Detailed Description

The MAX6697 is a precision multichannel temperature

monitor that features one local and six remote tempera-

ture-sensing channels with a programmable alert

threshold for each temperature channel and a program-

mable overtemperature threshold for channels 1, 4, 5,

and 6 (see Figure 1). Communication with the MAX6697

is achieved through the SMBus serial interface and a

dedicated alert pin. The alarm outputs,

OVERT and

ALERT, assert if the software-programmed temperature

thresholds are exceeded.

ALERT typically serves as an

interrupt, while

OVERT can be connected to a fan, sys-

tem shutdown, or other thermal-management circuitry.

ADC Conversion Sequence

In the default conversion mode, the MAX6697 starts the

conversion sequence by measuring the temperature on

channel 1, followed by 2, 3, local channel, 4, 5, and 6.

The conversion result for each active channel is stored

in the corresponding temperature data register.

In some systems, one of the remote thermal diodes may

be monitoring a location that experiences temperature

changes that occur much more rapidly than in the other

channels. If faster temperature changes must be moni-

tored in one of the temperature channels, the MAX6697

allows channel 1 to be monitored at a faster rate than

the other channels. In this mode (set by writing a 1 to bit

4 of the configuration 1 register), measurements of

channel 1 alternate with measurements of the other

channels. The sequence becomes channel 1, channel

2, channel 1, channel 3, channel 1, etc. Note that the

time required to measure all seven channels is consid-

erably greater in this mode than in the default mode.

Low-Power Standby Mode

Standby mode reduces the supply current to less than

15µA by disabling the internal ADC. Enter standby by

setting the STOP bit to 1 in the configuration 1 register.

During standby, data is retained in memory, and the

SMBus interface is active and listening for SMBus com-

mands. The timeout is enabled if a start condition is rec-

ognized on SMBus. Activity on the SMBus causes the

supply current to increase. If a standby command is

received while a conversion is in progress, the conver-

sion cycle is interrupted, and the temperature registers

are not updated. The previous data is not changed and

remains available.

7-Channel Precision Temperature Monitor

6

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PIN

NAME

FUNCTION

9

DXP5

Combined Current Source and A/D Positive Input for Channel 5 Remote Diode. Connect to the anode

remote diode is used. Place a 2200pF capacitor between DXP5 and DXN5 for noise filtering.

10

DXN5

Cathode Input for Channel 5 Remote Diode. Connect the cathode of the channel 1 remote-diode-

connected transistor to DXN5.

11

DXN6

Cathode Input for Channel 6 Remote Diode. Connect the cathode of the channel 1 remote-diode-

connected transistor to DXN6.

12

DXP6

Combined Current Source and A/D Positive Input for Channel 6 Remote Diode. Connect to the anode

remote diode is used. Place a 2200pF capacitor between DXP6 and DXN6 for noise filtering.

13, 14

NC_

No Connect. Must be connected to ground.

15

OVERT

Overtemperature Active-Low, Open-Drain Output. OVERT asserts low when the temperature of

channels 1, 4, 5, and 6 exceeds the programmed threshold limit.

16

Supply Voltage Input. Bypass to GND with a 0.1µF capacitor.

17

ALERT

SMBus Alert (Interrupt), Active-Low, Open-Drain Output. ALERT asserts low when the temperature of

any channel exceeds the programmed ALERT threshold.

18

SMBDATA

SMBus Serial-Data Input/Output. Connect to a pullup resistor.

19

SMBCLK

SMBus Serial-Clock Input. Connect to a pullup resistor.

20

GND

Ground

Pin Description (continued)