and tolerance of 38V input transients. The LTC3256 is
available in a thermally enhanced 16-lead MSOP plastic
package with exposed pad (MSE16).
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.
n
n
n
n
n
n
n
n
Input Voltage Range: 5.5V to 38V
Independently Enabled 5V and 3.3V Fixed Outputs
5V Output: 100mA Max
3.3V LDO Output: 250mA Max
Multimode Step-Down Charge Pump (2:1, 1:1) with
Automatic Mode Switching
Low Quiescent Current
n
20μA with Both Outputs Regulating (No Load)
n
0.5μA in Shutdown
Engineered for Diagnostic Coverage in
ISO26262 Systems
1.1V Reference Output for System Diagnostics
Power-On Reset and Watchdog Controller with
Adjustable Timing
Overcurrent Fault Protection on Each Output
Overtemperature Protection
150°C Max Operating Junction Temperature
Thermally Enhanced 16-Lead MSOP Package
applicaTions
n
n
n
Automotive ECU/CAN Transceiver Supplies
Industrial/Telecom Housekeeping Supplies
Low Power 12V to 5V and 3.3V Conversion
Typical applicaTion
High Efficiency Dual Output Power Supply
10µF
OUTCP
RT
WT
5.5V TO 38V
INPUT SUPPLY
V
IN
EN5
EN3
C
+
1µF
POWER DISSIPATION (W)
C
–
OUT5
5V OUTPUT
10µF 100mA MAX
3.3V LDO OUTPUT
10µF 250mA MAX
Power Dissipation vs Input Voltage
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
LTC3256
IDEAL DUAL LDO
3.3V LOAD = 250mA
5V LOAD = 100mA
LTC3256
OUT3
1M
PG5
PG3
RSTI
RST
WDI
REFOUT
3256 TA01
10µF
GND
MICROCONTROLLER
INTERFACE
0.1µF
0.0
6
7
8
9
10 11 12 13 14 15 16
3256 TA01a
INPUT VOLTAGE (V)
3256fb
For more information
www.linear.com/LTC3256
1
LTC3256
absoluTe MaxiMuM raTings
(Notes 1, 2)
pin conFiguraTion
TOP VIEW
C
–
1
C
+
2
3
4
5
6
7
8
17
GND
16
15
14
13
12
11
10
9
EN5
EN3
V
IN
WDI
RSTI
RT
WT
RST
V
IN
, EN3, EN5, WDI .................................... –0.3V to 38V
OUTCP, OUT3, OUT5 ................................. –0.3V to 5.5V
OUT3, OUT5 Short Circuit Duration ................. Indefinite
PG3, PG5, REFOUT ............................... –0.3V to V
OUTCP
RST
........................................................... –0.3V to 5.5V
WT, RT .................................................. –0.3V to V
OUTCP
RSTI ......................................................... –0.3V to 5.5V
Operating Junction Temperature Range (Notes 3, 4)
LTC3256E .......................................... –40°C to 125°C
LTC3256I ........................................... –40°C to 125°C
LTC3256H .......................................... –40°C to 150°C
LTC3256MP ....................................... –55°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
OUTCP
OUT5
REFOUT
OUT3
PG3
PG5
MS PACKAGE
16-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JC
= 10°C/W
θ
JA
= 40°C/W
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH
LTC3256EMSE#PBF
LTC3256IMSE#PBF
LTC3256HMSE#PBF
LTC3256MPMSE#PBF
TAPE AND REEL
LTC3256EMSE#TRPBF
LTC3256IMSE#TRPBF
LTC3256HMSE#TRPBF
http://www.linear.com/product/LTC3256#orderinfo
PART MARKING*
3256
3256
3256
3256
PACKAGE DESCRIPTION
16-Lead Plastic MSOP
16-Lead Plastic MSOP
16-Lead Plastic MSOP
16-Lead Plastic MSOP
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
–55°C to 150°C
LTC3256MPMSE#TRPBF
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
2
3256fb
For more information
www.linear.com/LTC3256
LTC3256
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 3). V
IN
= 12V, C
FLY
= 1µF unless otherwise noted.
