Datasheet

OUT
UVLO/EN
VIN
GATE
DIODE
R
1
FB
OVLO
SDAI
SCL
PGD
SENSE
VDD
SMBus
Interface
SMBA
CL
RETRY
VAUX
VDD
VREF
TIMER
PWR
AGND
LM5066
Auxillary ADC Input
(0V ± 2.97V)
V
OUT
C
OUT
R
PG
V
IN
1 PF
1 PF
R
PWR
ADR2
ADR1
ADR0
VDD
N/C
N/C
VIN_K
GND
SDAO
R
S
R
2
R
3
C
TIMER
R
4
R
5
C
IN
Z
1
D
1
Q
2
Q
1
LM5066
www.ti.com SNVS655G –JUNE 2011–REVISED FEBRUARY 2013
FUNCTIONAL DESCRIPTION
The inline protection functionality of the LM5066 is designed to control the in-rush current to the load upon
insertion of a circuit card into a live backplane or other “hot” power source, thereby limiting the voltage sag on the
backplane’s supply voltage, and the dV/dt of the voltage applied to the load. The effects on other circuits in the
system are minimized by preventing possible unintended resets. A controlled shutdown when the circuit card is
removed can also be implemented using the LM5066.
In addition to a programmable current limit, the LM5066 monitors and limits the maximum power dissipation in
the series pass device to maintain operation within the device Safe Operating Area (SOA). Either current limiting
or power limiting for an extended period of time results in the shutdown of the series pass device. In this event,
the LM5066 can latch off or repetitively retry based on the hardware setting of the RETRY pin. Once started, the
number of retries can be set to none, 1, 2, 4, 8, 16, or infinite. The circuit breaker function quickly switches off the
series pass device upon detection of a severe over-current condition. Programmable under-voltage lockout
(UVLO) and over-voltage lockout (OVLO) circuits shut down the LM5066 when the system input voltage is
outside the desired operating range.
The telemetry capability of the LM5066 provides intelligent monitoring of the input voltage, output voltage, input
current, input power, temperature, and an auxiliary input. The LM5066 also provides a peak capture of the input
power and programmable hardware averaging of the input voltage, current, power, and output voltage. Warning
thresholds which trigger the SMBA pin may be programmed for input and output voltage, current, power and
temperature via the PMBus interface. Additionally, the LM5066 is capable of detecting damage to the external
MOSFET, Q
1
.
Figure 1. Typical Application Circuit
Power Up Sequence
The VIN operating range of the LM5066 is 10V to 80V, with a transient capability to 100V. Referring to Figure 1
and Figure 2, as the voltage at VIN initially increases, the external N-channel MOSFET (Q
1
) is held off by an
internal 115 mA pull-down current at the GATE pin. The strong pull-down current at the GATE pin prevents an
inadvertent turn-on as the MOSFET’s gate-to-drain (Miller) capacitance is charged. Additionally, the TIMER pin is
initially held at ground. When the V
IN
voltage reaches the POR threshold the insertion time begins. During the
insertion time, the capacitor at the TIMER pin (C
T
) is charged by a 4.8 µA current source, and Q
1
is held off by a
4.2 mA pull-down current at the GATE pin regardless of the input voltage. The insertion time delay allows ringing
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