ADT7463ARQZ-R7 datasheet(18/52 Pages) ONSEMI

18 / 52 page

REV. C

–18–

ADT7463

Temperature Measurement Registers

Reg. 0x25 Remote 1 Temperature = 0x80 Default

Reg. 0x26 Local Temperature = 0x80 Default

Reg. 0x27 Remote 2 Temperature = 0x80 Default

Reg. 0x77 Extended Resolution 2 = 0x00 Default

<7:6> TDM2 = Remote 2 Temperature LSBs

<5:4> LTMP = Local Temperature LSBs

<3:2> TDM1 = Remote 1 Temperature LSBs

Temperature Measurement 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.

Reg. 0x4E Remote 1 Temp Low Limit = 0x81 Default

Reg. 0x4F Remote 1 Temp High Limit = 0x7F Default

Reg. 0x50 Local Temp Low Limit = 0x81 Default

Reg. 0x51 Local Temp High Limit = 0x7F Default

Reg. 0x52 Remote 2 Temp Low Limit = 0x81 Default

Reg. 0x53 Remote 2 Temp High Limit = 0x7F Default

Reading Temperature from the ADT7463

It is important to note that temperature can be read from the

ADT7463 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. The extended resolution register

(Reg. 0x77) should be read first. This causes all temperature

reading registers to be frozen until all temperature reading regis-

ters have been read from. This prevents an MSB reading from

being updated while its 2 LSBs are being read and vice versa.

ADDITIONAL ADC FUNCTIONS

A number of other functions are available on the ADT7463 to

offer the systems designer increased flexibility.

Turn-Off Averaging

For each temperature measurement read from a value register,

16 readings have actually been made internally and the results

averaged before being placed into the value register. Sometimes

it may be necessary to take a very fast measurement, e.g., of CPU

temperature. Setting Bit 4 of Configuration Register 2 (Reg. 0x73)

turns averaging off. This takes a reading every 13 ms. The mea-

surement itself takes 4 ms.

Single-Channel ADC Conversions

Setting Bit 6 of Configuration Register 2 (Reg. 0x73) places the

ADT7463 into single-channel ADC conversion mode. In this

mode, the ADT7463 can be made to read a single temperature

channel only. If the internal ADT7463 clock is used, the

selected input is read every 1.4 ms. The appropriate ADC chan-

nel is selected by writing to Bits <7:5> of TACH1 Minimum

High Byte Register (0x55).

Bits <7:5> Reg 0x55

Channel Selected

101

Remote 1 Temperature

110

Local Temperature

111

Remote 2 Temperature

Configuration Register 2 (Reg. 0x73)

<4> = 1 Averaging Off

<6> = 1 Single-Channel Convert Mode

TACH1 Minimum High Byte (Reg. 0x55)

<7:5> Selects ADC Channel for Single-Channel Convert Mode

Overtemperature Events

Overtemperature events on any of the temperature channels can

be detected and dealt with automatically in automatic fan speed

control mode. Registers 0x6A to 0x6C are the THERM limits.

When a temperature exceeds its THERM limit, all fans run at

100% duty cycle. The fans stay running at 100% until the

temperature drops below THERM – Hysteresis (this can be

disabled by setting the boost bit in Configuration Register 3,

Bit 2, Register 0x78). The hysteresis value for that THERM

limit is the value programmed into Registers 0x6D, 0x6E

(hysteresis registers). The default hysteresis value is 4

°C.

FANS

THERM LIMIT

TEMPERATURE

100%

HYSTERESIS (�C)

Figure 16. THERM Limit Operation

Rev. 4 | Page 18 of 52 | www.onsemi.com

ADT7463ARQZ-R7 датащи(PDF) 18 Page - ON Semiconductor

ADT7463ARQZ-R7 датащи(HTML) 18 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

датащи скачать

ссылки URL