Ver: 0.2 Preliminary

Dec 11, 2001

TEL: 886-3-5788833

http://www.gmt.com.tw

11

G771

Global Mixed-mode Technology Inc.

Configuration Byte Functions

The configuration byte register contents are listed in

table 5. Bit 7 (MASK) is used to mask

ALERT inter-

rupt. Bit 6 ( RUN /STOP) is to put the device in software

standby mode. Setting bit 5 (DET_FAN) with logic 1

can activate the detection of fan failure. Logic 1 in bit 4

(EN_TH_SHUT) makes thermal shutdown function

valid and logic 0 disables this function and keep

TH_SHUT pin low. Bit 3~0 forms thermal shutdown

fault queue. The number of faults these bits decided

are listed in table 6.

Thermal Status Byte Functions

The thermal status byte register (02h) (Table 6) indi-

cates which (if any) temperature thresholds have been

exceeded. This byte also indicates whether or not the

ADC is converting and whether there is an open circuit

in the remote diode DXPx-DXN path. After POR, the

normal state of all the flag bits is zero, assuming none

of the alarm conditions are present. The status byte is

cleared by any successful read of the status, unless

the fault persists. Note that the ALERT interrupt latch

is not automatically cleared when the status flag bit is

cleared.

When reading the status byte, you must check for in-

ternal bus collisions caused by asynchronous ADC

timing, or else disable the ADC prior to reading the

status byte (via the RUN /STOP bit in the configura-

tion byte). In one-shot mode, read the status byte only

after the conversion is complete, which is 150ms max

after the one-shot conversion is commanded.

Table 5. Configuration-Byte Bit Assignments

BIT

NAME

POR STATE

FUNCTION

7 (MSB)

MASK

0

Masks all ALERT interrupts when high.

6

RUN

/ STOP

0

Standby mode control bit. If high, the device immediately stops converting and en-

ters standby mode. If low, the device converts in either one-shot or timer mode.

5

DET_FAN

0

Should be 0. Changing this to 1 will cause ALERT function abnormal.

4

EN_TH_SHUT

1

Validation of the fault queue function of thermal shutdown.

3-0

FQ_TH_SHUT

0010b

Fault Queue. Number of faults necessary to detect before setting TH_SHUT output

to avoid false tripping due to noise.

Table 6. Number of Faults assigned by FQ_TH_SHUT

FQ_TH_SHUT

Number of Faults

FQ_TH_SHUT

Number of Faults

0000b

1

1000b

9

0001b

2

1001b

10

0010b

3(Power-up default)

1010b

11

0011b

4

1011b

12

0100b

5

1100b

13

0101b

6

1101b

14

0110b

7

1110b

15

0111b

8

1111b

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