lm5066pmhx National Semiconductor Corporation, lm5066pmhx Datasheet - Page 35

• Manufacturer Part Number: lm5066pmhx
• Description: High Voltage System Power Management And Protection Ic With Pmbus
• Manufacturer: National Semiconductor Corporation

MFR_SPECIFIC_09: DEVICE_SETUP (D9h)
The DEVICE_SETUP command may be used to override pin
settings to define operation of the LM5066 under host control.
This command is accessed with the PMBus read / write byte
protocol.
In order to configure the Current Limit Setting via this register,
it is necessary to set the Current Limit Configuration bit (2) to
1 to enable the register to control the current limit function and
the Current Limit Setting bit (4) to select the desired setting.
If the Current Limit Configuration bit is not set, the pin setting
will be used. The Circuit Breaker to Current Limit ratio value
is set by the CB / CL Ratio bit (3). Note that if the Current Limit
Configuration is changed, the samples for the telemetry av-
eraging function will not be reset. It is recommeded to allow
a full averaging update period with the new Current Limit
Configuration before processing the averaged data.
Note that the Current Limit Configuration affects the coeffi-
cients used for the Current and Power measurements and
warning registers.
MFR_SPECIFIC_10: BLOCK_READ (DAh)
The
DIAGNOSTIC_WORD with input and output telemetry infor-
mation (IIN, VOUT, VIN, PIN) as well as TEMPERATURE to
capture all of the operating information of the LM5066 in a
single SMBus transaction. The block is 12 bytes long with
telemetry information being sent out in the same manner as
if an individual READ_XXX command had been issued
(shown below). The contents of the block read register are
updated every clock cycle (85ns) as long as the SMBus in-
7:5
Bit
4
3
2
1
0
BLOCK_READ
TABLE 30. DEVICE_SETUP Byte Format
Current limit setting
Configuration
Retry setting
Current Limit
CB/CL Ratio
Unused
Unused
Name
BIT
5
4
3
2
1
0
command
000 = Pin configured retries
1 = Use SMBus settings
0 = High setting (50mV)
1 = Low setting (26mV)
111 = Unlimited retries
1 = High setting (3.9x)
0 = Low setting (1.9x)
110 = Retry 16 times
0 = Use pin settings
101 = Retry 8 times
100 = Retry 4 times
011 = Retry 2 times
010 = Retry 1 time
001 = No retries
concatenates
Meaning
CML FAULT (Communications Fault)
OVERTEMPERATURE FAULT
VIN UNDERVOLTAGE FAULT
VIN OVERVOLTAGE FAULT
CIRCUIT BREAKER FAULT
IIN/PFET FAULT
the
NAME
35
terface is idle. BLOCK_READ also guarantees that the VIN,
VOUT, IIN and PIN measurements are all time-aligned. If
separate commands are used, individual samples may not be
time-aligned, because of the delay necessary for the com-
munication protocol.
The Block Read command is read via the PMBus block read
protocol.
MFR_SPECIFIC_11: SAMPLES_FOR_AVG (DBh)
The SAMPLES_FOR_AVG command is a manufacturer spe-
cific command for setting the number of samples used in
computing the average values for IIN, VIN, VOUT, PIN. The
decimal equivalent of the AVGN nibble is the power of 2 sam-
ples, (e.g. AVGN=12 equates to N=4096 samples used in
computing the average). The LM5066 supports average num-
bers of 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096.
The SAMPLES_FOR_AVG number applies to average val-
ues of IIN, VIN, VOUT, PIN simultaneously. The LM5066 uses
simple averaging. This is accomplished by summing consec-
utive results up to the number programmed, then dividing by
the number of samples. Averaging is calculated according to
the following sequence:
When the averaging has reached the end of a sequence (for
example, 4096 samples are averaged), then a whole new se-
quence begins that will require the same number of samples
(in this example, 4096) to be taken before the new average is
ready.
Byte Count (always 12)
DIAGNOSTIC_WORD
VOUT_BLOCK
TEMP_BLOCK
AVGN
0000
0001
0010
0011
0100
0101
0110
0111
1000
VIN_BLOCK
PIN_BLOCK
IIN_BLOCK
TABLE 31. BLOCK_READ Register Format
TABLE 32. SAMPLES_FOR_AVG Register
Y = (X
(N)
N = 2
+ X
128
256
16
32
64
1
2
4
8
(N-1)
AVGN
+ ... + X
DEFAULT
1
0
0
0
0
0
Averaging/Register
Update Period (ms)
(1 Word)
(1 Word)
(1 Word)
(1 Word)
(1 Word)
(1 Word)
(1 byte)
(0)
) / N
128
256
16
32
64
1
2
4
8
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