SYMBOL
V
IN
PARAMETER
Operating Input Voltage Range (Note 5)
V
IN
Undervoltage Lockout Threshold
V
IN
Quiescent Current
EN5 = EN3 = 0V
Only One Output Enabled
Both OUT3 and OUT5 Enabled
EN3, EN5 Input High Voltage
EN3, EN5 Input Low Voltage
EN3, EN5 Input Low Current
EN3, EN5 Input High Current
Charge Pump Operation
V
OUTCP
OUTCP Regulation Voltage
OUTCP Short Circuit Current
Charge Pump Output Impedance
5V Output Operation
V
OUT5
Fixed 5V Output Regulation (Note 5)
EN5 High, V
IN
= 5.5V, I
OUT
≤ 100mA
EN5 High, V
IN
= 12V, I
OUT
≤ 100mA
EN5 High, V
IN
= 38V, I
OUT
= 0mA
EN5 High
V
OUT5
Rising Makes PG5 Go Low
V
OUT5
Falling Makes PG5 Go Hi-Z
V
OUT5
Rising Makes PG5 go Hi-Z
V
OUT5
Falling Makes PG5 go Low
I
PG5
= 100µA
V
PG5
= 5V
EN3 High, V
IN
= 5.5V, I
OUT
≤ 250mA
EN3 High, V
IN
= 12V, I
OUT
≤ 250mA
EN3 High, V
IN
= 38V, I
OUT
= 0mA
V
OUT3
Rising Makes PG3 Go Low
V
OUT3
Falling Makes PG3 Go Hi-Z
V
OUT3
Rising Makes PG3 Go Hi-Z
V
OUT3
Falling Makes PG3 Go Low
I
PG3
= 100µA
V
PG3
= 5V
EN3 and/or EN5 High, I
REFOUT
= 0mA
l
l
l
l
elecTrical characTerisTics
CONDITIONS
l
l
MIN
5.5
TYP
1.8
0.5
15
20
1.2
MAX
38
2.7
2
30
35
2
1
3
UNITS
V
V
µA
µA
µA
V
V
µA
µA
V
mA
Ω
Ω
Shutdown
Output In Regulation, No Load
Output In Regulation, No Load
0.4
V
PIN
= 0V
V
PIN
= 38V
EN3 and/or EN5 High
V
OUTCP
= GND
2:1 Step-Down Mode
1:1 Step-Down Mode, V
IN
= 5.5V
4.85
4.85
4.85
–1
0.9
0
1
5.05
600
2
2
5.05
5.05
5.05
0.6
5.25
5.1
5.4
5.19
5.19
5.19
V
V
V
Ω
V
V
V
V
OUTCP to OUT5 Power Switch
On-Resistance
OUT5 Overvoltage Threshold
OUT5 Undervoltage Threshold
PG5 Output Low Voltage
PG5 Output Hi-Z Leakage
3.3V LDO Operation
V
OUT3
Fixed 3.3V LDO Output Regulation (Note 5)
l
l
l
4.6
–1
3.170
3.200
3.234
4.9
4.75
0.1
0
3.30
3.30
3.30
3.465
3.35
0.4
1
3.366
3.366
3.366
3.58
V
µA
V
V
V
V
V
V
V
l
l
l
l
OUT3 Overvoltage Threshold
OUT3 Undervoltage Threshold
PG3 Output Low Voltage
PG3 Output Hi-Z Leakage
Buffered 1.1V Reference Output (REFOUT)
REFOUT Pin Output Voltage
REFOUT Pin Output Resistance
Reset Timer Control (RT)
External Timer RT Pull-Up Current
External Timer RT Pull-Down Current
Internal Timer RT Pull Down Current
RT Internal Timer Select Threshold
l
l
l
3.04
–1
1.068
3.24
3.135
0.1
0
1.1
2
0.4
1
1.132
4
–2.6
2.6
1
2.7
V
µA
V
kΩ
µA
µA
µA
V
3256fb
l
V
RT
= 0.3V
V
RT
= 1.3V
V
RT
= V
OUTCP
l
l
l
l
–1.1
1.1
1.8
–1.9
1.9
0.25
2.3
For more information
www.linear.com/LTC3256
3
LTC3256
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 3). V
IN
= 12V, C
FLY
= 1µF unless otherwise noted.
