W83627DHG Datasheet, PDF (52/268 Pages) Winbond – WINBOND LPC I/O

W83627DHG
7.6.2 Fan Speed Control
The W83627DHG has four output pins for fan control, each of which offers PWM duty cycle and DC
voltage to control the fan speed. The output type (PWM or DC) of each pin is configured by Bank0
Index 04h, bits 1 ~ 0; Index 12h, bit 0; and Index 62h, bit 6.
For PWM, the duty cycle is programmed by eight-bit registers at Bank0 Index 01h, Index 03h, Index
11h and Index 61h. The duty cycle can be calculated using the following equation:
Dutycycle(%) = ^{Programmed 8 - bit Register Value} ×100%
255
The default duty cycle is FFh, or 100%. The PWM clock frequency is programmed at Bank0 Index 00h,
Index 02h, Index 10h and Index 60h.
For DC, the W83627DHG has a six bit digital-to-analog converter (DAC) that produces 0 to 3.3 Volts
DC. The analog output is programmed at Bank0 Index 01h, Index 03h, Index 11h and Index 61h. The
analog output can be calculated using the following equation:
OUTPUT Vo⁼lta^Age^V(^CV^C) ^{× Programmed 6 - bit Register Value`}
64
The default value is 111111YY, or nearly 3.3 V, and Y is a reserved bit.
Publication Release Date: Aug, 22, 2007
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Version 1.4