1
LT1106
Micropower Step-Up
DC/DC Converter for
PCMCIA Card Flash Memory
S
FEATURE
D
U
ESCRIPTIO
The LT
1106 is the industry's first DC/DC converter
designed for use on Type I and Type II PCMCIA cards. The
device senses the VPP1 and VPP2 lines at the PCMCIA
socket and generates a regulated 12V, 60mA program-
ming supply if the socket does not provide it. Internal logic
simplifies the interface to PCMCIA card microcontrollers.
One input selects a 12V or 5V regulated output, while
another input controls micropower shutdown. Two logic
outputs indicate when the selected programming voltage
is valid and whether the input supply is 3.3V or 5V.
The regulator features Burst Mode
TM
operation with a 0.5A,
300mV switch for efficiency up to 85%. High frequency
500kHz switching permits the use of small value, flat
inductors that fit neatly on PCMCIA cards. The device
requires just 1
F of output capacitance.
Quiescent current is 750
A which drops to 350
A when
the card runs off the socket supply. The shutdown pin
reduces supply current to only 10
A. The device includes
a soft start feature which limits supply current transients
when the card is inserted into a hot socket.
U
S
A
O
PPLICATI
s
PCMCIA Card Flash Memory VPP Generator
s
Portable Computers
s
Portable Instruments
s
DC/DC Converter Module Replacements
s
60mA Output Current at 12V from 3V Supply
s
Shutdown to 10
A
s
Programmable 12V or 5V Output
s
Up to 85% Efficiency
s
Quiescent Current: 750
A
s
Low V
CESAT
Switch: 300mV at 0.5A Typical
s
Uses Low Value, Thin, Surface Mount Inductors
s
Ultra-Thin 20-Lead TSSOP Package
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
LOAD CURRENT (mA)
1
70
EFFICIENCY (%)
72
74
76
78
86
10
100
LT1106 TA02
80
82
84
V
IN
= 5V
V
IN
= 5V
V
IN
= 3.3V
V
IN
= 3.3V
D1 = MBR0530
D1 = 4 BAT54Cs
IN PARALLEL
12V Output Efficiency
12V, 60mA Flash Memory Programming Supply
U
A
O
PPLICATI
TYPICAL
V
CC
VPP1
G1
VPP2
G2
ON/OFF
GND
PGND
SW
D
S
BSS84
D
S
BSS84
POWER ON
DALE ILS-3825-01 OR
COILTRONICS CTX02-11238-3
MOTOROLA MBR0530
*
**
LT1106 TA01
12/5
SOFT START
AVPP
1M
0.1
F
3/5 DETECT
VPP VALID
1
F
D1**
L1*
10
H
0.1
F
4.7
F
TANT
ALUM
VPP1
VPP2
V
CC
3.3V/5V
LT1106
VPP VALID
3/5
12V/60mA
0.1
F
0.1
F
470pF
+
2
LT1106
A
U
G
W
A
W
U
W
A
R
BSOLUTE
XI
TI
S
V
CC
Voltage ............................................................... 7V
V
SW
Voltage ............................................................ 20V
AVPP Voltage ......................................................... 20V
VPP1, VPP2 Voltage ............................................... 20V
G1, G2 Voltage ....................................................... 20V
V
ON/OFF
Voltage......................................................... 7V
V
SEL
Voltage ............................................................. 7V