SYMBOL
PARAMETER
RSTI Input High Voltage
RSTI Input Low Voltage
RSTI Input Low Current
RSTI Input High Current
Reset Output (RST)
t
RST(INT)
t
RST(EXT)
t
UV
Internal Reset Timeout Period
External Reset Timeout Period
RSTI Low to
RST
Asserted
RST
Output Voltage Low
RST
Output Voltage High Leakage
Watchdog Timer Control (WT)
External Timer WT Pull-Up Current
External Timer WT Pull-Down Current
Internal Timer WT Detect Pull Down Current
WT Internal Timer Select Threshold
Watchdog Input (WDI)
t
WDU(INT)
t
WDL(INT)
t
WDR(EXT)
t
WDU(EXT)
t
WDL(EXT)
Internal Watchdog Upper Boundary
Internal Watchdog Lower Boundary
External Watchdog Reset Time
External Watchdog Upper Boundary
External Watchdog Lower Boundary
WDI Input High Voltage
WDI Input Low Voltage
WDI Input Low Current
WDI Input High Current
Input Pulsewidth
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings may
cause permanent damage to the device. Exposure to any Absolute Maximum
Rating condition for extended periods may affect device reliability and lifetime.
Note 2:
All voltages are referenced to GND unless otherwise specified.
Note 3:
The LTC3256E is guaranteed to meet performance specifications
from 0°C to 85°C operating junction temperature. Specifications over
the –40°C to 125°C operating junction temperature range are assured by
design, characterization and correlation with statistical process controls.
The LTC3256I is guaranteed over the –40°C to 125°C operating junction
temperature range. The LTC3256H is guaranteed over the –40°C to 150°C
operating junction temperature range. The LTC3256MP is guaranteed and
tested over the –55°C to 150°C operating junction temperature range.
High junction temperatures degrade operating lifetimes; operating lifetime
is derated for junction temperatures greater than 125°C. Note that the
maximum ambient temperature consistent with these specifications is
determined by specific operating conditions in conjunction with board layout,
the rated package thermal resistance and other environmental factors.
V
WD_IN
= 0V
V
WD_IN
= 5V
l
elecTrical characTerisTics
Reset Timer Input (RSTI)
CONDITIONS
l
l
MIN
TYP
1.2
MAX
1.26
1
1
260
44
150
0.4
1
–2.6
2.6
1
2.7
2
62.5
340
UNITS
V
V
µA
µA
ms
ms
µs
V
µA
μA
μA
μA
V
s
ms
ms
ms
ms
V
V
µA
µA
ns
1.1
–1
–1
150
26
10
–1
–1.1
1.1
1.8
1.3
37.5
200
1.16
0
0
200
32
80
0.1
0
–1.9
1.9
0.25
2.3
1.6
50
260
V
RST_IN
= 0V
V
RST_IN
= 5V
V
RT
= V
OUTCP
C
RT
= 2.2nF
From RSTI falling to 1V or less
V
OUTCP
= 5V, I
RST
= 100µA
RST
= 5V
V
WT
= 0.3V
V
WT
= 1.3V
V
WT
= V
OUTCP
l
l
l
l
l
l
l
l
l
l
l
V
WT
= V
OUTCP
V
WT
= V
OUTCP
C
WT
= 2.2nF
l
l
l
t
WDR(EXT)
• (128/129)
t
WDR(EXT)
• (5/129)
1.2
0.4
–1
–1
100
0.9
0
0
1
1
2
The junction temperature (T
J
, in °C) is calculated from the ambient
temperature (T
A
, in °C) and power dissipation (P
D
, in Watts) according to
the formula:
T
J
= T
A
+ (P
D
•
θ
JA
)
where
θ
JA
(in °C/W) is the package thermal impedance.
Note 4:
This IC has overtemperature protection that is intended to protect
the device during momentary overload conditions. Junction temperatures
will exceed 150°C when overtemperature protection is active. Continuous
operation above the specified maximum operating junction temperature
may impair device reliability.
Note 5:
The maximum operating junction temperature of 150°C must be
followed. Certain combinations of input voltage and output current will
cause the junction temperature to exceed 150°C and must be avoided. See
Thermal Management section for information on calculating maximum
operating conditions. Due to thermal limitations of production equipment,
