Rainbow Electronics MAX16064 - Manual (Page 33)

MAX16064
±0.3% Accurate, Quad, Power-Supply Controller with
Active-Voltage Output Control and PMBus Interface
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Table 4. MAX16064 PMBus Command Summary (continued)
(Global commands are shaded; they are not dependent on the PAGE)
PAGE COMMAND
CODE
COMMAND NAME
TRANSACTION
TYPE 0-3 255
NO. OF
BYTES
m b R
MANUFACTURER-SPECIFIC COMMANDS
D0h MFR_SMB_LOOPBACK R/W Word R/W 2 — — —
D1h MFR_MODE R/W Word R/W 2 — — —
D3h MFR_SAMPLE_RATE R/W Word R/W 2 — — —
D4h MFR_VOUT_PEAK Read Word R/W R/W 2 19995 0 -1
D6h MFR_TEMPERATURE_PEAK Read Word R/W 2 7612 335 -3
D8h MFR_STATUS_WORD R/W Word R R 2 — — —
D9h MFR_FAULT_RESPONSE R/W Word R/W W 2 — — —
DAh MFR_FAULT_RETRY R/W Word R/W W 2 — — —
DBh MFR_SET_ADDRESS R/W Byte R/W 1 — — —
DDh MFR_RESET_DELAY R/W Word R/W 2 1 0 1
DEh MFR_MODE_OUTPUT R/W Word R/W W 2 — — —
DFh MFR_VLTO R/W Byte R/W 1 — — —
E0h MFR_DAC_ACT_CNT R/W Byte R/W 1 — — —
E1h MFR_RESET_OUTPUT R/W Byte R/W 1 — — —
E2h MFR_FAULT_REASON R/W Word R/W 2 — — —
E3h MFR_FAULT_VOUT R/W Word R/W W 2 — — —
E4h MFR_FAULT_TEMP R/W Word R/W 2 — — —
The following example demonstrates how the host can
send and retrieve values from the MAX16064.
From Table 4, the coefficients used in the following
parameters are:
VOUT_COMMAND: m = 19995, b = 0, R = -1
READ_VOUT: m = 19995, b = 0, R = -1
If a host wants to command the power supply to output a
voltage of 3.0V, the corresponding VOUT_COMMAND
value is:
Y = (mX + b) x 10 R
Y = (19995 x 3.0 + 0) x 10 -1 = 5998.5
(decimal) = 176Eh (hex)
Conversely, if the host received a value of 176Eh on a
READ_VOUT command, this is equivalent to:
Power supplies and power converters generally have
no way of knowing how their outputs are connected to
ground. Within the power supply, all output voltages are
most commonly treated as positive. Accordingly, all
output voltages and output voltage-related parameters
of PMBus devices are commanded and reported as
positive values. It is up to the system to know that a
particular output is negative if that is of interest to the
system.
All output voltage-related commands use 2 data bytes.
Fault Management and Reporting
For reporting faults/warnings to the host on a real-time
basis, the MAX16064 asserts the open-drain
SMBALERT pin and sets the appropriate bit in the
STATUS_BYTE and MFR_FAULT_STATUS registers,
respectively. On recognition of the SMBALERT asser-
tion, the host or system manager is expected to poll the
I
2 C bus to determine the device asserting SMBALERT.
The host sends the SMBus Alert Response Address
(0001100). The MAX16064 will ACK the SMBus Alert
Response Address, transmit its slave address, and
deassert SMBALERT. The system controller then
X Eh = × −
( )
= =
− −
1
19995
176 10 0 59980 19995 2 9
1 ( )
. 9 99750
0 0083 3 0 . % . . which is within of V
X
m
Y b
R
= Ч −
( ) −
1
10