Maxim Integrated MAX15301 User Manual
MAX15301 PMBus Command Set
User’s Guide
Rev 1; 10/14
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MAX15301 PMBus Command Set User’s Guide
Reference:
<”Standard” or “Maxim Specific”>
Lockable:
<yes/no>
Command Code:
<hex value>
Format:
<data format>
Data Bytes:
<byte count>
Units:
<unit of measure>
Transfer:
<SMBus transaction>
Factory Value:
<Maxim setting>
Description/Notes:
<Command definition if Maxim-specific, or notes on command functionality where it differs from the
Introduction
Maxim Integrated InTune™ digital power products utilize the PMBus™ command standard for configuration, control and
telemetry.
This document lists and describes the PMBus commands implemented in the MAX15301 digital DC-DC controller. Standard
commands from the PMBus specification are not described in detail unless there are deviations from the PMBus
specification functionality. Maxim manufacturer-specific commands are fully described in this document.
References for this document are found on the PMBus and SMBus organization websites.
http://pmbus.org/specs.html
http://smbus.org/specs/
The commands in this document are presented in the following format:
<COMMAND_NAME>
PMBus specification.>
Part Number Differences
The MAX15301 controller is available under different part numbers with some functional differences as follows.
MAX15301AA01
The MAX15301AA01 has the first production firmware, version 4018.
MAX15301AA02
The MA15301AA02 has improved firmware, version 4328, with the following improvements:
• Changed to 2-point thermal measurement algorithm to improve the READ_TEMPERATURE_2 accuracy
• Added support for v6 final test/trim scheme (improves READ_TEMPERATURE_1 accuracy)
• Changed IC_DEVICE_ID length from 8 to 12 bytes
• PMBUS_REVISION changed to 0x22
• Changed EXT_TEMP_CAL defaults to improve READ_TEMPERATURE_2 accuracy
• Added SMBus timeout support
• Bug fix for interrupted PMBus read operations
• Bug fix for operation with FREQUENCY_SWITCH <400kHz and temperature sense diode connected to TEMPX
Rev 1 Page 2 of 53
MAX15301 PMBus Command Set User’s Guide
Table of Contents
Introduction ................................................................................................................................................................................. 1
Part Number Differences ............................................................................................................................................................. 2
MAX15301AA01 ....................................................................................................................................................................... 2
MAX15301AA02 ....................................................................................................................................................................... 2
On, Off, and Margin Testing Related Commands ........................................................................................................................ 7
OPERATION .............................................................................................................................................................................. 7
ON_OFF_CONFIG ..................................................................................................................................................................... 7
VIN_ON .................................................................................................................................................................................... 8
VIN_OFF ................................................................................................................................................................................... 9
Output Voltage Related Commands .......................................................................................................................................... 10
VOUT_MODE ......................................................................................................................................................................... 10
VOUT_COMMAND ................................................................................................................................................................. 10
VOUT_TRIM ........................................................................................................................................................................... 10
VOUT_CAL_OFFSET ................................................................................................................................................................ 11
VOUT_MAX ............................................................................................................................................................................ 11
VOUT_MARGIN_HIGH ........................................................................................................................................................... 11
VOUT_MARGIN_LOW ............................................................................................................................................................ 12
VOUT_TRANSITION_RATE ...................................................................................................................................................... 13
VOUT_DROOP ........................................................................................................................................................................ 13
Switching Frequency and PWM Commands .............................................................................................................................. 15
FREQUENCY_SWITCH ............................................................................................................................................................. 15
INTERLEAVE ........................................................................................................................................................................... 15
Output Voltage Sequencing Commands .................................................................................................................................... 16
POWER_GOOD_ON ............................................................................................................................................................... 16
POWER_GOOD_OFF .............................................................................................................................................................. 17
TON_DELAY ............................................................................................................................................................................ 17
TON_RISE ............................................................................................................................................................................... 18
TOFF_DELAY ........................................................................................................................................................................... 18
TOFF_FALL.............................................................................................................................................................................. 19
Fault Related Commands ........................................................................................................................................................... 20
CLEAR_FAULTS ....................................................................................................................................................................... 20
VOUT_OV_FAULT_LIMIT ........................................................................................................................................................ 20
VOUT_OV_FAULT_RESPONSE ................................................................................................................................................ 21
Rev 1 Page 3 of 53
MAX15301 PMBus Command Set User’s Guide
VOUT_UV_FAULT_LIMIT ........................................................................................................................................................ 21
VOUT_UV_FAULT_RESPONSE ................................................................................................................................................ 22
IOUT_OC_FAULT_LIMIT ......................................................................................................................................................... 22
IOUT_OC_FAULT_RESPONSE ................................................................................................................................................. 23
OT_FAULT_LIMIT ................................................................................................................................................................... 23
OT_FAULT_RESPONSE ........................................................................................................................................................... 24
OT_WARN_LIMIT ................................................................................................................................................................... 25
VIN_OV_FAULT_LIMIT ........................................................................................................................................................... 25
VIN_OV_FAULT_RESPONSE ................................................................................................................................................... 25
VIN_UV_FAULT_LIMIT ........................................................................................................................................................... 26
VIN_UV_FAULT_RESPONSE ................................................................................................................................................... 26
Unit Status Commands .............................................................................................................................................................. 28
STATUS_BYTE ......................................................................................................................................................................... 28
STATUS_WORD ...................................................................................................................................................................... 28
