LT3494 Datasheet, PDF (1/12 Pages) Linear Technology – Micropower Low Noise Boost Converters with Output Disconnect

FEATURES
■ _{Low Quiescent Current}
65μA in Active Mode
1μA in Shutdown Mode
■ _{Switching Frequency is Non-Audible Over Entire}
Load Range
■ _{Integrated Power NPN:}
350mA Current Limit (LT3494A)
180mA Current Limit (LT3494)
■ _{Integrated Schottky Diode}
■ _{Integrated Output Disconnect}
■ _{Integrated Output Dimming}
■ _{Wide Input Range: 2.3V to 16V}
■ _{Wide Output Range: Up to 40V}
■ _{Tiny 8-Lead 3mm × 2mm DFN Package}
APPLICATIONS
■ _{OLED Power}
■ _{Low Noise Power}
■ _{MP3 Players}
LT3494/LT3494A
Micropower Low Noise
Boost Converters with
Output Disconnect
DESCRIPTION
The LT^®3494/LT3494A are low noise boost converters
with integrated power switch, Schottky diode and output
disconnect circuitry. The parts use a novel* control tech-
nique resulting in low output voltage ripple as well as high
efficiency over a wide load current range. This technique
guarantees that the switching frequency stays above the
audio band for the entire load range. The parts feature a high
performance NPN power switch with a 350mA and 180mA
current limit for the LT3494A and LT3494 respectively. The
quiescent current is a low 65μA, which is further reduced
to less than 1μA in shutdown. The internal disconnect
circuitry allows the output voltage to be isolated from the
input during shutdown. An auxiliary reference input (CTRL
pin) overrides the internal 1.225V feedback reference with
any lower value allowing full control of the output voltage
during operation. The LT3494/LT3494A are available in a
tiny 8-lead 3mm × 2mm DFN package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
*Patent pending.
TYPICAL APPLICATION
OLED Power Supply from One Li-Ion Cell
V_IN
3V
TO 4.2V
15μH
4.7μF
SW CAP
V_CC V_OUT
LT3494
SHDN FB
CTRL GND
0.22μF
2.21M
V_OUT
16V
16mA
2.2μF
3494 TA01a
Output Voltage Ripple
vs Load Current
15
LT3494
FIGURE 5 CIRCUIT
100MHz MEASUREMENT BW
10
5
0
0.1
1
10
LOAD CURRENT (mA)
100
3494 TA01b
Efficiency and Power Loss
vs Load Current
90
280
V_IN = 3.6V
LOAD FROM
80
CAPACITOR
240
70
LOAD FROM
200
V_OUT
60
160
50
120
40
80
30
40
20
0.1
1
10
LOAD CURRENT (mA)
0
100
3494 TA01c
3494fb
1