I
LIM
Voltage .............................................................. 7V
Maximum Power Dissipation ............................ 500mW
Operating Temperature Range ..................... 0
C to 70
C
Storage Temperature Range ................. 65
C to 150
C
Lead Temperature (Soldering, 10 sec).................. 300
C
LT1106CF
W
U
U
PACKAGE/ORDER I FOR ATIO
Consult factory for Industrial and Military grade parts
T
JMAX
= 100
C,
JA
= 90
C/W
ORDER PART
NUMBER
ELECTRICAL C
C
HARA TERISTICS
T
A
= 25
C, V
CC
= 5V, V
ON/OFF
= 3V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
Q
Quiescent Current
V
SEL
= 0.2V, AVPP = 12V
750
900
A
Quiescent Current, Shutdown
V
ON/OFF
= 0.2V
9
15
A
"Doze" Mode Current
V
SEL
= 0.2V, VPP1 or VPP2 = 12V
320
A
Input Voltage Range
2
6
V
Output Sense Voltage
V
SEL
= 3V, VPP1 and VPP2 Floating
q
4.75
5
5.25
V
V
SEL
= 0.2V, VPP1 and VPP2 Floating
q
11.50
12
12.60
V
Output Referred
V
SEL
= 3V
15
mV
Comparator Hysteresis
V
SEL
= 0.2V
35
mV
f
OSC
Oscillator Frequency
Current Limit Not Asserted
400
500
700
kHz
DC
Maximum Duty Cycle
q
80
85
92
%
t
ON
Switch On-Time
1.7
s
Reference Line Regulation
2V < V
IN
< 6V
0.06
0.15
%/V
V
CESAT
Switch Saturation Voltage
I
SW
= 0.5A
230
350
mV
Switch Leakage Current
V
SW
= 12V, Switch Off
0.1
10
A
Switch Current Limit
V
IN
= 5V, Soft Start Floating
450
600
900
mA
V
IN
= 3V, Soft Start Floating
500
650
950
mA
Soft Start Pin Current
Soft Start Grounded
80
120
A
Select Input Voltage Low
0.8
V
Select Input Voltage High
1.6
V
ON/OFF Input Voltage Low
0.8
V
ON/OFF Input Voltage High
1.6
V
ON/OFF Bias Current
V
ON/OFF
= 5V
16.0
24.0
A
V
ON/OFF
= 3V
8.0
14.0
A
V
ON/OFF
= 0V
0.1
1.1
A
1
2
3
4
5
6
7
8
9
10
TOP VIEW
F PACKAGE
20-LEAD PLASTIC TSSOP
20
19
18
17
16
15
14
13
12
11
SELECT 12/5
SOFT START
V
CC
V
CC
3/5
PGND
PGND
NC
V
SW
V
SW
ON/OFF
AVPP
VPP1
VPP2
G1
G2
VPP VALID
GND
NC
V
SW
3
LT1106
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Select Pin Bias Current
0V < V
SEL
< 5V
0.1
1
A
VPP1/VPP2 Input Sense Threshold
11.0
11.5
11.9
V
AVPP Pin Input Current
50
90
A
V
ON/OFF
= 0.2V
0.1
1
A
VPP1/VPP2 Pin Input Current
50
90
A
V
ON/OFF
= 0.2V
0.1
1
A
VPP VALID Threshold
AVPP Rising (High to Low Transition)
q
11.4
12
V
VPP VALID Output Voltage Low
I
SINK
= 100
A
0.13
0.3
V
VPP VALID Output Voltage High
I
SOURCE
= 2.5
A
4
4.5
V
3/5 Comparator Threshold
q
3.6
3.75
4.2
V
3/5 Comparator Output High
I
LOAD
= 50
A
3.65
3.8
V
3/5 Comparator Output Low
I
LOAD
= 50
A
0.75
0.9
V
Off State Current at G1/G2
VPP1 = 10V, VG1 = 12V or VPP2 = 10V,
0.1
1
A
VG2 = 12V or V
ON/OFF
= 0V
T
A
= 25
C, V
CC
= 5V, V
ON/OFF
= 3V, unless otherwise noted.
ELECTRICAL C
C
HARA TERISTICS
The
q
denotes specifications which apply over the full operating
temperature range.
