LTC2922_15 Datasheet, PDF (1/20 Pages) Linear Technology – Power Supply Tracker with Input Monitors

LTC2921/LTC2922 Series
Power Supply Tracker
with Input Monitors
FEATURES
DESCRIPTIO
s _{Tracks Multiple Supplies with MOSFET Switches}
s _{Monitors 5 Input Voltages Including VCC}
s _{Guaranteed Threshold Accuracy: ±1% at 0.5V}
s _{Automatic Remote Sense Switching}
s _{Adjustable Supply Ramp Rate}
s _{Overvoltage Monitor}
s _{Adjustable Electronic Circuit Breaker}
s _{Adjustable Power-Good Delay}
s _{Available for VCC Supply Voltages of 5V, 3.3V and 2.5V}
s _{Available in 16-Pin Narrow SSOP (LTC2921 Series)}
and 20-Pin TSSOP (LTC2922 Series)
U
APPLICATIO S
s _{Desktop Computers}
s _{Plug-In Cards}
s _{Telecom Infrastructure}
s _{Supply Sequencing}
s _Instruments
The LTC^®2921 and LTC2922 monitor up to five supplies
and force them to track on power-up in multiple supply
systems. Using external N-channel pass transistors, the
supplies can be ramped up at an adjustable rate. Auto-
matic remote sense switching allows the DC/DC convert-
ers to compensate for series voltage drops in the wiring.
An incorrect level on one or more of the supplies triggers
disconnect of all supplies. Tight 1% accuracy and glitch
immunity on the low 0.5V monitoring level ensure no false
error disconnects.
The LTC2921 and LTC2922 each feature an adjustable
electronic circuit breaker to protect the V_CC supply against
short circuits. Capacitance at the TIMER pin programs the
delays in the monitoring sequence.
The LTC2921 includes three remote sense switches in a
16-pin narrow SSOP package, while the LTC2922 includes
five remote sense switches in a 20-pin TSSOP package.
Both parts are available for V_CC supply voltages of 5V,
3.3V, and 2.5V.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
Three-Supply Tracker and Monitor (5V, 3.3V, 2.5V)
V_OUT ^{5V SUPPLY}
V_FB
DC/DC
CONVERTER
100Ω
WSL1206
0.05Ω
Si2316DS
10Ω
5V
LOAD
V_OUT ^{3.3V SUPPLY}
V_FB
DC/DC
CONVERTER
100Ω
Si2316DS
10Ω
3.3V
LOAD
V_OUT ^{2.5V SUPPLY}
V_FB
100Ω
DC/DC
CONVERTER
Si1012R
CBRST
100k
CIRCUIT BREAKER
RESET CONTROL
243k 169k
49.9k 49.9k
Si2316DS
10Ω
V_CC SENSE
V1
GATE
V2
V3 LTC2921
V4
PG
S1
S2
S3
GND
D1
D2
D3
TIMER
0.47µF
0.22µF
2.5V
LOAD
4.7k
RESET
t_GATE ~ 500ms
t_TIMER ~ 130ms
2921/22 TA01
Load Voltage Ramp-Up and
Power-Good Activation
2.5V SUPPLY
2V/DIV
OUTPUTS
2V/DIV
5V LOAD
3.3V LOAD
2.5V LOAD
PG
2V/DIV
5V SUPPLY AT 5V 100ms/DIV
3.3V SUPPLY AT 3.3V
2921/22 TA01b
29212fa
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