Texas Instruments Evaluation Module for TPS24711 Positive Voltage, Power-Limiting Hotswap Controller TPS24711EVM-004 TPS24711EVM-004 Datenbogen
Produktcode
TPS24711EVM-004
SLVSAL2E – JANUARY 2011 – REVISED NOVEMBER 2013
SYSTEM OPERATION
INTRODUCTION
The TPS24710/11/12/13 provides all the features needed for a positive hot-swap controller. These features
include:
•
include:
•
Undervoltage lockout
•
Adjustable (system-level) enable
•
turn-on inrush limiting
•
High-side gate drive for an external N-channel MOSFET
•
MOSFET protection by power limiting
•
Adjustable overload timeout — also called an electronic circuit breaker
•
Charge-complete indicator for downstream converter coordination
•
A choice of latch (TPS24710/12) or automatic restart mode (TPS24711/13)
The typical application diagram on the front page of this data sheet, and oscilloscope plots shown in
through
and
through
, demonstrate many of the functions described previously.
BOARD PLUG IN
and
illustrate the inrush current that flows when a hot swap board under the control of the
TPS24710/11/12/13 is plugged into a system bus. Only the bypass capacitor charge current and small bias
currents are evident when a board is first plugged in. The TPS24710/11/12/13 is held inactive, for a short period
while internal voltages stabilize. During this period GATE, PROG, TIMER are held low and PG, FLT, PGb, and
FLTb are held open drain. When the voltage on the internal VCC rail exceeds approximately 1.5 V, the power-on
reset (POR) circuit initializes the TPS24710/11/12/13 and a start-up cycle is ready to take place.
currents are evident when a board is first plugged in. The TPS24710/11/12/13 is held inactive, for a short period
while internal voltages stabilize. During this period GATE, PROG, TIMER are held low and PG, FLT, PGb, and
FLTb are held open drain. When the voltage on the internal VCC rail exceeds approximately 1.5 V, the power-on
reset (POR) circuit initializes the TPS24710/11/12/13 and a start-up cycle is ready to take place.
GATE, PROG, TIMER, PG, FLT, PGb, and FLTb are released after the internal voltages have stabilized and the
external EN (enable) thresholds have been exceeded. The part begins sourcing current from the GATE pin to
turn on MOSFET M
external EN (enable) thresholds have been exceeded. The part begins sourcing current from the GATE pin to
turn on MOSFET M
1
. The TPS24710/11/12/13 monitors both the drain-to-source voltage across MOSFET M
1
and the drain current passing through it. Based on these measurements, the TPS24710/11/12/13 limits the drain
current by controlling the gate voltage so that the power dissipation within the MOSFET does not exceed the
power limit programmed by the user. The current increases as the voltage across the MOSFET decreases until
finally the current reaches the current limit I
current by controlling the gate voltage so that the power dissipation within the MOSFET does not exceed the
power limit programmed by the user. The current increases as the voltage across the MOSFET decreases until
finally the current reaches the current limit I
LIM
.
14
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