20
LTC1559-3.3/LTC1559-5
LINEAR TECHNOLOGY CORPORATION 1998
LTC1559-3.3 Backup System with an LTC1435 Main System Regulator
(LTC1435 Output Sense at the Source of Q11, LTC1559’s PS Pin Is Grounded)
1559f LT/TP 1098 4K • PRINTED IN USA
PART NUMBER DESCRIPTION COMMENTS
LTC690/LTC691 Microprocessor Supervisory Circuits Microprocessor Power Supply Monitor and Backup with Power Fail
LTC694/LTC695 Comparator
LTC699 Microprocessor Supervisory Circuits Microprocessor Power Supply Monitor and Backup
LTC1232 Microprocessor Supervisory Circuits Include Push-Button Reset
LTC1235 Microprocessor Supervisory Circuits Include Push-Button Reset and Power Fail Comparator
LTC1149 High Efficiency Synchronous Step-Down V
IN
up to 48V, Burst Mode
TM
Operation
Switching Regulator
LTC1435 High Efficiency, Low Noise Synchronous Ultrahigh Efficiency, Burst Mode Operation
Step-Down Switching Regulator
LTC1479 PowerPath
TM
Controller for Dual Complete Power Management Controller for Battery
Battery Systems Notebook Computers and Other Portable Equipment
LTC1558 Battery Backup Controller with Similar to LTC1559 Except That It Backs up the Main System Regulator’s
Programmable Output Input, Allowing Backup of Multiple Output Voltages
PowerPath and Burst Mode are trademarks of Linear Technology Corporation.
RELATED PARTS
Description
With its SENSE pin at the source of Q11, the LTC1435 can
raise V
OUT
above V
CC
(rated voltage) – 5.5% once the main
TYPICAL APPLICATION
U
+
BG
SENSE
–
SENSE
+
INTV
CC
BOOST
SW
C
OSC
SGND PGND
RUN/SS
I
TH
V
OSENSE
V
IN
LTC1435
TG
C4
0.1
µF
R
SENSE**
0.033Ω
L1*
10
µH
*SUMIDA CDRH125-10
**IRC LR2010-01-R033-F
†
SUMIDA CD54-220
C3
4.7
µF
16V
D1
CMDSH-3
1559 TA04
D2
MBRS140T3
R5
20k
1%
R1
35.7k
1%
C5
1000pF
C6
100pF
Q2
N-CH
Si4412DY
Q1
N-CHANNEL
Si4412DY
SFB
EXTV
CC
11
7
8
12
15
14
13
C
IN
22µF
35V
× 2
16
5
10
1
2
3
6
4
9
C
OSC
68pF
R
C
10k
C
SS
0.1µF
C
C
330pF
C1
100pF
C
C2
51pF
+
C2
0.1µF
V
OUT
3.3V
CTL
C11
1µF
6.3V
BACKUP
BATTERY
1.2V
NiCd
MAIN
BATTERY
4.5 TO 28V
Q11
P-CHANNEL
Si9424DY
R14
14k
SW
LTC1559-3.3
L11
†
22µH
GND
PS
7
1
8
5
6
3
RESET
PUSH-BUTTON
2
4
V
BAK
V
CC
RESET
BACKUP
+
R15
100k
C12
1µF
RESET
BACKUP
+
C
OUT
100µF
10V
×2
+
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear-tech.com
battery is restored. Thus, the LTC1559 does not use the PS
pin to sense the LTC1435’s output during backup mode.
The PS pin is grounded in this case. Please refer to the
Applications Information section for more details.
