capacitor from CT to GND to program the reset timeout
period/reset pulse delay. During regulation, CT is pulled up to V
OUT
. CT is pulled low during reset, when EN is
low, or when in thermal shutdown.
5 GND
Ground. Bypass the input and output capacitors to the GND plane. Solder to large pads or the circuit-board
ground plane to maximize thermal dissipation.
6
RES
Active-Low Reset Output. Pull up externally to V
OUT
. Open-drain RES goes low when V
OUT
is below the reset
threshold. Once output voltage is in regulation, RES goes high after the programmed reset timeout period is
over. RES is low when EN is low or in thermal shutdown.
7 SO
Voltage Sense/Power-Fail Comparator Output. Pull up externally to V
OUT
. Open-drain SO asserts
low when V
SI
drops below the reference level, V
ST
. SO also asserts low when EN is low or in thermal
shutdown.
8 V
OUT
Regulator Output. Fixed at +5V (MAX5091A) or +3.3V (MAX5091B). Bypass with a 10µF ceramic capacitor to
GND.
EP EP
Exposed Paddle. EP is internally connected to GND. Connect EP to GND to provide a low thermal-resistance
path from the IC junction to the PC board. Do not use as the only electrical connection to GND.
V
OUT
STARTUP RESPONSE
MAX5091 toc21
10ms/div
V
OUT
2V/div
V
S
5V/div
0V
0V
I
OUT
= 10mA
ENABLE RESPONSE
MAX5091 toc22
200µs/div
V
OUT
5V/div
EN
5V/div
0V
0V
I
OUT
= 100mA
SHUTDOWN RESPONSE
MAX5091 toc23
200µs/div
V
OUT
2V/div
EN
2V/div
0V
0V
I
OUT
= 100mA
MAX5091 28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
www.maximintegrated.com
Maxim Integrated │ 8
Pin Description
Typical Operating Characteristics (continued)