STATUS_VOUT ....................................................................................................................................................................... 28
STATUS_IOUT ......................................................................................................................................................................... 28
STATUS_INPUT ....................................................................................................................................................................... 29
STATUS_TEMPERATURE......................................................................................................................................................... 29
STATUS_CML .......................................................................................................................................................................... 29
Telemetry Commands ................................................................................................................................................................ 30
READ_VIN............................................................................................................................................................................... 30
READ_VOUT ........................................................................................................................................................................... 30
READ_IOUT ............................................................................................................................................................................ 30
READ_TEMPERATURE_1 ........................................................................................................................................................ 31
READ_TEMPERATURE_2 ........................................................................................................................................................ 31
READ_DUTY_CYCLE ................................................................................................................................................................ 31
READ_FREQUENCY ................................................................................................................................................................. 32
PMB_VALUES ......................................................................................................................................................................... 32
Calibration Commands .............................................................................................................................................................. 34
IOUT_CAL_GAIN ..................................................................................................................................................................... 34
IOUT_CAL_OFFSET ................................................................................................................................................................. 34
EXT_TEMP_CAL (MAX15301AA01) ........................................................................................................................................ 34
EXT_TEMP_CAL (MAX15301AA02) ........................................................................................................................................ 35
Device Identification Commands ............................................................................................................................................... 36
Rev 1 Page 4 of 53
MAX15301 PMBus Command Set User’s Guide
CAPABILITY ............................................................................................................................................................................. 36
PMBUS_REVISION .................................................................................................................................................................. 36
MFR_ID .................................................................................................................................................................................. 36
MFR_MODEL .......................................................................................................................................................................... 37
MFR_REVISION ...................................................................................................................................................................... 37
MFR_LOCATION ..................................................................................................................................................................... 37
MFR_DATE ............................................................................................................................................................................. 37
MFR_SERIAL ........................................................................................................................................................................... 38
IC_DEVICE_ID (MAX15301AA01) ........................................................................................................................................... 38
IC_DEVICE_ID (MAX15301AA02) ........................................................................................................................................... 38
IC_DEVICE_REV ...................................................................................................................................................................... 38
Security Commands ................................................................................................................................................................... 39
WRITE_PROTECT .................................................................................................................................................................... 39
MANUF_CONF ....................................................................................................................................................................... 39
MANUF_LOCK ........................................................................................................................................................................ 40
MANUF_PASSWD ................................................................................................................................................................... 40
USER_CONF ............................................................................................................................................................................ 40
USER_LOCK ............................................................................................................................................................................ 41
USER_PASSWD ....................................................................................................................................................................... 41
SECURITY_LEVEL .................................................................................................................................................................... 42
Memory and Storage Commands .............................................................................................................................................. 43
STORE_DEFAULT_ALL ............................................................................................................................................................ 43
RESTORE_DEFAULT_ALL ........................................................................................................................................................ 44
STORE_USER_ALL ................................................................................................................................................................... 44
RESTORE_USER_ALL............................................................................................................................................................... 46
RESTORE_MAXIM_ALL ........................................................................................................................................................... 46
STRAP_DISABLE ...................................................................................................................................................................... 47
Control Loop Commands ........................................................................................................................................................... 48
ADAPTIVE_MODE ................................................................................................................................................................... 48
FEEDBACK_EFFORT ................................................................................................................................................................ 49
LOOP_CONFIG ........................................................................................................................................................................ 49
COMP_MODEL ....................................................................................................................................................................... 50
DEADTIME_GCTRL ................................................................................................................................................................. 50
ZETA_P ................................................................................................................................................................................... 52
Rev 1 Page 5 of 53
MAX15301 PMBus Command Set User’s Guide
Trademarks ................................................................................................................................................................................ 53
Revision History ......................................................................................................................................................................... 53
Rev 1 Page 6 of 53
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x01
Format:
Bit field
Data Bytes:
1
Units:
N/A
Transfer:
Read/Write Byte
Factory Value:
0x40 (see Description table)
Description/Notes:
See Section 12.1 of the PMBus Specification Part II.
