lt3022emse Linear Technology Corporation, lt3022emse Datasheet - Page 9

• Manufacturer Part Number: lt3022emse
• Description: Lt3022 1a, 0.9v To 10v, Very Low Dropout Linear Regulator Features
• Manufacturer: Linear Technology Corporation

block DiagraM
applicaTions inForMaTion
The LT3022 very low dropout linear regulator is capable of
0.9V input supply operation. It supplies 1A output current
and dropout voltage is typically 145mV. Quiescent current
is typically 400µA and drops to 7.5µA in shutdown. The
LT3022 incorporates several protection features, making
it ideal for use in battery-powered systems. The device
protects itself against reverse-input and reverse-output
voltages. If the output is held up by a backup battery when
the input is pulled to ground in a battery backup application,
the LT3022 behaves as if a diode is in series with its output,
preventing reverse current flow. In dual supply applications
where the regulator load is returned to a negative supply,
pulling the output below ground by as much as 10V does
not affect start-up or normal operation.
Adjustable Operation
The LT3022’s output voltage range is 0.2V to 9.5V. Figure 1
shows that the external resistor ratio sets output voltage.
The device regulates the output to maintain ADJ at 200mV
referred to ground. R1’s current equals 200mV/R1. R2’s
current is R1’s current minus the ADJ pin bias current.
The 30nA ADJ pin bias current flows out of the pin. Use
Figure 1’s formula to calculate output voltage. Given the
LT3022’s 1mA minimum load current requirement, Linear
9
SHDN
BIAS CURRENT
GENERATOR
SHUTDOWN
REFERENCE
AND
200mV
213mV
DIODE
IDEAL
RECOVERY
–
+
–
+
NO-LOAD
SHUTDOWN
ERROR
THERMAL
AMP
NOTE:
R1 AND R2 ARE EXTERNAL
TIE PGND, AGND AND THE EXPOSED PAD TOGETHER
CURRENT
Technology recommends choosing resistor divider values
to satisfy this requirement. A 200Ω R1 value sets a 1mA
resistor divider current. In shutdown, the output is off and
the divider current is zero. Curves of ADJ Pin Voltage vs
Temperature and ADJ Pin Bias Current vs Temperature ap-
pear in the Typical Performance Characteristics section.
Specifications for output voltages greater than 200mV
are proportional to the ratio of desired output voltage to
200mV (V
an output current change of 1mA to 1A is typically 0.1mV
at V
GAIN
25k
200
ADJ
1 5
.
mV
= 200mV. At V
+
V
V
V
I
OUTPUT RANGE: 0.2V TO 9.5V
ADJ
OUT
ADJ
OUT
: 30nA AT 25°C
: 200mV
: 200mV • (1 + R2/R1) – (I
• .
V
IN
0 1
/200mV). For example, load regulation for
Q1
Q2
Figure 1. Adjustable Operation
R3
D1
mV
10, 11
PGND
IN
SHDN
D2
=
750
LT3022
OUT
GND
µV
OUT
ADJ
= 1.5V, load regulation is:
Q3
R2
R1
3022 BD
ADJ
• R2)
12, 13, 14
R2
R1
3022 F01
AGND
OUT
ADJ
3, 4
6, 7
IN
5
LT3022
V
OUT

3022f