Datasheet
PMBus 5-Channel Power-Supply Manager
and Intelligent Fan Controller
MAX34441
14
Table 1. PMBus Command Codes
Detailed Description
The MAX34441 is a highly integrated system monitor
based upon a 4MHz, 16-bit, MAXQ
M
microcontroller with
factory-programmed functionality to monitor up to five
power supplies and a system cooling fan. The device
provides power-supply closed-loop control, fan-speed
monitoring, and local/remote thermal-sensing facilities.
The power-supply manager monitors the power-supply
output voltage and constantly checks for user-pro-
grammable overvoltage and undervoltage thresholds. It
also can margin the power-supply output voltage up or
down by a user-programmable level. The margining is
performed in a closed-loop arrangement, whereby the
device automatically adjusts a pulse-width-modulated
(PWM) output and then measures the resultant output
voltage. The power-supply manager can also sequence
the supplies in any order at both power-up and power-
down. With the addition of an external current-sense
amplifier, the device can also monitor currents.
Thermal monitoring can be accomplished using up to six
temperature sensors, including an on-chip thermal sen-
sor, four DS75LV digital thermometers, and a remote ther-
mal diode. Temperature offset can be added to individual
sensors to compensate for thermal differences in a sys-
tem. Communication with the DS75LV temperature sensor
is conducted through a dedicated I
2
C/SMBus interface.
The device also contains closed-loop fan-speed control.
Based on user-programmable settings for fan-control
PWM duty cycles or for fan RPM speeds at particu-
lar temperature breakpoints, the device automatically
adjusts the fan speed in a manner to reduce audible
noise and power consumption.
The device provides ALERT and FAULT output signals.
Host communications are conducted through a PMBus-
compatible communications port. Address input con-
nections are also provided to allow up to four MAX34441
devices to reside on the system’s I/O bus.
MAXQ is a registered trademark of Maxim Integrated
Products, Inc.
CODE COMMAND NAME TYPE
PAGE
0–4
PAGE
5
PAGE
6–11
PAGE
255
NO. OF
BYTES
FLASH
STORED
(NOTE 2)
DEFAULT
VALUE
(NOTE 2)
(NOTE 1)
00h PAGE R/W Byte R/W R/W R/W R/W 1 N 00h
01h OPERATION R/W Byte R/W — — W 1 N 00h
02h ON_OFF_CONFIG R/W Byte R/W R/W R/W R/W 1 Y 1Ah
03h CLEAR_FAULTS Send Byte W W W W 0 N —
10h WRITE_PROTECT R/W Byte R/W R/W R/W R/W 1 N 00h
11h STORE_DEFAULT_ALL Send Byte W W W W 0 N —
12h RESTORE_DEFAULT_ALL Send Byte W W W W 0 N —
19h CAPABILITY Read Byte R R R R 1 N 00h/10h
20h VOUT_MODE Read Byte R R R R 1 FIXED 40h
25h VOUT_MARGIN_HIGH R/W Word R/W — — — 2 Y 0000h
26h VOUT_MARGIN_LOW R/W Word R/W — — — 2 Y 0000h
2Ah VOUT_SCALE_MONITOR R/W Word R/W — — — 2 Y 7FFFh
38h IOUT_CAL_GAIN R/W Word R/W — — — 2 Y 0000h
3Ah FAN_CONFIG_1_2 R/W Byte — R/W — — 1 Y 00h
3Bh FAN_COMMAND_1 R/W Word — R/W — — 2 Y FFFFh
40h VOUT_OV_FAULT_LIMIT R/W Word R/W — — — 2 Y 7FFFh
42h VOUT_OV_WARN_LIMIT R/W Word R/W — — — 2 Y 7FFFh
43h VOUT_UV_WARN_LIMIT R/W Word R/W — — — 2 Y 0000h
44h VOUT_UV_FAULT_LIMIT R/W Word R/W — — — 2 Y 0000h
46h IOUT_OC_WARN_LIMIT R/W Word R/W — — — 2 Y 7FFFh
4Ah IOUT_OC_FAULT_LIMIT R/W Word R/W — — — 2 Y 0000h
4Fh OT_FAULT_LIMIT R/W Word — — R/W — 2 Y 7FFFh