LT3473/LT3473A
Micropower 1A Boost
Converter with Schottky
and Output Disconnect
U
FEATURES
DESCRIPTIO
The LT®3473/LT3473A are micropower step-up DC/DC
converters with integrated Schottky diode and output
disconnect circuitry in low profile DFN packages. The
small package size, high level of integration and the use of
tiny SMT components yield a solution size of less than
50mm2. Theinternal1Aswitchallowsthedevicetodeliver
25Vatupto80mAfromaLi-Ioncell,whileautomaticBurst
Mode operation maintains efficiency at light load. An
auxiliary reference input (CTRL) allows the user to over-
ride the internal 1.25V feedback reference with any lower
value, allowing full control of the output voltage during
operation. A PGOOD pin sinks current when the output
voltage reaches 90% of final value.
■
Tiny Solution Size
Low Quiescent Current:
■
150µA in Active Mode (VIN = 3.6V, VOUT = 15V,
No Load)
1µA in Shutdown Mode
■
Internal 1A, 36V Switch
■
Integrated Schottky Diode
■
Integrated PNP Output Disconnect
■
Internal Reference Override Pin
■
PGOOD Pin
■
25V at 80mA from 3.6V Input
■
Auxiliary NPNs for Intermediate
Bias Voltages (LT3473A)
Automatic Burst Mode® Operation at Light Load
■
TheLT3473AincludestwoNPNtransistorsforgenerating
intermediate bias voltages from the output and is offered
in a 12-lead (4mm × 3mm) DFN package. The LT3473
does not include these NPNs and is offered in an 8-lead
(3mm × 3mm) package.
■
Constant Switching Frequency: 1.2MHz
Thermal Shutdown
Input Range: 2.2V to 16V
■
■
■
Low Profile (3mm × 3mm) DFN Package (LT3473)
Low Profile (4mm × 3mm) DFN Package (LT3473A)
■
U
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.
Burst Mode is a registered trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
APPLICATIO S
■
OLED Bias
CCD Bias
■
U
TYPICAL APPLICATIO
Conversion Efficiency and Power Loss vs Output Current
80
75
70
65
60
55
500
400
300
200
100
0
V
V
= 3.6V
OUT
IN
= 15V
V
OUT
25V
PGOOD
CTRL
OUT
80mA
2.2µF
6.8µH
LT3473
V
IN
3V TO 4.2V
SW
CAP
FB
V
IN
2M
0.47µF
SHDN
100k
GND
4.7µF
3473 TA01a
0.1
1
10
OUTPUT CURRENT (mA)
100
3473 TA01b
3473f
1