On, Off, and Margin Testing Related Commands
OPERATION
If the values of VOUT_OV_FAULT_LIMIT or VOUT_UV_FAULT_LIMIT are set between the values of
VOUT_MARGIN_HIGH and VOUT_MARGIN_LOW, it is possible that a fault will be detected when
exiting the “Margin High/Low (Ignore Fault)” command states. This occurs when fault detection is reenabled before the output has had time to return to the
be avoided in most cases by increasing the value of VOUT_TRANSITION_RATE, thereby decreasing the
amount of time required for the output to return to normal VOUT_COMMAND setpoint.
The value of the OPERATION command is maintained in volatile memory, and cannot be stored in the
Default Store or User Store nonvolatile memory. This prevents inadvertent preservation of a
margin-high or margin-low state. If it is desired to keep the output always enabled or always disabled
upon power-up, this can be achieved by storing the appropriate value of the ON_OFF_CONFIG
command.
MAX15301 PMBus Command Set User’s Guide
VOUT_COMMAND value. This condition can
Useful values for the OPERATION command:
0x00 Immediate-off, no sequencing: both DH and DL outputs low
0x40 Soft-off, with sequencing (factory setting)
0x80 Output enabled, if allowed by ON_OFF_CONFIG setting (note: same as 0x81-0x8F)
0x94 Margin low, ignore faults (note: same as 0x95-0x97)
0x98 Margin low, act on faults (note: same as 0x99-0x9B)
0xA4 Margin high, ignore faults (note: same as 0xA5-0xA7)
0xA8 Margin high, act on faults (note: same as 0xA9-0xAB)
Invalid values for the OPERATION command:
0x90-0x93
0x9C-0x9F
0xA0-0xA3
0xAC-0xFF
These invalid data bytes will trigger an “Invalid Or Unsupported Data” response per section 10.9.3 of
the PMBus specification.
After writing the OPERATION command to enable the output, the PMBus master must either wait for
a time equal to (TON_DELAY + TON_RISE + 50ms), or wait for PG to assert, before sending additional
PMBus commands.
ON_OFF_CONFIG
a
An “immediate-off,” “hard-stop,” or “tri-state” shutdown means the MAX15301 will stop switching and keep both DH and
DL outputs low, allowing the output voltage to decay naturally according to load and output capacitance.
b
In this application note (and other InTune documents) a “soft-off,” “soft-stop,” or “ramp-down” shutdown means the
MAX15301 actively controls the output voltage along a linear ramp to zero Volts, per the TOFF_DELAY and TOFF_FALL
values.
a
b
(note: same as 0x41-0x7F)
(note: same as 0x01-0x3F)
Rev 1 Page 7 of 53
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x02
Format:
Bit field
Data Bytes:
1
Units:
N/A
Transfer:
Read/Write Byte
Factory Value:
0x16 (see Description table)
Description/Notes:
See Section 12.2 of the PMBus Specification Part II.
writing the ON_OFF_CONFIG command to enable the output, the PMBus master must either
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x35
Format:
Linear
Data Bytes:
2
Units:
V
Transfer:
Read/Write Word
Factory Value:
0xCB00 (6.0V)
Description/Notes:
See Section 14.5 of the PMBus Specification Part II.
