LTC3256
Wide V Range
IN
Dual Output 350mA Step-Down
Charge Pump with Watchdog Timer
Fea T Descrip T
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Input Voltage Range: 5.5V to 38V The LTC 3256 is a wide input range switched capacitor
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Independently Enabled 5V and 3.3V Fixed Outputs step-down DC/DC converter that produces two regulated
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5V Output: 100mA Max outputs: a 5V output via direct connection to the charge
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3.3V LDO Output: 250mA Max pump output, and a 3.3V output via a low dropout (LDO)
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Multimode Step-Down Charge Pump (2:1, 1:1) with linear post-regulator. The device provides up to 350mA
Automatic Mode Switching of total output current. At 12V V and maximum load on
IN
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Low Quiescent Current both outputs, power dissipation is reduced by over 2W
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20A with Both Outputs Regulating (No Load) compared to a dual LDO regulator solution.
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0.5A in Shutdown
The LTC3256 maximizes efficiency by running the charge
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Engineered for Diagnostic Coverage in
pump in 2:1 mode over as wide an operating range as pos-
ISO26262Systems
sible, and automatically switches to 1:1 mode as needed
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1.1V Reference Output for System Diagnostics
due to V and load conditions. Controlled input current and
IN
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Power-On Reset and Watchdog Controller with
switching slew rates minimize conducted and radiated EMI.
Adjustable Timing
An integrated watchdog timer, independent power good
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Overcurrent Fault Protection on Each Output
outputs and reset input ensure reliable system operation
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Overtemperature Protection
and fault monitoring. A buffered 1.1V reference output
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150C Max Operating Junction Temperature
enables system self-testing for safety critical applications.
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Thermally Enhanced 16-Lead MSOP Package
The LTC3256 has numerous safety features including
overcurrent fault protection, overtemperature protection
a T
and tolerance of 38V input transients. The LTC3256 is
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Automotive ECU/CAN Transceiver Supplies available in a thermally enhanced 16-lead MSOP plastic
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Industrial/Telecom Housekeeping Supplies package with exposed pad (MSE16).
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Low Power 12V to 5V and 3.3V Conversion L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners.
Typical a T
High Efficiency Dual Output Power Supply Power Dissipation vs Input Voltage
5.0
3.3V LOAD = 250mA
4.5
10F
1F
5V LOAD = 100mA
4.0
+
OUTCP C C
3.5
RT
OUT5 5V OUTPUT
WT 3.0
100mA MAX
10F
IDEAL DUAL LDO
2.5
5.5V TO 38V
V OUT3 3.3V LDO OUTPUT 2.0
IN
INPUT SUPPLY LTC3256
250mA MAX
10F
1M
1.5
EN5 PG5 1.0
10F EN3 PG3 LTC3256
0.5
RSTI
RST
0.0
MICROCONTROLLER
WDI
6 7 8 9 10 11 12 13 14 15 16
INTERFACE
REFOUT
GND
INPUT VOLTAGE (V)
3256 TA01
0.1F
3256 TA01a
3256fb
1
For more information www.linear.com/LTC3256
POWER DISSIPATION (W)
ion pplica
ions pplica
ion uresLTC3256
a Te Maxi Mu M r a T p c F T
(Notes 1, 2)
TOP VIEW
V , EN3, EN5, WDI .................................... 0.3V to 38V
IN
C 1 16 EN5
OUTCP, OUT3, OUT5 ................................. 0.3V to 5.5V
+
2 15 EN3
C
OUTCP 3 14 V
OUT3, OUT5 Short Circuit Duration ................. Indefinite IN
17
4 13
OUT5 WDI
GND
REFOUT 5 12 RSTI
PG3, PG5, REFOUT ............................... 0.3V to V
OUTCP
6 11 RT
OUT3
RST ........................................................... 0.3V to 5.5V PG3 7 10 WT
8 9 RST
PG5
WT, RT .................................................. 0.3V to V
OUTCP
MS PACKAGE
RSTI ......................................................... 0.3V to 5.5V 16-LEAD PLASTIC MSOP
T = 150C, = 10C/W
JMAX JC
Operating Junction Temperature Range (Notes 3, 4)
= 40C/W
JA
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
LTC3256E .......................................... 40C to 125C
LTC3256I ........................................... 40C to 125C
LTC3256H .......................................... 40C to 150C
LTC3256MP ....................................... 55C to 150C
Storage Temperature Range .................. 65C to 150C
Lead Temperature (Soldering, 10 sec) ...................300C
o r D i n F Ma T