Datasheet

LT1110
5
W
IDAGRA
B
L
O
C
K
LT
1110
CCHARA TERIST
ICS
UW
AT
Y
P
I
CA
LPER
F
O
R
C
E
Set Pin Bias Current FB Pin Bias Current Reference Voltage
I
LIM
(Pin 1): Connect this pin to V
IN
for normal use. Where
lower current limit is desired, connect a resistor between
I
LIM
and V
IN
. A 220Ω resistor will limit the switch current
to approximately 400mA.
V
IN
(Pin 2): Input supply voltage.
SW1 (Pin 3): Collector of power transistor. For step-up
mode connect to inductor/diode. For step-down mode
connect to V
IN
.
SW2 (Pin 4): Emitter of power transistor. For step-up
mode connect to ground. For step-down mode connect to
inductor/diode. This pin must never be allowed to go more
than a Schottky diode drop below ground.
GND (Pin 5): Ground.
AO (Pin 6): Auxiliary Gain Block (GB) output. Open collector,
can sink 300µA.
SET (Pin 7): GB input. GB is an op amp with positive input
connected to SET pin and negative input connected to
220mV reference.
FB/SENSE (Pin 8): On the LT1110 (adjustable) this pin
goes to the comparator input. On the LT1110-5 and
LT1110-12, this pin goes to the internal application resistor
that sets output voltage.
PI
U
FU
U
C
U
S
O
TI
TEMPERATURE (°C)
BIAS CURRENT (nA)
–50
LT1110 • TPC13
160
140
120
100
60
–25
20
0
40
80
0 25 50 75 100
TEMPERATURE (°C)
V
REF
(mV)
–50 –25 0 25
LT1110 • TPC15
50 75 100
226
224
222
220
218
216
214
212
TEMPERATURE (°C)
BIAS CURRENT (nA)
–50
120
100
90
70
40
–25
10
0
30
60
0 25 50 75 100
20
50
80
110
LT1110 • TPC14
LT1110 • BD01
IN
V
GND
SET
AO
GAIN BLOCK/ERROR AMP
220mV
REFERENCE
A1
A2
DRIVER
+
–
FB
SW1
SW2
LIM
I
OSCILLATOR
COMPARATOR
Q1