ADT7476AARQZ-R datasheet(19/69 Pages) ONSEMI

19 / 69 page

ADT7476A

www.onsemi.com

and null it out using the offset registers. The offset registers

automatically add a twos complement 8-bit reading to every

temperature measurement.

Changing Bit 1 of Configuration Register 5 (0x7C)

changes the resolution and therefore, the range of the

temperature offset as either having a −63

°C to +127°C range

with a resolution of 1

°C or having a −63°C to +64°C range

with a resolution of 0.5

°C. This temperature offset can be

used to compensate for linear temperature errors introduced

by noise.

Table 16. TEMPERATURE OFFSET REGISTERS

Description

Default

0x70

Remote 1 Temperature Offset

0x00 (0

°C)

0x71

Local Temperature Offset

0x00 (0

°C)

0x72

Remote 2 Temperature Offset

0x00 (0

°C)

ADT7463/ADT7476A Backwards Compatible Mode

By setting Bit 0 of Configuration Register 5 (0x7C), all

temperature measurements are stored in the zone

temperature reading registers (0x25, 0x26, and 0x27) in

twos complement in the −63

°C to +127°C range. The

temperature limits must be reprogrammed in twos

complement.

If a twos complement temperature below −63

°C is

entered, the temperature is clamped to −63

°C. In this mode,

the diode fault condition remains −128

°C = 1000 0000,

while in the extended temperature range (−63

°C to +191°C),

the fault condition is represented by −64

°C = 0000 0000.

Table 17. TEMPERATURE READING REGISTERS

Description

Default

0x25

Remote 1 Temperature

−

0x26

Local Temperature

−

0x27

Remote 2 Temperature

−

0x77

Extended Resolution 2

0x00

Table 18. EXTENDED RESOLUTION TEMPERATURE

MEASUREMENT REGISTER BITS

Bit

Mnemonic

Description

[7:6]

TDM2

Remote 2 Temperature LSBs

[5:4]

LTMP

Local Temperature LSBs

[3:2]

TDM1

Remote 1 Temperature LSBs

Temperature Limit Registers

Associated with each temperature measurement channel

are high and low limit registers. Exceeding the programmed

high or low limit causes the appropriate status bit to be set.

Exceeding either limit can also generate SMBALERT

interrupts (depending on the way the interrupt mask register

is programmed and assuming that SMBALERT is set as an

output on the appropriate pin).

Table 19. TEMPERATURE LIMIT REGISTERS

Description

Default

0x4E

Remote 1 Temperature Low Limit

0x81

0x4F

Remote 1 Temperature High Limit

0x7F

0x50

Local Temperature Low Limit

0x81

0x51

Local Temperature High Limit

0x7F

0x52

Remote 2 Temperature Low Limit

0x81

0x53

Remote 2 Temperature High Limit

0x7F

Reading Temperature from the ADT7476A

It is important to note that temperature can be read from

the ADT7476A as an 8-bit value (with 1

°C resolution) or as

a 10-bit value (with 0.25

°C resolution). If only 1°C

resolution is required, the temperature readings can be read

back at any time and in no particular order.

If the 10-bit measurement is required, this involves a

2-register read for each measurement. Extended Resolution

temperature reading registers to be frozen until all

temperature reading registers have been read from. This

prevents an MSB reading from being updated while its two

LSBs are being read and vice versa.

Additional ADC Functions for Temperature

Measurement

A number of other functions are available on the

ADT7476A to offer the system designer increased

flexibility.

Turn-off Averaging

For each temperature measurement read from a value

the results averaged, before being placed into the value

measurement. Setting Bit 4 of Configuration Register 2

(0x73) turns averaging off. The default round robin cycle

time takes 146.5 ms.

Table 20. CONVERSION TIME WITH AVERAGING

DISABLED

Channel

Measurement Time (ms)

Voltage Channels

0.7

Remote Temperature 1

Remote Temperature 2

Local Temperature

1.3

When Bit 7 of Configuration Register 6 (0x10) is set, the

default round robin cycle time increases to 240 ms.

Table 21. CONVERSION TIME WITH AVERAGING

ENABLED

Channel

Measurement Time (ms)

Voltage Channels

Remote Temperature

Local Temperature

ADT7476AARQZ-R Datasheet(PDF) 19 Page - ON Semiconductor

ADT7476AARQZ-R Datasheet(HTML) 19 Page - ON Semiconductor

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69

Datasheet Download

Link URL