LM5064 Datasheet, PDF (30/51 Pages) Texas Instruments – Negative Voltage System Power Management and Protection IC with PMBus

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. Writ-
ing 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 com-
mand 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 LM5064. This command is read with the PMBus read
byte protocol.
Value
B0h
TABLE 3. CAPABILITY Register
Meaning
Default
Supports Packet B0h
Error Check,
400Kbits/sec,
Supports SMBus
Alert
VOUT_UV_WARN_LIMIT (43h)
The VOUT_UV_WARN_LIMIT command is a standard PM-
Bus 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 the
Telemetry and Warning Conversion Coefficients Table. Ac-
cesses 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
threshold
0000h (disabled)
0000h
VOUT Under-
n/a
Voltage Warning
disabled
OT_FAULT_LIMIT (4Fh)
The OT_FAULT_LIMIT command is a standard PMBus com-
mand that allows configuring or reading the threshold for the
over-temperature fault detection. Reading and writing to this
register should use the coefficients shown in the Telemetry
and Warning Conversion Coefficients Table. Accesses to this
command should use the PMBus read or write word protocol.
If the measured temperature exceeds this value, an over-
temperature 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 regis-
ter, the MOSFET may be switched back on with the OPER-
ATION command. A single temperature measurement is an
average of 16 round-robin cycles; therefore, the minimum
temperature fault detection time is 16 ms.
TABLE 5. OT_FAULT_LIMIT Register
Value
Meaning
Default
0h – 0FFEh
Over-temperature 0960h (150°C)
Fault threshold
value
0FFFh
Over-temperature n/a
Fault detection
disabled
OT_WARN_LIMIT (51h)
The OT_WARN_LIMIT command is a standard PMBus com-
mand that allows configuring or reading the threshold for the
over-temperature warning detection. Reading and writing to
this register should use the coefficients shown in the Teleme-
try and Warning Conversion Coefficients Table. Accesses to
this command should use the PMBus read or write word pro-
tocol. If the measured temperature exceeds this value, an
over-temperature warning is triggered and the OT WARN
flags set in the respective registers and the SMBA signal as-
serted. A single temperature measurement is an average of
16 round-robin cycles; therefore, the minimum temperature
warn detection time is 16 ms.
TABLE 6. OT_WARN_LIMIT Register
Value
Meaning
Default
0h – 0FFEh
Over-Temperature 07D0h (125°C)
Warn Threshold
Value
0FFFh
Over-Temperature n/a
Warn detection
disabled
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