LTC1539 LINER [Linear Technology], LTC1539 Datasheet - Page 9

• Manufacturer Part Number: LTC1539
• Description: Dual High Efficiency, Low Noise, Synchronous Step-Down Switching Regulators
• Manufacturer: LINER [Linear Technology]

PIN
noninverting input of a comparator whose inverting input
is tied to the internal 1.19V reference. See Auxiliary Regu-
lator Application section.
AUXON: Pulling this pin high turns on the auxiliary regu-
lator/comparator. The threshold is 1.19V. This is a conve-
nient linear power supply logic-controlled on/off input.
FUNCTIONAL DIAGRA
C
BATTERY
LP
V
V
SENSE
LDO
SEC
U
U
+
C
OSC
+
FUNCTIONS
V
IN
f
R
IN
LP
U
PLL LPF**
AUXON
AUXDR
EXTV
INTV
AUXFB
PLLIN**
SGND
POR1**
C
SFB1*
LBO**
LBI**
V
*NOT AVAILABLE ON BOTH CHANNELS
OSC
IN
CC
CC
U
1 A
50k
4.8V
U
–
+
OSCILLATOR
POWER-ON
DETECTOR
PHASE
90.8k
RESET
+
–
9V
–
+
–
+
2.4V
SFB
+
–
V
1.11V
FB1
10k
**NOT AVAILABLE ON LTC1538-AUX
REGULATOR
INTERNAL
SUPPLY
5V LDO
W
1.19V
REF
LTC1539 shown, see specific package pinout for availability of specific functions.
V
REF
DUPLICATE FOR SECOND CONTROLLER CHANNEL
6V
3 A
S
R
0.6V
Q
Q
†
FOLDBACK CURRENT LIMITING OPTION
180k
DETECTOR
DROPOUT
g
SHUTDOWN
m
+
–
+
–
= 1m
OV
1.28V
1.19V
30k
AUXDR: Open Drain Output of the Auxiliary Regulator/
Comparator. The base of an external PNP device is con-
nected to this pin when used as a linear regulator. An
external pull-up resistor is required for use as a compara-
tor. A voltage > 9.5V on AUXDR causes the internal 12V
resistive divider to be connected in series with the AUXFB pin.
I1
SOFT START
+
–
EA
+
–
RUN
SHUTDOWN
+
–
8k
V
SFB
FB
LTC1538-AUX/LTC1539
SWITCH
LOGIC
BOLD LINES INDICATE HIGH CURRENT PATHS
61k
119k
320k
I2
4k
INTV
–
+
CC
INTV
CC
V
SENSE
SENSE
V
RUN/SS
BOOST
OSENSE
PGND
PROG
TGS**
TGL
SW
BG
I
TH
*
–
+
*
V
IN
C
C
D
C
OUT
FB
†
C
+
V
SS
R
+
OUT
C
R
INTV
SENSE
C
IN
•
CC
D
C
C
B
9
SEC
B
1438 FD
+
•