ON_OFF_CONFIG
MAX15301 PMBus Command Set User’s Guide
Useful Values for the ON_OFF_CONFIG command:
0x00 Output always enabled (note: same as 0x01-0x0F)
0x10 Output always disabled (note: same as 0x11-0x13)
0x14 Ignore bit 7 of OPERATION
0x15 Ignore bit 7 of OPERATION, require EN low to run, immediate-off on loss of EN
0x16 Ignore bit 7 of OPERATION, require EN high to run, soft-off on loss of EN (factory setting)
0x17 Ignore bit 7 of OPERATION, require EN high to run, immediate-off on loss of EN
0x18 Require bit 7 of OPERATION to run, ignore EN (note: same as 0x19-0x1B)
0x1C Require bit 7 of OPERATION and EN low to run, soft-off on loss of EN
0x1D Require bit 7 of OPERATION and EN low to run, immediate-off on loss of EN
0x1E Require bit 7 of OPERATION and EN high to run, soft-off on loss of EN
0x1F Require bit 7 of OPERATION and EN high to run, immediate-off on loss of EN
, require EN low to run, soft-off on loss of EN
In general, odd values of ON_OFF_CONFIG that require a valid EN signal will have an immediate-off
shutdown when EN is not valid. Even values that require EN will have a soft-off shutdown when EN is
not valid.
After
wait for a time equal to (TON_DELAY + TON_RISE + 50ms), or wait for PG to assert, before sending
additional PMBus commands.
VIN_ON
The MAX15301 hardware has 8-bit resolution for the minimum input voltage required for regulation,
to a maximum value of ≈14.75V.
The desired value of VIN_ON is retained in memory, regardless limitations imposed by the 8-bit fault
limit resolution, but the read-back value is based on actual hardware register settings.
Rev 1 Page 8 of 53
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x36
Format:
Linear
Data Bytes:
2
Units:
V
Transfer:
Read/Write Word
Factory Value:
0xCAC0 (5.5V)
Description/Notes:
See Section 14.6 of the PMBus Specification Part II.
VIN_OFF
The MAX15301 hardware has 8-bit resolution for the minimum input voltage required for regulation,
to a maximum value of ≈14.75V.
The desired value of VIN_OFF is retained in memory, regardless limitations imposed by the 8-bit fault
limit resolution, but the read-back value is based on actual hardware register settings.
MAX15301 PMBus Command Set User’s Guide
Rev 1 Page 9 of 53
Reference:
Standard Command
Lockable:
No
Command Code:
0x20
Format:
Mixed: bit-field and 2’s complement
Data Bytes:
1
Units:
N/A
Transfer:
Read Byte
Factory Value:
0x14 (Linear Mode, exponent -12)
Description/Notes:
See Section 8.2 of the PMBus Specification Part II.
supports Linear Mode values for output voltage related commands. The
VOUT_COMMAND
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x21
Format:
Unsigned integer mantissa
Data Bytes:
2
Units:
V
Transfer:
Read/Write Word
Factory Value:
0x0001 (see Description)
Description/Notes:
See Section 8.2 of the PMBus Specification Part II.
In the MAX15301, there are seven possible output voltage ranges based on seven corresponding
internal feedback divider taps. The value of VOUT_COMMAND is retained and read back from volatile
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x22
Format:
Linear
Data Bytes:
2
Units:
V
Transfer:
Read/Write Word
Factory Value:
0x0000 (0V)
Description/Notes:
See Section 13.3 of the PMBus Specification Part II.
Output Voltage Related Commands
VOUT_MODE
The MAX15301 only
VOUT_MODE command is read-only and the value cannot be changed.
The 5-bit exponent for output voltage data is -12, or two’s-complement 10100. This means that
voltage command data sent to and from the MAX15301 using either the 2-byte unsigned integer
mantissa or Direct mantissa formats must be divided by 4096 to determine the actual voltage value.
MAX15301 PMBus Command Set User’s Guide
VOUT_COMMAND mantissa data sent to and from the MAX15301 must be divided by 4096 to
determine the actual voltage value, according to the fixed value of VOUT_MODE
The factory value of 0x0001 (0.244mV) will be overridden during initialization by the hardware (pinstrap) value determined by the resistance to ground detected at the SET pin, unless a specific value
has been written to the User Store. The value of the SET pin resistance is measured only once during
initialization (power-up).
memory, regardless of limitations imposed by the feedback divider range.
