LT1317B_15 Datasheet, PDF (1/16 Pages) Linear Technology – Micropower, 600kHz PWM DC/DC Converters

LT1317/LT1317B
Micropower, 600kHz PWM
DC/DC Converters
FEATURES
s _{100µA Quiescent Current}
s _{Operates with VIN as Low as 1.5V}
s _{600kHz Fixed Frequency Operation}
s _{Starts into Full Load}
s _{Low-Battery Detector Active in Shutdown}
s _{Automatic Burst Mode Operation at}
Light Load (LT1317)
s _{Continuous Switching at Light Loads (LT1317B)}
s _{Low VCESAT Switch: 300mV at 500mA}
s _{Pin for Pin Compatible with the LT1307/LT1307B}
U
APPLICATIONS
s _{Cellular Telephones}
s _{Cordless Telephones}
s _Pagers
s _{GPS Receivers}
s _{Battery Backup}
s _{Portable Electronic Equipment}
s _{Glucose Meters}
s _{Diagnostic Medical Instrumentation}
TYPICAL APPLICATION
L1
10µH
D1
+
C1
47µF
2
SHUTDOWN
CELLS
V_IN
SW
LBI
FB
LT1317
SHDN
LBO
V_C
GND
R_C
33k
C_C
3.3nF
R1
1M
1% ₊
R2*
604k
1%
3.3V
200mA
C2
47µF
D1: MBR0520
L1: SUMIDA CD43-100
* FOR 5V OUTPUT, R2 = 332k, 1%
1317 F01
Figure 1. 2-Cell to 3.3V Boost Converter
DESCRIPTION
The LT^®1317/LT1317B are micropower, fixed frequency
step-up DC/DC converters that operate over a wide input
voltage range of 1.5V to 12V. The LT1317 features auto-
matic shifting to power saving Burst Mode^TM operation at
light loads. High efficiency is maintained over a broad
300µA to 200mA load range. Peak switch current during
Burst Mode operation is kept below 250mA for most
operating conditions which results in low output ripple
voltage, even at high input voltages. The LT1317B does
not shift into Burst Mode operation at light loads, eliminat-
ing low frequency output ripple at the expense of light load
efficiency.
The LT1317/LT1317B contain an internal low-battery de-
tector with a 200mV reference that stays alive when the
device goes into shutdown.
No-load quiescent current of the LT1317 is 100µA and
shuts down to 30µA. The internal NPN power switch
handles a 500mA current with a voltage drop of just
300mV.
The LT1317/LT1317B are available in MS8 and SO-8
packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
2-Cell to 3.3V Converter Efficiency
90
2.2V_IN 3V_IN
80
1.65V_IN
70
60
50
40
0.3 1
10
100
LOAD CURRENT (mA)
1000
1317 TA01
1