LTC1559-3.3/LTC1559-5
U
TYPICAL APPLICATION
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)
†
L11
22µH
1
SW
8
BACKUP
BATTERY
1.2V
+
C11
1µF
6.3V
R14
14k
V
BAK
7
V
CC
+
NiCd
3
C12
1µF
R15
100k
CTL
LTC1559-3.3
RESET
2
4
5
6
GND
RESET
RESET
PUSH-BUTTON
PS
BACKUP
BACKUP
C
IN
Q1
MAIN
BATTERY
4.5 TO 28V
+
C2
22µF
35V
× 2
N-CHANNEL
Si4412DY
0.1µF
13 16
TG
SW
V
EXTV
IN
14
15
9
4
CC
SFB
BOOST
LTC1435
INTV
C4
0.1
Q11
P-CHANNEL
Si9424DY
D1
CMDSH-3
L1*
R
SENSE**
0.033Ω
µF
10
µH
6
3
12
8
V
OUT
3.3V
V
OSENSE
CC
+
C
OUT
+
100µF
10V
I
SENSE
TH
C5
1000pF
C
C
2
1
7
×2
–
RUN/SS SENSE
330pF
D2
Q2
N-CH
Si4412DY
11
R1
35.7k
1%
MBRS140T3
C
BG
SGND PGND
OSC
C6
100pF
C3
+
4.7
µF
C
C
0.1
C2
SS
µ
5
10
16V
51pF
F
R5
C
R
OSC
C
20k
1%
68pF
10k
*SUMIDA CDRH125-10
**IRC LR2010-01-R033-F
†
SUMIDA CD54-220
1559 TA04
C1
100pF
Description
batteryisrestored.Thus,theLTC1559doesnotusethePS
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.
With its SENSE pin at the source of Q11, the LTC1435 can
raise VOUT above VCC(rated voltage) – 5.5% once the main
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC690/LTC691 Microprocessor Supervisory Circuits
LTC694/LTC695
Microprocessor Power Supply Monitor and Backup with Power Fail
Comparator
LTC699
Microprocessor Supervisory Circuits
Microprocessor Supervisory Circuits
Microprocessor Supervisory Circuits
Microprocessor Power Supply Monitor and Backup
Include Push-Button Reset
LTC1232
LTC1235
LTC1149
Include Push-Button Reset and Power Fail Comparator
High Efficiency Synchronous Step-Down
Switching Regulator
V
IN
up to 48V, Burst ModeTM Operation
LTC1435
LTC1479
LTC1558
High Efficiency, Low Noise Synchronous
Step-Down Switching Regulator
Ultrahigh Efficiency, Burst Mode Operation
PowerPathTM Controller for Dual
Battery Systems
Complete Power Management Controller for Battery
Notebook Computers and Other Portable Equipment
Battery Backup Controller with
Programmable Output
Similar to LTC1559 Except That It Backs up the Main System Regulator’s
Input, Allowing Backup of Multiple Output Voltages
PowerPath and Burst Mode are trademarks of Linear Technology Corporation.
1559f LT/TP 1098 4K • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1998
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
20
●
●
(408)432-1900 FAX:(408)434-0507 www.linear-tech.com
Linear [ Linear ]
