ADT7490ARQZ-R7 datasheet(57/75 Pages) ONSEMI

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Table 47. Register 0x5C, Register 0x5D, and Register 0x5E — PWM1, PWM2, and PWM3 Configuration Registers

(Power−On Default = 0x62)

Bit No.

Mnemonic

R/W (Note 1)

Description

[2:0]

SPIN

R/W

These bits control the startup timeout for PWMx. The PWM output stays high until two valid

TACH rising edges are seen from the fan. If there is not a valid TACH signal during the fan

TACH measurement directly after the fan startup timeout period, the TACH measurement reads

0xFFFF and Interrupt Status Register 2 reflects the fan fault. If the TACH minimum high and

low bytes contain 0xFFFF or 0x0000, then the Interrupt Status Register 2 bit is not set, even if

the fan has not started.

Bit Code

Startup Time

000

001

010

011

100

101

110

111

No startup timeout

100 ms

250 ms (default)

400 ms

667 ms

1 sec

2 sec

4 sec

[3]

ALT

R/W

Use alternative behavior setting options in Bits [7:5] below for PWMx by setting this bit to 1.

Default = 0.

[4]

INV

R/W

This bit inverts the PWM output. The default is 0, which corresponds to a logic high output for

100% duty cycle. Setting this bit to 1 inverts the PWM output, so a 100% duty cycle

corresponds to a logic low output.

[7:5]

BHVR

(Note 2)

R/W

These bits assign each fan to a particular temperature sensor for localized cooling. Setting Bit 3

to Logic 1 in this register chooses whether the default of alternative behavior option is selected.

Default Behavior Bits

Alternative Behavior Bits (Note 2)

000 = Remote 1 temperature controls

PWMx (automatic fan control mode).

000 = PECI0 reading controls PWMx

(automatic fan control mode).

001 = Local temperature controls PWMx

(automatic fan control mode).

001 = PECI1 reading controls PWMx

(automatic fan control mode).

010 = Remote 2 temperature controls

PWMx (automatic fan control mode).

010 = PECI2 reading controls PWMx

(automatic fan control mode).

011 = PWMx runs full speed (default).

011 = PECI3 reading controls PWMx

(automatic fan control mode).

100 = PWMx disabled.

100 = Reserved. If selected, fans run at 100%

duty cycle.

101 = Fastest speed calculated by local

and Remote 2 temperature controls PWMx.

101 = Fastest of all four PECI channels. Fastest

speed calculated by all four PECI readings.

110 = Fastest speed calculated by all three

temperature channel controls PWMx.

110 = Reserved. If selected, fans run at 100%

duty cycle.

111 = Manual mode. PWM duty cycle

registers (Register 0x30 to Register 0x32)

become writable.

111 = Fastest speed calculated by all of the

thermal zones (Local, Remote 1, Remote 2,

and PECI temperatures).

1. This register becomes read-only when the Configuration Register 1 (0x40) LOCK bit is set to 1. Any subsequent attempts to write to this

2. When REPLACE mode is selected, (Register 0x36, Bit 4 set to 1) PWM1 is automatically configured for the alternative behavior setting.

Table 48. Temperature TRANGE/PWM Frequency Registers

R/W (Note 1)

Description

Power−On Default

0x5F

R/W

Remote 1 TRANGE/PWM1 frequency.

0xC4

0x60

R/W

Local TRANGE/PWM2 frequency.

0xC4

0x61

R/W

Remote 2 TRANGE/PWM3 frequency.

0xC4

1. These registers become read-only when the Configuration Register 1 (0x40) LOCK bit is set. Any further attempts to write to these registers

have no effect.

ADT7490ARQZ-R7 Datasheet(PDF) 57 Page - ON Semiconductor

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