5V/3.3V or Adjustable, Low-Dropout,
Low I
Q
, 200mA Linear Regulators
MAX882/MAX883/MAX884
INPUT
VOLTAGE
IN
LBI
R1
OUT
OUTPUT
VOLTAGE
INPUT
VOLTAGE
R1
LOAD
R2
C
OUT
2.2µF
C
IN
O.1µF
STBY
C
OUT
2.2µF
IN
LBI
OUT
OUTPUT
VOLTAGE
MAX882
OFF
MAX883
(STBY)
MAX884
C
IN
O.1µF
GND
MAX882
SET
R2
GND
SET
( ) ARE FOR MAX882
V
STBY TRIP
= V
STBY
R1 + R2
V
OUT
= V
SET
, V
SET
= 1.20V
R2
R1+ R2
, V
STBY
= 1.20V
R2
Figure 2. Adjustable Output Using External Feedback
Resistors
Figure 3. Setting an Undervoltage Lockout Threshold Using
STBY
Foldback Current Limiting
The MAX882/MAX883/MAX884 also include a foldback
current limiter. It monitors and controls the pass transis-
tor’s gate voltage, estimating the output current and
limiting it to 430mA for output voltages above 0.8V and
(V
IN
- V
OUT
) > 0.7V. If the output voltage drops below
0.8V, implying a short-circuit condition, the output cur-
rent is limited to 170mA. The output can be shorted to
ground for 1 minute without damaging the device if the
package can dissipate (V
IN
x 170mA) without exceed-
ing T
J
= +150°C. When the output is greater than 0.8V
and (V
IN
- V
OUT
) < 0.7V (dropout operation), no current
limiting is allowed, to provide maximum load drive.
Power Dissipation and Operating Region
Maximum power dissipation of the MAX882/MAX883/
MAX884 depends on the thermal resistance of the case
and circuit board, the temperature difference between
the die junction and ambient air, and the rate of
air flow. The power dissipation across the device is
P = I
OUT
(V
IN
- V
OUT
). The resulting power dissipation
is as follows:
(T
J
−
T
A
)
P
=
(
θ
JB
+ θ
BA
)
where (T
J
- T
A
) is the temperature difference between
the MAX882/MAX883/MAX884 die junction and the sur-
rounding air,
θ
JB
(or
θ
JC
) is the thermal resistance of
the package chosen, and
θ
BA
is the thermal resistance
through the printed circuit board, copper traces, and
other materials to the surrounding air.
The 8-pin small-outline package for the MAX882/
MAX883/MAX884 features a special lead frame with a
lower thermal resistance and higher allowable power
dissipation. This package’s thermal resistance package
is
θ
JB
= 53°C/W, compared with
θ
JB
= 110°C/W for an
8-pin plastic DIP package and
θ
JB
= 125°C/W for an 8-
pin ceramic DIP package.
Thermal Overload Protection
Thermal overload protection limits total power dissipa-
tion in the MAX882/MAX883/MAX884. When the junc-
tion temperature exceeds T
J
=+160°C, the thermal
sensor sends a signal to the shutdown logic, turning off
the pass transistor and allowing the IC to cool. The
thermal sensor turns the pass transistor on again after
the IC’s junction temperature cools by 10°C, resulting in
a pulsed output during thermal overload conditions.
Thermal overload protection is designed to protect the
MAX882/MAX883/MAX884 if fault conditions occur. It is
not intended to be used as an operating mode.
Prolonged operation in thermal shutdown mode may
reduce the IC’s reliability. For continual operation, do
not exceed the absolute maximum junction temperature
rating of T
J
= +150°C.
_______________________________________________________________________________________
9
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
