FEATURES
s Wide Input Voltage Range: 3.2V to 34V
s Micropower Operation: IQ = 12µA
s 5V at 250mA from 6.5V to 34V Input (LT1934)
s 5V at 60mA from 6.5V to 34V Input (LT1934-1)
s 3.3V at 250mA from 4.5V to 34V Input (LT1934)
s 3.3V at 60mA from 4.5V to 34V Input (LT1934-1)
s Low Shutdown Current: <1µA
s Low VCESAT Switch: 200mV at 300mA
s Low Profile (1mm) SOT-23 (ThinSOTTM) Package
U
APPLICATIO S
s Wall Transformer Regulation
s Automotive Battery Regulation
s Standby Power for Portable Products
s Distributed Supply Regulation
s Industrial Control Supplies
LT19w3ww4.D/atLaTSh1ee9t4U3.c4om-1
Micropower Step-Down
Switching Regulators
in ThinSOT
DESCRIPTIO
The LT®1934 is a micropower step-down DC/DC con-
verter 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 bat-
teries. Quiescent current is just 12µA and a zero current
shutdown mode disconnects the load from the input
source, simplifying power management in battery-pow-
ered systems. 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.
, LTC and LT 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.
TYPICAL APPLICATIO
3.3V Step-Down Converter
D2
VIN
4.5V TO 34V
C2
2.2µF
ON OFF
BOOST
VIN SW
LT1934
SHDN
FB
GND
0.22µF L1
47µH
D1
10pF 1M +
604k
VOUT
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
VIN = 12V
90
80
70
Efficiency
VOUT = 5V
VOUT = 3.3V
60
50
0.1
1 10 100
LOAD CURRENT (mA)
1934 TA02
1934f
1