New values of VOUT_COMMAND can be written at any time, but large changes (specifically, those
that require a different feedback divider selection;, see Table 7 of the MAX15301 data sheet) will
require the output to be disabled for the feedback divider to change.
VOUT_TRIM
.
Rev 1 Page 10 of 53
In the MAX15301, the value of VOUT_TRIM is summed with the value of VOUT_COMMAND and
VOUT_CAL_OFFSET, and the result is sent to the control loop as the output voltage setpoint.
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x23
Format:
Linear
Data Bytes:
2
Units:
V
Transfer:
Read/Write Word
Factory Value:
0x0000 (0V)
Description/Notes:
See Section 13.4 of the PMBus Specification Part II.
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x24
Format:
Unsigned integer mantissa
Data Bytes:
2
Units:
V
Transfer:
Read/Write Word
Factory Value:
0x0001 (see Description)
Description/Notes:
See Section 13.5 of the PMBus Specification Part II.
erridden during initialization to
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x25
Format:
Unsigned integer mantissa
Data Bytes:
2
Units:
V
Transfer:
Read/Write Word
Factory Value:
0x0001 (see Description)
VOUT_TRIM
The value of VOUT_TRIM is not subtracted from READ_VOUT, so nonzero VOUT_TRIM values will
result in a difference between VOUT_COMMAND and READ_VOUT.
This command is intended to allow an end user of a PMBus device to tailor a specific supply to the
performance requirements of a specific load device, while retaining use of a “nominal” voltage
setpoint for all similar load devices.
VOUT_CAL_OFFSET
In the MAX15301, the value of VOUT_CAL_OFFSET is summed with the value of VOUT_COMMAND
and VOUT_TRIM, and the result is sent to the control loop as the output voltage setpoint.
MAX15301 PMBus Command Set User’s Guide
The value of VOUT_CAL_OFFSET is subtracted from READ_VOUT, so VOUT_CAL_OFFSET values never
result in a difference between VOUT_COMMAND and READ_VOUT.
This command is intended to allow a PMBus device manufacturer or an end user to calibrate the
output voltage of a module (or other power-supply assembly) to match an external reference
instrument during their final-test process.
VOUT_MAX
VOUT_MAX mantissa data sent to and from the MAX15301 must be divided by 4096 to determine the
actual voltage value, according to the fixed value of VOUT_MODE
The factory value of 0x0001 (0.244mV) will be ov
VOUT_COMMAND x 1.10, unless a specific value has been written to the User Store.
VOUT_MARGIN_HIGH
.
Rev 1 Page 11 of 53
Description/Notes:
See Section 13.6 of the PMBus Specification Part II.
In the MAX15301, there are seven possible output voltage ranges based on seven corresponding
high operation, the output will fall at a rate
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x26
Format:
Unsigned integer mantissa
Data Bytes:
2
Units:
V
Transfer:
Read/Write Word
Factory Value:
0x0001 (see Description)
Description/Notes:
See Section 13.7 of the PMBus Specification Part II.
V) will be overridden during initialization to
voltage ranges based on seven corresponding
VOUT_MARGIN_HIGH
VOUT_MARGIN_HIGH mantissa data sent to and from the MAX15301 must be divided by 4096 to
determine the actual voltage value, according to the fixed value of VOUT_MODE
The factory value of 0x0001 (0.244mV) will be overridden during initialization to
VOUT_COMMAND
internal feedback divider taps. The desired value of VOUT_MARGIN_HIGH is retained and read back
from Operating Memory, regardless of hardware limitations imposed by the feedback divider range.
If the MAX15301 is set for margin-high operation prior to the output being enabled, the output will
rise directly to VOUT_MARGIN_HIGH at the rate determined by VOUT_COMMAND/TON_RISE
Likewise, if the output is disabled from margindetermined by -VOUT_COMMAND/TOFF_FALL.
VOUT_MARGIN_LOW
MAX15301 PMBus Command Set User’s Guide
.
x 1.05, unless a specific value has been written to the User Store.
.
