LT3464
Micropower Boost
Converter with Schottky and
Output Disconnect in ThinSOT™
FEATURES
s
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DESCRIPTIO
s
s
s
s
s
s
s
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Tiny Solution Size
Low Quiescent Current
•
25µA in Active Mode
•
0.5µA in Shutdown Mode
Internal 115mA, 36V Switch
Integrated Schottky Diode
Integrated PNP Output Disconnect with
Short-Circuit Protection
Internal Reference Override Pin
16V at 8mA from 3.6V Input
12V at 20mA from 5V Input
Input Range: 2.3V to 10V
High Output Voltage: Up to 34V
Low Profile (1mm) SOT-23 Package
APPLICATIO S
s
s
s
s
s
s
OEL Panel Bias
LCD Bias
Handheld Computers
Battery Backup
Digital Cameras
Cellular Phones
The LT
®
3464 is a micropower step-up DC/DC converter
with integrated Schottky diode and output disconnect
packaged in an 8-lead low profile (1mm) SOT-23. The
small package size, high level of integration, and the use
of tiny SMT components yield a solution size of less than
40mm
2
. The LT3464 has a typical current limit of 115mA
as well as fast switching speed to allow the use of a chip
inductor and small ceramic capacitors. The internal PNP
disconnects the output load from the input during shut-
down, and also provides output short-circuit protection.
An auxiliary reference input allows the user to override the
internal 1.25V feedback reference with any lower value,
allowing full control of the output voltage during opera-
tion. This device features a low 25
µA
quiescent current,
which is further reduced to less than 0.5µA in shutdown.
A current limited fixed off-time control scheme conserves
operating current, resulting in high efficiency over a broad
range of operating current. The rugged 36V switch and
output disconnect circuitry allow outputs up to 34V to be
easily generated in a simple boost topology.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technolgy Corporation
TYPICAL APPLICATIO
V
IN
2.3V TO 10V
V
IN
CTRL
22µH
90
80
V
IN
= 8.4V
V
IN
= 4.2V
SW
OUT
0.22µF
LT3464
CAP
0.33µF
FB
GND
3464 TA01a
1µF
EFFICIENCY (%)
V
OUT
16V
70
60
50
40
30
0.01
SHDN
3.48M
294k
U
Efficiency
0.1
1
10
LOAD CURRENT (mA)
100
3464 TA01b
U
U
3464f
1
LT3464
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
CTRL 1
FB 2
OUT 3
GND 4
8 SHDN
7 V
IN
6 SW
5 CAP
V
IN
, SHDN, CTRL Voltage ........................................ 10V
OUT, CAP Voltage .................................................... 36V
SW Voltage .............................................................. 36V
FB Voltage ................................................................. 6V
Maximum Junction Temperature .......................... 125°C
Operating Temperature Range (Note 2) .. – 40°C to 85°C
Storage Temperature Range ..................–65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LT3464ETS8
TS8 PART MARKING
LTG2
TS8 PACKAGE
8-LEAD PLASTIC SOT-23
T
JMAX
= 125°C,
θ
JA
= 140°C/W,
θ
JC
= 85°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V, unless otherwise noted. (Note 2)
PARAMETER
Minimum Input Voltage
Quiescent Current
FB Comparator Trip Voltage
FB Comparator Hysteresis
FB Pin Bias Current
FB Voltage Line Regulation
Switch Off Time
Switch Leakage Current
Switch V
CESAT
Switch Current Limit
Schottky Forward Voltage
Schottky Reverse Leakage
PNP Disconnect V
CAP-OUT
PNP Disconnect Q Current
PNP Disconnect Leakage
PNP Disconnect Current Limit
SHDN Pin Current
SHDN Input Voltage High
SHDN Input Voltage Low
CTRL Pin Bias Current
CTRL to FB Offset
V
CTRL
= 0.5V, V
FB
= 1V
V
CTRL
= 0.5V (Note 4)
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
Not Switching
V
SHDN
= 0.2V
V
FB
Falling, V
CTRL
= 3.6V
V
FB
= 1.25V, V
CTRL
= 3.6V
2.3V < V
IN
< 10V
V
CAP
-V
IN
= 5V
V
CAP
-V
IN
= 0V
V
SW
= 36V
I
SW
= 80mA
q
MIN
TYP
2.0
25
0.01
MAX
2.3
36
0.5
1.275
30
0.1
UNITS
V
µA
µA
V
mV
nA
%/V
ns
µs
1.215
1.250
10
3
0.05
250
1.0
0.02
190
q
1
300
140
750
10
85
I
SCHOTTKY
= 110mA
V
CAP-SW
= 36V
I
OUT
= 200µA
I
OUT
= 10mA
I
OUT
= 0, V
CAP
= 36V (Note 3)
SHDN = 0.2, V
CAP
= 10V, V
OUT
= 0V
V
CAP
= 10V, V
OUT
= 0V
V
SHDN
= 3.6V
2.3
25
115
600
1
100
190
1.5
0.1
45
5
5
5
75
10
0.2
6
2
80
7
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
The LT3464E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the – 40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3:
Current consumed by Disconnect PNP when there is no load on
the OUT pin.
Note 4:
This figure is computed according to ((V
FB
falling + V
FB
rising)/2)
–V
CONTROL
.
