Datasheet

Data Sheet ADT7470

Rev. E | Page 33 of 40

Table 36. Register 0x58 to Register 0x67. Fan Tachometer Limit Registers.

0x58 Read/Write Tach 1 min low byte 0xFF

0x59 Read/Write Tach 1 min high byte 0xFF

0x5A Read/Write Tach 2 min low byte 0xFF

0x5B Read/Write Tach 2 min high byte 0xFF

0x5C Read/Write Tach 3 min low byte 0xFF

0x5D Read/Write Tach 3 min high byte 0xFF

0x5E Read/Write Tach 4 min low byte 0xFF

0x5F Read/Write Tach 4 min high byte 0xFF

0x60 Read/Write Tach 1 max low byte 0x00

0x61 Read/Write Tach 1 max high byte 0x00

0x62 Read/Write Tach 2 max low byte 0x00

0x63 Read/Write Tach 2 max high byte 0x00

0x64 Read/Write Tach 3 max low byte 0x00

0x65 Read/Write Tach 3 max high byte 0x00

0x66 Read/Write Tach 4 max low byte 0x00

0x67

Read/Write

Tach 4 max high byte

0x00

Exceeding any of the tach min limit registers shown in Table 36 by 1 indicates that the fan is running too slowly or has stalled.

The appropriate status bit is set in Interrupt Status Register 2 to indicate the fan failure.

Exceeding any of the tach max limit registers by 1 indicates that the fan is too fast. The appropriate status bit is set in Interrupt Status

Table 37. Register 0x68. PWM1/PWM2 Configuration Register (Power-On Default = 0x00).

Bit Name Read/Write Description

[0] N/A Set to 0 (default).

[1] N/A Set to 0 (default).

[2] N/A Set to 0 (default).

[3] N/A Set to 0 (default).

[4] INV2 Read/Write Setting this bit to 1 inverts the PWM2 output. Default = 0.

[5] INV1 Read/Write Setting this bit to 1 inverts the PWM1 output. Default = 0.

[6] BHVR2 Read/Write This bit assigns fan behavior for PWM2 output.

0 = manual fan control mode (PWM duty cycle controlled in software).

1 = automatic fan control mode

[7] BHVR1 Read/Write This bit assigns fan behavior for PWM1 output.

0 = manual fan control mode (PWM duty cycle controlled in software).

1 = automatic fan control mode.