1
dc2041af
DEMO MANUAL DC2041A
Description
LTC3255EMSE
Wide V
IN
Range Fault Protected
50mA Step-Down Charge Pump
Demonstration circuit 2041A is a switched-capacitor
step-down power supply featuring the
. The
LTC3255 has the ability to step down voltage 2:1 to ef-
ficiently regulate output voltages less than half the V
IN
voltage reducing the input current needed. As V
IN
reduces
below twice V
OUT
, the LTC3255 will automatically switch
to 1:1 mode.
The LTC3255 also has an integrated shunt regulator al-
lowing it to provide a regulated output from a 4mA to
20mA current loop.
L
, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
performance summary
The LTC3255 is a robust device that can survive reverse-
polarity input supplies with current limit and overtem-
perature protection.
Refer to the LTC3255 data sheet for more details on the
electrical and timing specifications.
Design files for this circuit board are available at
Specifications are at T
A
= 25°C
7.4mA DC Supply from 4mA to 20mA Current Loop
Available Output Current
vs Input Current
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Input Supply Range
4
48
V
V
OUT
2.4
12.5
V
I
OUT
Shunt Jumper = OFF (SHUNT = GND)
Shunt Jumper = ON (SHUNT = BIAS) I
IN
= 4mA
50
7.4
7.8
mA
mA
V
IN
EN
220k
10µF
DC2041A F01
0.1µF
4mA TO 20mA INPUT
>10V COMPLIANCE
1µF
1µF
OUTPUT
3.3V
7.4mA
LTC3255
GND
C
+
C
–
SHUNT
BIAS
PGOOD
+
–
PGOOD
FB
V
OUT
2.15M
1.21M
4
8
12
14
20
6
10
16
18
INPUT CURRENT (mA)
AVAILABLE OUTPUT CURRENT (mA)
16
31
34
37
40
10
25
13
28
7
4
22
19
DC2041A F02
INCREASED
I
OUT
CAPABILITY
AVAILABLE
I
OUT
INPUT
CURRENT
