5V/3.3V or Adjustable, Low-Dropout,
Low I
Q
, 200mA Linear Regulators
MAX882/MAX883/MAX884
IN
LBI
LBO
N
ERROR AMP
LOW-BATTERY
COMPARATOR
MOSFET DRIVER
WITH FOLDBACK
CURRENT LIMIT
P
REVERSE-
CURRENT
PROTECTION
OFF
(STBY)
SHUT-
DOWN
LOGIC
1.20V
REFERENCE
DUAL-MODE
COMPARATOR
R1
OUT
SET
THERMAL
SENSOR
GND
R2
65mV
( ) ARE FOR MAX882
Figure 1. MAX882/MAX883/MAX884 Functional Diagram
In adjustable mode, the user selects an output voltage
in the 1.25V to 11V range by connecting two external
resistors, used as a voltage divider, to the SET pin
(Figure 2).
The output voltage is set by the following equation:
R1
V
OUT
=
V
SET
1
+
R2
where V
SET
= 1.20V.
To simplify resistor selection:
V
R1
=
R2
OUT
−
1
V
SET
Since the input bias current at SET is nominally zero,
large resistance values can be used for R1 and R2 to
minimize power consumption without losing accuracy.
Up to 1.5MΩ is acceptable for R2. Since the V
SET
toler-
ance is less than ±40mV, the output can be set using
fixed resistors instead of trim pots.
Standby Mode (MAX882)
The MAX882 has a standby feature that disconnects
the input from the output when STBY is brought low, but
keeps all other circuitry awake. In this mode, V
OUT
drops to 0V, and the internal biasing circuitry (including
the low-battery comparator) remains on. The maximum
quiescent current during standby is 15µA. STBY is a
comparator input with the other input internally tied to
the reference voltage. Use a resistor network as shown
in Figure 3 to set a standby-mode threshold voltage for
undervoltage lockout. Connect STBY to IN for normal
operation.
OFF Mode (MAX883/MAX884)
A low-logic input on the OFF pin shuts down the
MAX883/MAX884. In this mode, the pass transistor,
control circuit, reference, and all biases are turned off,
and the supply current is reduced to less than 1µA.
LBO is undefined in OFF mode. Connect OFF to IN for
normal operation.
8
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