LT1934_15 Datasheet, PDF (1/20 Pages) Linear Technology – Micropower Step-Down Switching Regulators in ThinSOT and DFN

FEATURES
n _{Wide Input Voltage Range: 3.2V to 34V}
n _{Micropower Operation: IQ = 12μA}
n _{5V at 250mA from 6.5V to 34V Input (LT1934)}
n _{5V at 60mA from 6.5V to 34V Input (LT1934-1)}
n _{3.3V at 250mA from 4.5V to 34V Input (LT1934)}
n _{3.3V at 60mA from 4.5V to 34V Input (LT1934-1)}
n _{Low Shutdown Current: <1μA}
n _{Low VCESAT Switch: 200mV at 300mA}
n _{Low Profile (1mm) SOT-23 (ThinSOT™) and}
(2mm × 3mm × 0.8mm) 6-Pin DFN Package
APPLICATIONS
n _{Wall Transformer Regulation}
n _{Automotive Battery Regulation}
n _{Standby Power for Portable Products}
n _{Distributed Supply Regulation}
n _{Industrial Control Supplies}
LT1934/LT1934-1
Micropower Step-Down
Switching Regulators
in ThinSOT and DFN
DESCRIPTION
The LT^®1934 is a micropower step-down DC/DC converter
with internal 400mA power switch, packaged in a low
profile (1mm) ThinSOT. With its wide input range of 3.2V
to 34V, the LT1934 can regulate a wide variety of power
sources, from 4-cell alkaline batteries and 5V logic rails
to unregulated wall transformers and lead-acid batteries.
Quiescent current is just 12μA and a zero current shut-
down mode disconnects the load from the input source,
simplifying power management in battery-powered sys-
tems. Burst Mode^® operation and the low drop internal
power switch result in high efficiency over a broad range
of load current.
The LT1934 provides up to 300mA of output current. The
LT1934-1 has a lower current limit, allowing optimum
choice of external components when the required output
current is less than 60mA. Fast current limiting protects
the LT1934 and external components against shorted
outputs, even at 34V input.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
3.3V Step-Down Converter
D2
V_IN
4.5V TO 34V
C2
2.2μF
ON OFF
BOOST
V_IN
SW
LT1934
SHDN
FB
GND
0.22μF
L1
47μH
D1
10pF 1M ₊
604k
V_OUT
3.3V
250mA
C1
100μF
C1: SANYO 4TPB100M
C2: TAIYO YUDEN GMK325BJ225MN
D1: ON SEMICONDUCTOR MBR0540
D2: CENTRAL CMDSH-3
L1: SUMIDA CDRH4D28-470
1934 TA01
100
LT1934
V_IN = 12V
90
80
70
Efficiency
V_OUT = 5V
V_OUT = 3.3V
60
50
0.1
1
10
100
LOAD CURRENT (mA)
1934 TA02
1934fe
1