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
Oscillator Frequency
Switch Current Limit
Switch Saturation Voltage
TEMPERATURE (
C)
50
300
OSCILLATOR FREQUENCY (kHz) 400
500
600
700
800
25
0
25
50
LT1106 TPC01
75
100
TEMPERATURE (
C)
50
400
SWITCH CURRENT (mA)
500
600
700
800
1000
25
0
25
50
LT1106 TPC02
75
100
900
V
CC
= 3V
V
CC
= 5V
TEMPERATURE (
C)
50
100
SWITCH SATURATION VOLTAGE (mV)
125
150
175
200
250
25
0
25
50
LT1106 TPC03
75
100
225
I
SW
= 500mA
4
LT1106
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
3/ 5 Comparator Threshold
AVPP Sense Voltage
AVPP Sense Voltage
TEMPERATURE (
C)
50
3.70
THRESHOLD VOLTAGE (V)
3.75
3.80
3.85
3.90
4.00
25
0
25
50
LT1106 TPC04
75
100
3.95
TEMPERATURE (
C)
50
AVPP SENSE VOLTAGE (V)
11.95
12.00
12.05
25
75
LT1106 TPC05
11.90
11.85
11.80
25
0
50
12.10
12.15
12.20
100
12/5 SELECT = 0
TEMPERATURE (
C)
50
4.80
AVPP SENSE VOLTAGE (V)
4.85
4.90
4.95
5.00
5.10
25
0
25
50
LT1106 TPC06
75
100
5.05
12/5 SELECT = 1
Supply Current in Shutdown
TEMPERATURE (
C)
50
8
10
12
25
75
LT1106 TPC07
6
4
25
0
50
100
2
0
SUPPLY CURRENT (
A)
14
V
CC
= 5V
V
CC
= 3V
Supply Current
TEMPERATURE (
C)
50
300
SUPPLY CURRENT (
A)
400
500
600
700
800
25
0
25
50
LT1106 TPC08
75
100
V
CC
= 5V
V
CC
= 3V
TEMPERATURE (
C)
50
70
MAXIMUM DUTY CYCLE (%)
75
80
85
90
95
25
0
25
50
LT1106 TPC09
75
100
Load Transient Response,
C
OUT
= 1
F
LT1106 TPC12
50
s/DIV
12V OUTPUT
1V/DIV
AC COUPLED
60mA
10mA
I
LOAD
Start-Up Waveforms, I
LOAD
= 1mA
VAVPP
2V/DIV
12V
ON/OFF
10V/DIV
VPP VALID
10V/DIV
LT1106 TPC10
50
s/DIV
LT1106 TPC11
50
s/DIV
I
L
500mA/DIV
V
ON/OFF
10V/DIV
V
OUT
5V/DIV
Start-Up Waveforms with Soft
Start, I
LOAD
= 10mA
Maximum Duty Cycle
5
LT1106
PI FU CTIO S
U
U
U
SELECT 12/5 (Pin 1): Tie to V
IN
or logic 1 for 5V output;
tie to GND or logic 0 for 12V output.
SOFT START (Pin 2): A 0.1
F/1M
parallel RC from this
pin to GND provides a Soft Start function upon device
turn-on. Initially about 80
A will flow from the pin into the
capacitor. When the voltage at the pin reaches approxi-
mately 0.4V, current ceases flowing out of the pin. See
Applications Information section.
V
CC
(Pins 3, 4): Input Supply. Both pins should be tied
together. At least 1
F input bypass capacitance is re-
quired. More capacitance reduces ringing on the supply
line.
3/5 (Pin 5): Supply Comparator Output. This pin provides
logic output indicating the value of the input supply. High
when V
CC
= 5V; low when V
CC
= 3.3V.
PGND (Pins 6, 7): Power Ground. Connect to ground plane.
V
SW
(Pins 9, 10, 11): Collector of Power Switch. High dV/
dt present on this pin. To minimize radiated noise keep
layout short and direct.
GND (Pin 13): Signal Ground. Connect of ground plane.
VPP VALID (Pin 14): This pin provides a logic signal
indicating that ouput voltage is greater than 11.4V. Active
low with internal 200k pull-up resistor.
G1, G2 (Pins 16, 15): External MOSFET Gate Drives. When
VPP1 or VPP2 is greater than 11.7V, G1 or G2 is driven to
about 0.8V. When VPP1 or VPP2 is less than 11.7V, the
drives assume a high impedance state pulled up to the
AVPP pin through an internal 100k resistor.
VPP1, VPP2 (Pins 18, 17): Programming Power Inputs.
