LTC4417_15 Datasheet, PDF (1/32 Pages) Linear Technology – Prioritized PowerPat Controller

Features
n _{Selects Highest Priority Supply from Three Inputs}
n _{Blocks Reverse and Cross Conduction Currents}
n _{Wide Operating Voltage Range: 2.5V to 36V}
n _{–42V Protection Against Reverse Battery}
Connection
n _{Fast Switchover Minimizes Output Voltage Droop}
n _{Low 28µA Operating Current}
n _{<1µA Current Draw from Supplies Less than VOUT}
n _{1.5% Input Overvoltage/Undervoltage Protection}
n _{Adjustable Overvoltage/Undervoltage Hysteresis}
n _{P-Channel MOSFET Gate Protection Clamp}
n _{Cascadable for Additional Input Supplies}
n _{24-Lead Narrow SSOP and 4mm × 4mm QFN}
Packages
Applications
n _{Industrial Handheld Instruments}
n _{High Availability Systems}
n _{Battery Backup Systems}
n _{Servers and Computer Peripherals}
LTC4417
Prioritized PowerPath™
Controller
Description
The LTC^®4417 connects one of three valid power supplies
to a common output based on priority. Priority is defined
by pin assignment, with V1 assigned the highest priority
and V3 the lowest priority. A power supply is defined as
valid when its voltage has been within its overvoltage (OV)
and undervoltage (UV) window continuously for at least
256ms. If the highest priority valid input falls out of the
OV/UV window, the channel is immediately disconnected
and the next highest priority valid input is connected to the
common output. Two or more LTC4417s can be cascaded
to provide switchover between more than three inputs.
The LTC4417 incorporates fast non-overlap switching
circuitry to prevent both reverse and cross conduction
while minimizing output droop. The gate driver includes
a 6V clamp to protect external MOSFETs. A controlled
output ramp feature minimizes start-up inrush current.
Open drain VALID outputs indicate the input supplies have
been within their OV/UV window for 256ms.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PowerPath, ThinSOT and Hot Swap are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
Typical Application
V1: 12V
WALL ADAPTER
IRF7324
V2: 14.8V Li-Ion
MAIN/SWAPPABLE
IRF7324
V3: 12V SLA
BACKUP
IRF7324
2A
OUTPUT
806k
39.2k
60.4k
V1 VS1 G1
UV1
OV1
V2
1.05M
UV2
31.6k
OV2
68.1k
V3
698k
UV3
16.9k
OV3
49.9k
VS2 G2
LTC4417
GND
VS3 G3
V_OUT
VALID1
VALID2
VALID3
1M 1M 1M
EN
SHDN
HYS
CAS
4417 TA01a
Priority Switching from 12V V1 to 14.8V V2
V2 ^14.8V
12V
V1
2V/DIV
V3 = 0V, I_L = 2A
C_L = 120µF
V_OUT
V1 UV FAULT
50ms/DIV
4417 TA01b
4417f
1