LM5066 datasheet(13/63 Pages) TI

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OUT

UVLO/EN

VIN

GATE

DIODE

OVLO

SDAI

SCL

PGD

SENSE

VDD

SMBus

Interface

SMBA

RETRY

VAUX

VDD

VREF

TIMER

PWR

AGND

LM5066

Auxillary ADC Input

(0V ± 2.97V)

VOUT

COUT

RPG

VIN

1 PF

RPWR

ADR2

ADR1

ADR0

VDD

N/C

VIN_K

GND

SDAO

CTIMER

CIN

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, Q1.

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 (Q1) 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 VIN voltage reaches the POR threshold the insertion time begins. During the

insertion time, the capacitor at the TIMER pin (CT) is charged by a 4.8 µA current source, and Q1 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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