LT1618 LINER [Linear Technology], LT1618 Datasheet - Page 4

• Manufacturer Part Number: LT1618
• Description: Constant-Current/ Constant-Voltage 1.4MHz Step-Up DC/DC Converter
• Manufacturer: LINER [Linear Technology]

LT1618
PIN
FB (Pin 1): Feedback Pin. Set the output voltage by
selecting values for R1 and R2 (see Figure 1):
ISN (Pin 2): Current Sense (–) Pin. The inverting input to
the current sense amplifier.
ISP (Pin 3): Current Sense (+) Pin. The noninverting input
to the current sense amplifier.
I
applied to this pin will reduce the current sense voltage. If
this adjustment is not needed, tie this pin to ground.
TYPICAL PERFOR A CE CHARACTERISTICS
4
ADJ
R
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
U
1
– 50
(Pin 4): Current Sense Adjust Pin. A DC voltage
Switching Frequency
FUNCTIONS
R
– 25
2
U
1 263
V
.
OUT
0
TEMPERATURE ( C)
V
IN
V
25
= 18V
–
U
1
50
V
IN
75
= 1.6V
W
100
1618 G07
U
125
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
Frequency Foldback
T
J
= 25 C
0.2
FEEDBACK PIN VOLTAGE (V)
0.4
0.6
GND (Pin 5): Ground Pin. Tie this pin directly to local
ground plane.
SW (Pin 7 ): Switch Pin. This is the collector of the internal
NPN power switch. Minimize the metal trace area con-
nected to this pin to minimize EMI.
V
capacitor to ground as close to the device as possible.
SHDN (Pin 9): Shutdown Pin. Tie this pin higher than 1V
to turn on the LT1618; tie below 0.3V to turn it off.
V
nect a series RC from this pin to ground. Typical values are
2k and 10nF.
IN
C
(Pin 10): Compensation Pin for Error Amplifier. Con-
(Pin 8): Input Supply Pin. Bypass this pin with a
0.8
1.0
1618 G08
1.2
50
45
40
35
30
25
20
15
10
5
0
SHDN Pin Current
0
SHUTDOWN PIN VOLTAGE (V)
5
T
J
= – 50 C
10
T
J
= 25 C
T
J
= 125 C
15
1618 G09
20