VOUT_MARGIN_LOW mantissa data sent to and from the MAX15301 must be divided by 4096 to
determine the actual voltage value, according to the fixed value of VOUT_MODE
The factory value of 0x0001 (0.244
VOUT_COMMAND x 0.95, unless a specific value has been written to the User Store.
In the MAX15301, there are seven possible output
internal feedback divider taps. The desired value of VOUT_MARGIN_LOW is retained and read back
from Operating Memory, regardless of hardware limitations imposed by the feedback divider range.
If the MAX15301 is set for margin-low operation prior to the output being enabled, the output will
rise directly to VOUT_MARGIN_LOW at the rate determined by VOUT_COMMAND/TON_RISE
Likewise, if the output is disabled from margin-low operation, the output will fall at a rate determined
by -VOUT_COMMAND/
.
.
TOFF_FALL.
Rev 1 Page 12 of 53
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x27
Format:
Linear
Data Bytes:
2
Units:
mV/μs (or V/ms, kV/s)
Transfer:
Read/Write Word
Factory Value:
0x9B33 (0.1V/ms, see Description)
Description/Notes:
See Section 13.8 of the PMBus Specification Part II.
Feedback
VOUT_TRANSITION_RATE, kV/s
Divider
Min
Max
0
≈ 0.005
≈ 1.171
1
≈ 0.005
≈ 1.323
2
≈ 0.006
≈ 1.519
3
≈ 0.007
≈ 1.782
4
≈ 0.008
≈ 2.16
5
≈ 0.011
≈ 2.736
6
≈ 0.015
≈ 3.725
7
≈ 0.023
≈ 5.862
based on actual
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x28
Format:
Linear
Data Bytes:
2
Units:
mΩ (or mV/A)
Transfer:
Read/Write Word
Factory Value:
0x0000 (0mΩ)
Description/Notes:
See Section 13.9 of the PMBus Specification Part II.
It is also important to calibrate READ_IOUT using IOUT_CAL_GAIN and IOUT_CAL_OFFSET to achieve
VOUT_TRANSITION_RATE
To achieve output voltage slew-rate control, the MAX15301 has an 8-bit timer with approximately
243ns resolution. When the timer expires, the 12-bit voltage setpoint is incremented or decremented
until the setpoint reaches its final value. This limits the minimum and maximum possible slew-rates
for each feedback divider range as follows:
MAX15301 PMBus Command Set User’s Guide
For each divider range, the minimum transition rate is also the resolution (minimum step size).
The desired value of VOUT_TRANSITION_RATE is retained in memory, regardless of hardware
limitations imposed by the feedback divider range, but the read-back value is
hardware register settings.
If a commanded value of VOUT_TRANSITION_RATE exceeds the maximum possible slew-rate for the
feedback divider range, the MAX15301 sets the slew-rate control timer to zero, and the output
voltage setpoint is updated to the new setpoint value immediately and without delay. In this case,
VOUT_TRANSITION_RATE will read back as 0mV/μs to avoid a divide-by-zero operation.
VOUT_DROOP
The MAX15301 uses low-pass filtered inductor DCR current-sense information (i.e. the READ_IOUT
signal) to establish the load-line characteristic according to the VOUT_DROOP value. Because of this
low-pass filtering of the load current information, there will be some settling time in the output
voltage positioning when VOUT_DROOP is non-zero.
Rev 1 Page 13 of 53
accurate adaptive voltage positioning results with the VOUT_DROOP command.
the VOUT_DROOP command before sending
VOUT_DROOP
Note that VOUT_DROOP can accept negative resistance values, allowing a user to compensation for
resistive losses between the output voltage remote sense point and the load, if desired. (Setting
VOUT_DROOP to a negative value will case output voltage to rise with increasing load.)
Wait at least 500μs for execution after sending
additional PMBus commands.
MAX15301 PMBus Command Set User’s Guide
Rev 1 Page 14 of 53
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x33
Format:
Linear
Data Bytes:
2
Units:
kHz
Transfer:
Read/Write Word
Factory Value:
0x0258 (see Description)
Description/Notes:
See Section 14.4 of the PMBus Specification Part II.
