Datasheet

LM5066

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SNVS655G –JUNE 2011–REVISED FEBRUARY 2013

STANDARD PMBUS COMMANDS

OPERATION (01h)

The OPERATION command is a standard PMBus command that controls the MOSFET switch. This command

may be used to switch the MOSFET ON and OFF under host control. It is also used to re-enable the MOSFET

after a fault triggered shutdown. Writing an OFF command, followed by an ON command, will clear all faults and

re-enable the device. Writing only an ON after a fault-triggered shutdown will not clear the fault registers or re-

enable the device. The OPERATION command is issued with the write byte protocol.

Table 2. Recognized OPERATION Command Values

Value Meaning Default

80h Switch ON 80h

00h Switch OFF n/a

CLEAR FAULTS (03h)

The CLEAR_FAULTS command is a standard PMBus command that resets all stored warning and fault flags

and the SMBA signal. If a fault or warning condition still exists when the CLEAR_FAULTS command is issued,

the SMBA signal may not clear or will re-assert almost immediately. Issuing a CLEAR_FAULTS command will

not cause the MOSFET to switch back on in the event of a fault turnoff - that must be done by issuing an

OPERATION command after the fault condition is cleared. This command uses the PMBus send byte protocol.

CAPABILITY (19h)

The CAPABILITY command is a standard PMBus command that returns information about the PMBus functions

supported by the LM5066. This command is read with the PMBus read byte protocol.

Table 3. CAPABILITY Register

Value Meaning Default

B0h Supports Packet Error Check, 400Kbits/sec, B0h

Supports SMBus Alert

VOUT_UV_WARN_LIMIT (58h)

The VOUT_UV_WARN_LIMIT command is a standard PMBus command that allows configuring or reading the

threshold for the VOUT Under-voltage Warning detection. Reading and writing to this register should use the

coefficients shown in Table 41. Accesses to this command should use the PMBus read or write word protocol. If

the measured value of VOUT falls below the value in this register, VOUT UV Warn flags are set and the SMBA

signal is asserted.

Table 4. VOUT_UV_WARN_LIMIT Register

Value Meaning Default

1h – 0FFFh VOUT Under-voltage Warning detection 0000h (disabled)

threshold

0000h VOUT Under-voltage Warning disabled n/a

OT_FAULT_LIMIT (4Fh)

The OT_FAULT_LIMIT command is a standard PMBus command that allows configuring or reading the threshold

for the overtemperature fault detection. Reading and writing to this register should use the coefficients shown in

Table 41. Accesses to this command should use the PMBus read or write word protocol. If the measured

temperature exceeds this value, an overtemperature fault is triggered and the MOSFET is switched off, OT

FAULT flags set, and the SMBA signal asserted. After the measured temperature falls below the value in this

measurement is an average of 16 round-robin cycles; therefore, the minimum temperature fault detection time is

16 ms.

Product Folder Links: LM5066