The LT1106 senses both VPP1 and VPP2 supplies at the
PCMCIA card socket. If VPP1 or VPP2 is greater than 11V,
the LT1106 operates in "Doze" Mode -- the switching
regulator turns off and the drive to external P-channel
MOSFETs turns on. Supply current in Doze Mode is about
350
A. Input current into VPP1 and VPP2 is about 1
A
when the device is shut down.
AVPP (Pin 19): Output Sense Pin. This pin connects to a
1M
resistive divider that sets the output voltage. In
shutdown, the resistor string is disconnected and current
into this pin is reduced to < 1
A.
ON/OFF (Pin 20): Shutdown Control. When pulled below
1.5V, this pin disables the LT1106 and reduces supply
current to 10
A. All circuitry except the 3/5 comparator
is disabled in shutdown. The part is enabled when
ON/OFF is greater than 1.5V.
6
LT1106
BLOCK DIAGRA
W
+
+
V
REF
V
CC
17
VPP2
20
BIAS
ON/0FF
16
14
G1
15
G2
18
VPP1
AVPP
12/5
SELECT
19
1
565k
299k
4k
200k
VPP VALID
OFF
Q3
Q2
1
Q1
50
100k
+
C2
V
REF
1.24V
R1
3
+
C3
36mV
V
CC
PGND
LT1106 BD
SW
R2
700
13
3,4
6,7
9,10,11
GND
2
SOFT START
BIAS
+
500kHz
OSCILLATOR
+
C1
5
3/5
V
CC
3.7V
+
APPLICATIO
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FOR
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ATIO
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Functional Description
The LT1106 is a micropower, step-up DC/DC converter
specifically configured for PCMCIA flash memory card
VPP generation. The device generates a 5V or 12V output
selectable via the 12/5 Select pin. If 12V is present on
either the VPP1 or VPP2 pins, gate drive outputs G1 and
G2 are driven low, turning on external PMOS devices. The
switching regulator inside the LT1106 is idled when 12V
is present on VPP1 or VPP2.
The VPP VALID output goes low when the voltage at AVPP
exceeds 11.4V This signal can be used to indicate pres-
ence of a valid programming voltage. The 3/5 comparator
indicates whether the input voltage is 3.3V or 5V.
The Soft Start pin can be used to limit inrush current upon
start-up. A 0.1
F capacitor in parallel with a 1M resistor is
connected between this pin and ground to limit peak
inductor current at start-up.
Switching Regulator Operation
When 12V is not present on the VPP1 or VPP2 pins and the
device is enabled (ON/OFF = 1), the LT1106 generates a
regulated voltage at the AVPP pin. This voltage is pro-
grammable between 5V or 12V depending on the state of
the 12/5 Select pin. Referring to the block diagram, hyster-
etic comparator C1 monitors AVPP via the resistor divider.
When the negative input of C2 falls below 1.24V, C1's
7
LT1106
output goes high, enabling the oscillator. Switch Q1
alternately turns on causing current build-up in the induc-
tor; then turns off allowing the built-up current to flow into
the output capacitor via the catch diode. As the output
voltage increases, so does the voltage at C1's negative
input. When it exceeds the reference voltage plus C1's
hysteresis, C1 turns the oscillator off.
Switch current is limited to approximately 600mA by Q2,
R1 and C3. Two percent of Q1's collector current flows in
Q2; this current flows through R1 causing a voltage drop
in R1 proportional to Q1's collector current. When R1's
drop equals 36mV, comparator C3 forces the oscillator
off. This action results in varying on-time, fixed off-time
operation that keeps peak switch current controlled. By
connecting a 0.1
F capacitor from the Soft Start pin to
ground, a current will flow in Q3 upon start-up. The current
flows through 700
resistor R2, reducing the amount of
current needed from Q2 to force the oscillator off. As
current flows into the 0.1
F capacitor, the voltage at pin 2
increases and eventually current ceases to flow in Q3.