NC pin resistance is measured only once
applied after enabling the output, the PWM will synchronize to the external clock, but
If the external clock crosses the 475kHz boundary while regulating, unexpected results or output
INTERLEAVE
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x37
Format:
4 x 4-bit unsigned integer “nibbles”
Data Bytes:
2
Units:
N/A
Transfer:
Read/Write Word
Factory Value:
0x0000 (see Description)
Description/Notes:
See Section 14.7 of the PMBus Specification Part II.
Switching Frequency and PWM Commands
FREQUENCY_SWITCH
The factory value of 0x0258 (600kHz) will be overridden during initialization by the hardware (pinstrap) value determined by the resistance to ground detected at the SYNC pin, unless a specific value
has been written to the User Store. The value of the SY
during initialization (power-up).
The MAX15301 can also synchronize to an external clock at the SYNC input. If the external clock is
present at or before power-up, the SYNC resistance reading will fail and FREQUENCY_SWITCH will be
set to 300kHz.
The MAX15301 has two different PWM “speed modes” to support FREQUENCY_SWITCH values at or
below 475kHz, and above 475kHz. It is important to ensure that FREQUENCY_SWITCH is set, either by
PMBus command or by successful resistor pin-strap, to a value that is within ±10% of the expected
external clock frequency.
MAX15301 PMBus Command Set User’s Guide
If the external clock is present at the time of output enable, the operating memory value of
FREQUENCY_SWITCH will be updated to reflect the external clock frequency. If the external clock is
FREQUENCY_SWITCH will not be updated.
voltage transients may result.
The actual switching frequency can be obtained using the READ_FREQUENCY command.
Wait at least 10ms for execution after sending the FREQUENCY_SWITCH command before sending
additional PMBus commands.
The INTERLEAVE command determines the phase delay of the MAX15301, measured from the rising
edge of an external clock applied at SYNC to the center of the PWM positive pulse.
The factory value of 0x0000 (zero degrees phase shift) will be overridden during initialization by the
hardware (pin-strap) value determined by the resistances to ground detected at the ADDR0 and
c
c
Because the MAX15301 has dual-edge modulation, the rising and falling edges of the PWM waveform both “move”
relative to the center of the high-side switch on-time.
Rev 1 Page 15 of 53
ADDR1 pins, unless a non-zero value of INTERLEAVE has been written to the User Store. The value of
), the INTERLEAVE command will show unexpected
set a “Group ID Number.” Both nibbles of the high byte of INTERLEAVE can be used
Reference:
Standard Command
Lockable:
Yes
Command Code:
0x5E
Format:
Unsigned integer mantissa
Data Bytes:
2
Units:
V
Transfer:
Read/Write Word
Factory Value:
0x1135 (see Description)
Description/Notes:
See Section 15.32.1 of the PMBus Specification Part II.
POWER_GOOD_ON mantissa data sent to and from the MAX15301 must be divided by 4096 to
The factory value of 0x1135 (1.080V) will be overridden during initialization to
INTERLEAVE
the ADDR0 and ADDR1 pin resistance is measured only once during initialization (power-up).
Because the MAX15301 uses one of two different PWM “speed modes” depending on the switching
frequency selected (see FREQUENCY_SWITCH
results if switching frequency crosses the 475kHz speed-mode boundary after initialization.
The MAX15301 includes enhancements beyond the PMBus specification INTERLEAVE command
functionality:
• Setting the “Number In Group” to zero will be interpreted by the MAX15301 as 16 possible
phases. This allows phase-spreading in 22.5º increments.
• The low nibble of the high byte of INTERLEAVE contains the “Group ID Number” per the
PMBus specification, but this is a value that has no function and no dependent parameters in
either the MAX15301 device or in the PMBus specification. As a result, it is not necessary to
separately or together as “scratchpad” data, if desired.
Output Voltage Sequencing Commands
MAX15301 PMBus Command Set User’s Guide
POWER_GOOD_ON
determine the actual voltage value, according to the fixed value of VOUT_MODE.
In the MAX15301, there are seven possible output voltage ranges based on seven corresponding
internal feedback divider taps. The MAX15301 hardware has 8-bit resolution for the power-good
threshold within each of these seven ranges.
The desired value of POWER_GOOD_ON is retained in memory, regardless of limitations imposed by
the feedback divider range and the 8-bit fault limit resolution, but the read-back value is based on
actual hardware register settings.
VOUT_COMMAND x 0.95, unless a specific value has been written to the User Store.
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