LTC1471 LINER [Linear Technology], LTC1471 Datasheet - Page 8

• Manufacturer Part Number: LTC1471
• Description: Single and Dual PCMCIA Protected 3.3V/5V VCC Switches
• Manufacturer: LINER [Linear Technology]

APPLICATIONS
TOTAL SYSTEM COST CONSIDERATIONS
The cost of an additional step-up switching regulator, induc-
tor, rectifier and capacitors to produce 12V for VPP can be
eliminated by using an auxiliary winding on either the 3.3V
or 5V output of the system switching regulator to produce an
auxiliary 15V supply for VPP power.
And, because the LTC1470/LTC1471 do not require 12V
power to operate (only 5V), the 12V VPP regulation and
switching may be operated separately from the 3.3V/5V V
switching. This increases system configuration flexibility
and reduces total system cost by eliminating the need for a
third regulator for 12V power.
LTC1470/LTC1471
8
1/2 LTC1142HV
* LPE-6562-A026 DALE [phone]
(5V REG)
AVPPEN0
SENSE
SENSE
PDRIVE
NDRIVE
Q3
2N7002
V
IN
+
–
BVPPEN0
U
10
9
20
15
14
6.5V TO 18V
Figure 3. Cost Effective Complete SafeSlot Dual PCMCIA Power Management System
(with 15V Auxiliary Supply from LTC1142HV 5V Regulator Inductor)
INFORMATION
U
V
IN
Q1
Q2
R3
18k
Q4
2N7002
C2
1000pF
+
D3
MBRS130T3
100
100
W
R2
R1
C1
68 F
30 H
T1*
+
R5
0.033
U
C3
220 F
1.8:1
22
R4
MBRS140
MBRS140
D1
CC
D2
3.3V
1000pF
5V
C4
+
LTC1142HV Auxiliary Winding Power Supply
Figure 3 is a schematic diagram which describes how a
loosely regulated 15V power supply is created by adding an
auxiliary winding to the 5V inductor in a split 3.3V/5V
LTC1142HV power supply system. An LT1313, dual VPP
regulator/driver with SafeSlot protection, produces “clean”
3.3V, 5V and 12V power from this loosely regulated 15V
output for the PC card slot VPP pins. (See LT1312 and
LT1313 data sheets for further detail.)
A turns ratio of 1:1.8 is used for transformer T1 to ensure that
the input voltage to the LT1313 falls between 13V and 20V
under all load conditions. The 9V output from this additional
AV
AV
BV
BV
0.1 F
0.1 F
C5
22 F
CC
CC
CC
CC
5V
OUTPUT
EN0
EN1
EN0
EN1
AVPPEN0
AVPPEN1
BVPPEN0
BVPPEN1
(15V)
A3V
A5V
B5V
AEN0
AEN1
BEN0
BEN1
AVALID
BVALID
IN
IN
IN
GND
A3V
LTC1471
IN
B3V
AEN0
AEN1
AVALID
BEN0
BEN1
BVALID
GND
IN
GND
V
S
BOUT
BOUT
LT1313
B3V
AOUT
AOUT
IN
AVPP
BVPP
GND
ASENSE
BSENSE
V
S
OUT
OUT
+
+
1 F
TANT
1 F
TANT
+
+
1 F
1 F
10k
10k
FROM “A” V
FROM “B” V
TO “A” SLOT
V
TO “B” SLOT
V
TO “A” SLOT
VPP PINS
TO “B” SLOT
VPP PINS
CC
CC
PINS
PINS
CC
CC
1470/71 F03
PINS
PINS