2
U
µA
mV
mA
mV
µA
mV
mV
µA
µA
mA
µA
V
V
nA
mV
3464f
W
U
U
W W
W
LT3464
TYPICAL PERFOR A CE CHARACTERISTICS
Switch Saturation Voltage
I
SW
= 80mA
220
200
SWITCH CURRENT (mA)
SWITCH VOLTAGE (mV)
180
160
140
120
100
–50
SWITCH OFF-TIME (ns)
–25
0
25
50
TEMPERATURE (°C)
Minimum Switch On-Time
100
90
80
SWITCH OFF-TIME (µs)
SWITCH ON-TIME (ns)
70
60
50
40
30
20
10
0
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G04
VOLTAGE DROP (mV)
Output Disconnect Quiescent
Current
2.0
1.8
QUIESCENT CURRENT (µA)
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G07
CURRENT LIMIT (mA)
40
30
20
10
0
–50
VOLTAGE DROP (mV)
U W
75
100
3464 G01
Switch Current Limit
140
120
100
80
60
40
20
0
–50
400
350
300
250
200
150
100
50
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G02
Switch Off-Time, V
CAP
– V
IN
= 5V
0
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G03
Switch Off-Time, V
CAP
– V
IN
= 0V
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G05
Output Disconnect Voltage Drop
300
250
I
OUT
= 10mA
200
150
100
50
0
–50
I
OUT
= 200µA
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G06
Output Disconnect Current Limit
60
50
300
250
200
150
100
50
0
Output Disconnect Voltage Drop
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G08
0
10
20
COLLECTOR CURRENT (mA)
30
3464 G09
3464f
3
LT3464
TYPICAL PERFOR A CE CHARACTERISTICS
Schottky Forward Drop
at I
D
= 110mA
800
750
SCHOTTKY CURRENT (mA)
LEAKAGE CURRENT (µA)
700
VOLTAGE DROP (mV)
650
600
550
500
450
400
350
300
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G10
Quiescent Current
30
28
QUIESCENT CURRENT (µA)
SHUTDOWN PIN CURRENT (µA)
QUIESCENT CURRENT (nA)
26
24
22
20
18
16
14
12
10
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G12
Quiescent Current in
Regulation with No Load
70
60
QUIESCENT CURRENT (µA)
FB PIN VOLTAGE (V)
50
40
30
20
10
0
6
V
IN
= 5V
FRONT PAGE SCHEMATIC
8
10
14
12
V
OUT
(V)
16
18
20
SHDN PIN VOLTAGE (V)
4
U W
3464
G18
Schottky Forward Voltage
250
20
Schottky Reverse Leakage
V
CAP
– SW = 36V
200
16
150
12
100
8
50
4
0
200
300
400
500
600
700
FORWARD VOLTAGE (mV)
800
3464 G11
0
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G20
Shutdown Pin Current
V
SHDN
= 3.6V
12
10
8
6
4
2
0
–50
16
14
12
10
8
6
4
2
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G13
Quiescent Current in
Shutdown Mode
0
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G14
SHDN Pin Threshold Voltage
3.0
2.8
2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G15
FB Pin Voltage
1.30
1.28
1.26
1.24
1.22
1.20
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G16
3464f
LT3464
TYPICAL PERFOR A CE CHARACTERISTICS
FB Pin Voltage vs
CTRL Pin Voltage
1.50
1.25
8
7
CTRL PIN
FB PIN VOLTAGE (V)
HYSTERESIS (mV)
75
100
3464 G18
1.00
0.75
0.50
0.25
0
BIAS CURRENT (nA)
0
0.25
0.5 0.75 1.0 1.25 1.5
CONTROL PIN VOLTAGE (V)
PI FU CTIO S
CTRL (Pin 1):
Internal Reference Override Pin. This allows
the FB voltage to be externally set between 0V and 1.25V.
Tie this pin to above 1.5V (V
IN
for example) to use the
internal 1.25V reference.
V
OUT
R2
=
V
CTRL
+
1
R1
when V
CTRL
is less than 1.25V (see Figure 4)
FB (Pin 2):
Feedback Pin. The LT3464 regulates its feed-
back pin to 1.25V if the internal reference is used or to
V
CTRL
if the CTRL pin is between 0V and 1.25V. Connect
the feedback resistor divider tap to this pin. Set the output
voltage by selecting R1 and R2 (see Figure 4).
V
R2
=
R1
OUT
– 1
V
REF
OUT (Pin 3):
PNP Collector. This is the output of the
Output Disconnect circuit. Bypass this pin with at least a
0.1µF capacitor connected to the CAP pin or to ground.
U W
3464 G17
FB and CTRL Pin
Bias Currents
12
10
8
6
4
2
FB Pin Hysteresis
6
5
4
3
2
1
FEEDBACK PIN
1.75
0
–50
–25
0
25
50
TEMPERATURE (°C)
0
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
3464 G19
U
U
U
GND (Pin 4):
Ground. Tie this pin directly to the ground
plane.
CAP (Pin 5):
PNP Emitter and Schottky Cathode. This pin
connects to the output capacitor, and optionally to the
external phase-lead capacitor.
SW (Pin 6):
Switch Pin and Schottky Anode. This is the
collector of the internal NPN power switch. Minimize the
metal trace area connected to the pin to minimize EMI.
V
IN
(Pin 7):
Input Supply Pin: Bypass this pin with a
capacitor located as close to the device as possible.
SHDN (Pin 8):
Shutdown Pin. This pin is used to put the
device in shutdown mode. Tie the pin low to shut down the
LT3464. Tie high for normal operation See the electrical
specifications for the required voltages.
3464f
5
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