LT1614 Linear Technology, LT1614 Datasheet - Page 4

• Manufacturer Part Number: LT1614
• Description: Inverting 600kHz Switching Regulator
• Manufacturer: Linear Technology

PIN
BLOCK
LT1614
NFB (Pin 1): Negative Feedback Pin. Reference voltage is
– 1.24V. Connect resistive divider tap here. The sug-
gested value for R2 is 24.9k. Set R1 and R2 according to:
V
nect a series RC from this pin to ground. Typical values
are 100k and 1nF. Minimize trace area at V
SHDN (Pin 3): Shutdown. Ground this pin to turn off
switcher. Must be tied to V
switcher. Do not float the SHDN pin.
4
C
R
U
(Pin 2): Compensation Pin for Error Amplifier. Con-
1
FUNCTIONS
1 24
R
.
U
2
|
DIAGRAM
V
V
OUT
V
OUT
6
IN
R1
(EXTERNAL)
R2
(EXTERNAL)
4 5 10
| – .
. •
NFB
1 24
Q1
U
R5
40k
–
W
6
IN
NFB
1
(or higher voltage) to enable
Q2
R6
40k
R3
30k
R4
140k
10
V
IN
+
–
OSCILLATOR
GENERATOR
600kHz
RAMP
g
AMPLIFIER
m
ERROR
C
.
+
+
BIAS
V
–
–
+
+
2
C
COMPARATOR
GND (Pin 4): Ground. Connect directly to local ground
plane.
SW (Pin 5): Switch Pin. Minimize trace area at this pin to
keep EMI down.
V
capacitor right at the pin, connected directly to ground.
LBI (Pin 7): Low-Battery Detector Input. 200mV refer-
ence. Voltage on LBI must stay between ground and
700mV. Float this pin if not used.
LBO (Pin 8): Low-Battery Detector Output. Open collec-
tor, can sink 10 A. A 1M pull-up is recommended. Float
this pin if not used.
IN
A1
A2
(Pin 6): Supply Pin. Must have 1 F ceramic bypass
ENABLE
R
200mV
FF
S
LBI
7
Q
+
–
SHUTDOWN
DRIVER
A = 3
A4
+
–
SHDN
LBO
GND
SW
3
8
5
4
Q3
0.15
1614 BD