LT3020/LT3020-1.2/
LT3020-1.5/LT3020-1.8
PI FU CTIO S
OUT (Pins 1, 2):
These pins supply power to the load. Use
a minimum output capacitor of 2.2µF to prevent oscillations.
Applications with large load transients require larger out-
put capacitors to limit peak voltage transients. See the
Applications Information section for more information on
output capacitance and reverse output characteristics.
OUT (Pin 3, Fixed Voltage Device Only):
This pin is the
sense point for the internal resistor divider. It should be
tied directly to the other OUT pins (1, 2) for best results.
ADJ (Pin 3, Adjustable Device Only):
This pin is the
inverting terminal to the error amplifier. Its typical input
bias current of 20nA flows out of the pin (see curve of ADJ
Pin Bias Current vs Temperature in the Typical Perfor-
mance Characteristics). The ADJ pin reference voltage is
200mV (referred to GND).
GND (Pin 4):
Ground.
SHDN (Pin 5):
The SHDN pin puts the LT3020 into a low
power state. Pulling the SHDN pin low turns the output off.
Drive the SHDN pin with either logic or an open collector/
drain device with a pull-up resistor. The pull-up resistor
supplies the pull-up current to the open collector/drain
logic, normally several microamperes, and the SHDN pin
current, typically 2.3µA. If unused, connect the SHDN pin
to V
IN
. The LT3020 does not function if the SHDN pin is not
connected.
IN (Pins 7, 8):
These pins supply power to the device. The
LT3020 requires a bypass capacitor at IN if it is more than
six inches away from the main input filter capacitor. The
output impedance of a battery rises with frequency, so
include a bypass capacitor in battery-powered circuits. A
bypass capacitor in the range of 2.2µF to 10µF suffices. The
LT3020 withstands reverse voltages on the IN pin with
respect to ground and the OUT pin. In the case of a reversed
input, which occurs if a battery is plugged in backwards,
the LT3020 acts as if a diode is in series with its input. No
reverse current flows into the LT3020 and no reverse volt-
age appears at the load. The device protects itself and the
load.
GND (Pin 9, DD8 Package Only):
Ground. Solder Pin 9
(the exposed pad) to the PCB. Connect directly to Pin 4 for
best performance.
BLOCK DIAGRA
SHDN
(5)
SHUTDOWN
200mV
BIAS CURRENT
AND
REFERENCE
GENERATOR
212mV
–
NO-LOAD
RECOVERY
Q2
R2
25k
NOTE:
FOR LT3020 ADJUST PIN 3 IS CONNECTED TO
THE ADJUST PIN, R1 AND R2 ARE EXTERNAL.
FOR LT3020-1.X PIN 3 IS CONNECTED TO THE
OUTPUT SENSE PIN, R1 AND R2 ARE INTERNAL.
8
+
–
W
U
U
U
IN
(7, 8)
THERMAL
SHUTDOWN
R3
D1
Q3
CURRENT
GAIN
Q1
ERROR AMP
D2
OUT
(1, 2)
OUT SENSE
(3)
+
ADJ
(3)
FIXED
V
OUT
1.2V
1.5V
1.8V
R1
R1
R2
GND
(4,9)
3020 BD
20k 100k
20k 130k
20k 160k
sn3020 3020fas
LINER [ LINEAR TECHNOLOGY ]
