MAX1806
500mA, Low-Voltage Linear Regulator in µMAX
6 _______________________________________________________________________________________
Pin Description
PIN NAME FUNCTION
1, 2 IN
Regulator Input. Supply voltage can range from +2.25V to +5.5V. Bypass with a 1µF capacitor to GND (see
Capacitor Selection and Regulation Stability). Connect both input pins together externally.
3 POK
Open-Drain, Active-Low Power-OK Output. POK remains low while the output voltage (V
OUT
) is below the
POK threshold. Connect a 100kΩ pullup resistor from POK to OUT.
4 SHDN
Active-Low Shutdown Input. A logic low at SHDN reduces supply current to 0.02µA. In shutdown, the POK
output is low. Connect SHDN to IN for normal operation.
5 GND
Ground. This pin and the exposed pad also function as a heatsink. Solder both to a large pad or to the
circuit-board ground plane to maximize power dissipation.
6 SET
Voltage-Setting Input. Connect SET to GND for preset output. Connect an external resistive voltage-divider
from OUT to SET to set the output voltage between 0.8V and 4.5V. The SET regulation voltage is 800mV.
7, 8 OUT
Regulator Output. OUT sources up to 500mA. Bypass OUT with a 10µF low-ESR capacitor to GND.
Connect both OUT pins together externally.
LINE-TRANSIENT RESPONSE
MAX1806 toc15
200µs/div
V
IN
1V/div
6V
3V
V
OUT
10mV/div
SHUTDOWN WAVEFORM
MAX1806 toc16
20µs/div
2V
3V
0
0
V
OUT
1V/div
R
OUT
= 6.6Ω (500mA)
V
SHDN
1V/div
Typical Operating Characteristics (continued)
(MAX1806EUA33, V
IN
= V
OUT
+ 500mV, SHDN = IN, C
IN
= 1µF, C
OUT
= 10µF, T
A
= +25°C, unless otherwise noted.)
LOAD-TRANSIENT RESPONSE
NEAR DROPOUT
MAX1806 toc14
10µs/div
I
OUT
200mA/div
V
OUT
50mV/div
V
IN
= V
OUT
+ 100mV
C
IN
= 10µF
R
OUT
= 660Ω TO
6.6Ω (5mA TO 500mA)
POK WAVEFORM
MAX1806 toc17
200µs/div
V
IN
2V/div
V
OUT
2V/div
5V
0
0
0
V
POK
2V/div
R
OUT
= 66Ω (50mA)