LTC4417_15 Datasheet, PDF (11/32 Pages) Linear Technology – Prioritized PowerPat Controller

LTC4417
Applications Information
Introduction
The LTC4417 is an intelligent high voltage triple load switch
which automatically connects one of three input supplies
to a common output based on predefined pin priorities
and validity. V1 is defined to be the highest priority and
V3 the lowest priority, regardless of voltage. An input
supply is defined valid when the voltage remains in the
user defined overvoltage (OV) and undervoltage (UV)
window for at least 256ms.
If a connected input supply falls out of the user defined
OV/UV window and remains outside the OV/UV window
for at least 8µs, the channel is disconnected and the next
highest valid priority is connected to the common output.
If a lower priority input supply is connected to V_OUT and a
higher priority input supply becomes valid, the LTC4417
disconnects the lower priority supply and connects the
higher priority input supply to V_OUT.
Typical LTC4417 applications are systems where predict-
able autonomous load control of multiple input supplies is
desired. These supplies may not necessarily be different
in voltage, nor must the highest voltage be the primary
supply. A typical LTC4417 application circuit is shown in
Figure 1. External component selection is discussed in
detail in the following sections.
12V WALL
ADAPTER
+
7.4V Li-Ion
PRIMARY
BATTERY
+
C_IN1
2200µF
IRF7324
M1
M2
IRF7324
M3
M4
V_OUT
+ _CL
100µF
7.4V Li-Ion
SECONDARY
BATTERY
+
C_V3
0.1µF
C_V2
0.1µF
R9
931k
R8
63.4k
R7
137k
C_V1
0.1µF
R6
931k
R5
63.4k
R4
137k
C_VS1
0.1µF
C_VS2
0.1µF
VS1 G1
V1
R3
806k
UV1
R2
39.2k
OV1
R1
60.4k
V2
UV2
IRF7324
M5
M6
LTC3690
SWITCHING
REGULATOR
C_VS3
0.1µF
VS2 G2
VS3 G3
V_OUT
3.3V
4A
R10 R11 R12
1M 1M 1M
VALID1
VALID2
VALID3
ADAPTER
INVALID
PRIMARY INVALID
SECONDARY INVALID
LTC4417
OV2
V3
EN
SHDN
UV3
HYS
CAS
OV3
GND
4417 F01
Figure 1. Typical Hand Held Computer Application.
4417f
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