Inductor Selection
All components for use in PCMCIA Type I cards must be
less than 1.1mm high. This somewhat limits the selection
of appropriate inductors. Dale Electronics (605-665-9301)
manufactures the ILS-3825-01, a monolithic ferrite induc-
tor that meets Type I height requirements. Generally,
inductors used with the LT1106 must fulfill several re-
quirements. It must be able to carry 0.95A (the maximum
switch current) without saturation. DCR should be kept
low to maintain efficiency. The switching frequency of the
LT1106 is quite high, over 500kHz so magnetic material is
important. Ferrite core material works well in this fre-
quency range. Avoid low cost iron powder cores which
APPLICATIO
N
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FOR
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ATIO
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have substantial AC loss at the LT1106's switching fre-
quency. Inductance value need not be over 10
H.
Capacitor Selection
The LT1106 will operate with 1
F of output capacitance.
Output ripple voltage is approximately 400mV with this
value and can be reduced significantly by increasing
output capacitance. The ripple voltage, although on the
high side, poses no problems for programming flash
memory. If operating the device in 5V ouput mode the
capacitance should be increased. Ceramic capacitors are
suitable for the output. Distributed capacitance, i.e.,
0.1
F or 0.2
F units next to individual flash memory
chips, is acceptable. The input capacitor should have at
least some tantalum capacitance (low Q) to minimize
resonance on the input. Flash memory cards are typically
several inches away from a solid low impedance supply
due to sockets, connectors, etc. If just ceramic capaci-
tors are used at the supply pin of the LT1106, switching
currents will resonate the supply line causing ringing that
can exceed 500mV
P-P
. The high Q, low ESR nature of
ceramic capacitors causes this. A few microfarad's worth
of tantalum capacitors with moderate ESR and low Q
characteristics will reduce or eliminate the problem.
Diode Selection
As with inductors, most good power Schottky diodes are
in packages that exceed the 1.1mm height limit of the
Type I PCMCIA card. Motorola manufactures the MBRO530
Schottky diode, ideal for use with the LT1106. This
diode's maximum height however, is 1.35mm, making it
difficult to use in Type 1 cards. Philips Components
manufactures the BAT54C. Four units in parallel make an
adequate diode.
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
8
LT1106
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900
q
FAX
: (408) 434-0507
q
TELEX
: 499-3977
LINEAR TECHNOLOGY CORPORATION 1995
LT/GP 0595 10K PRINTED IN THE USA
TYPICAL APPLICATIO
N
U
Alternative Scheme Allows 12V from VPP1/VPP2 to Provide Power When LT1106 is in Shutdown
V
CC
ON/OFF
SEL
PGND
SW
POWER ON
DALE ILS-3824-01
MBR0530 OR 4 BAT54s IN PARALLEL
*
**
LT1106 TA03
GND
SOFT START
AVPP
VPP2
VPP1
1M
0.1
F
VPP VALID
1
F
D**
D**
D**
L1*
10
H
4.7
F
V
CC
3.3V/5V
LT1106
VPP VALID
12V/60mA
470pF
+
Dimensions in inches (millimeters) unless otherwise noted.
F Package
20-Lead Plastic TSSOP
F20 TSSOP 0395
0.004 0.071
(0.09 0.18)
0
8
0.020 0.028
(0.50 0.70)
0.169 0.176*
(4.30 4.48)
0.043
(1.10)
MAX
0.002 0.006
(0.05 0.15)
0.0256
(0.65)
BSC
0.007 0.012
(0.18 0.30)
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm).
0.246 0.256
(6.25 6.50)
1
3
4
5
6 7 8
9 10
11
12
14 13
0.252 0.260*
(6.40 6.60)
20 19 18 17 16 15
2
PACKAGE DESCRIPTIO
N
U
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1109
5V to 12V/60mA VPP Generator
300
A I
Q
, 120kHz Oscillator
LT1109A
5V to 12V/120mA VPP Generator
300
A I
Q
, 120kHz Oscillator
LT1301
5V to 12V/200mA VPP Generator
120
A I
Q
, 155kHz Oscillator
LT1309
5V to 12V/60mA VPP Generator
650
A I
Q
, 650kHz Oscillator
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