Datasheet

ADT7470 Data Sheet
Rev. E | Page 34 of 40
Table 38. Register 0x69. PWM3/PWM4 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] INV4 Read/Write Setting this bit to 1 inverts the PWM4 output. Default = 0
[5] INV3 Read/Write Setting this bit to 1 inverts the PWM3 output. Default = 0
[6] BHVR4 Read/Write This bit assigns fan behavior for PWM4 output.
0 = manual fan control mode (PWM duty cycle controlled in software).
1 = (automatic fan control mode.
[7] BHVR3
Read/Write
This bit assigns fan behavior for PWM3 output.
0 = manual fan control mode (PWM duty cycle controlled in software).
1 = automatic fan control mode.
Table 39. Register 0x6A to Register 0x6D. PWM
MIN
Duty Cycle Registers (Power-On Default = 0x80 (50% Duty Cycle).
Register Address Read/Write Description
0x6A Read/Write PWM1 min duty cycle.
0x6B Read/Write PWM2 min duty cycle.
0x6C Read/Write PWM3 min duty cycle.
0x6D
Read/Write
PWM4 min duty cycle.
Table 40. PWM
MIN
Duty Cycle Registers Detailed Description
Bit Name Read/Write Description
[7:0] PWM Duty Cycle Read/Write These bits define the PWNMIN duty cycle for PWMx (x = 1 to 4).
0x00 = 0% duty cycle (fan off).
0x40 = 25% duty cycle.
0x80 = 50% duty cycle.
0xFF = 100% PMW max duty cycle (full fan speed).
Table 41. Register 0x6E to Register 0x71. T
MIN
Registers (Power-On Default = 0x5A (90°C)).
Register Address Read/Write Description
0x6E Read/Write Temperature 1 T
MIN
.
0x6F Read/Write Temperature 2 T
MIN
.
0x70 Read/Write Temperature 3 T
MIN
.
0x71 Read/Write Temperature 4 T
MIN
.
Table 41 shows the T
MIN
registers for each thermal zone. When the temperature measured exceeds T
MIN
, the appropriate fan runs at
minimum speed (PWM
MIN
). They increase to maximum speed (PWM
MAX
) at T
MIN
+ 20°C.