LTC1471_15 Datasheet, PDF (8/12 Pages) Linear Technology – Single and Dual PCMCIA Protected 3.3V/5V VCC Switches

LTC1470/LTC1471
APPLICATIONS INFORMATION
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_CC
switching. This increases system configuration flexibility
and reduces total system cost by eliminating the need for a
third regulator for 12V power.
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
10
V_IN
V_IN
6.5V TO 18V
+
PDRIVE ⁹
Q1
C1
68µF
D1
MBRS140
R4
22Ω
C4
1000pF
(15V)
V_S V_S
AVPPEN0 AEN0 AVPP_OUT
+
AVPPEN1 AEN1
1/2 LTC1142HV
(5V REG)
NDRIVE ²⁰
SENSE^{+ 15}
D3
Q2
MBRS130T3
D2
MBRS140
AVALID AVALID
T1*
R1 _30µH
1.8:1
+
C5
LT1313
100Ω
22µF
BVPPEN0 BEN0
ASENSE
SENSE^{– 14}
C2
1000pF ^R2
100Ω
R3
18k
R5
0.033Ω
+ _C3
220µF
BVPPEN1 BEN1 BVPP_OUT
+
5V
BVALID BVALID
OUTPUT
BSENSE
GND GND
Q3
2N7002
Q4
2N7002
AVPPEN0
BVPPEN0
3.3V
0.1µF
* LPE-6562-A026 DALE [phone]
A3V_IN A3V_IN B3V_IN B3V_IN
5V
A5V_IN
BOUT
0.1µF
AV_CCEN0
B5V_IN
BOUT ₊
1µF
LTC1471
TANT
AEN0
AV_CCEN1
AEN1
BV_CCEN0
BEN0
AOUT
BV_CCEN1
BEN1
GND
AOUT
GND
+ _1µF
TANT
TO “A” SLOT
VPP PINS
1µF
FROM “A” V_CC PINS
TO “B” SLOT
VPP PINS
1µF
FROM “B” V_CC PINS
TO “A” SLOT
V_CC PINS
10k
TO “B” SLOT
V_CC PINS
10k
1470/71 F03
Figure 3. Cost Effective Complete SafeSlot Dual PCMCIA Power Management System
(with 15V Auxiliary Supply from LTC1142HV 5V Regulator Inductor)
14701fa
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