TC655EUNTR データシートの表示（PDF） - Microchip Technology

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TC655EUNTR

Dual SMBus™ PWM Fan Speed Controllers With Fan Fault Detection

Microchip Technology 

TC654/TC655

6.0 REGISTER SET

The TC654/TC655 devices contain 9 registers that pro-

vide a variety of data and functionality control to the

outside system. These registers are listed below in

Table 6-1. Of key importance is the command byte

information, which is needed in the read and write pro-

tocols in order to select the individual registers.

TABLE 6-1: COMMAND BYTE ASSIGNMENTS

Register

Command Read Write POR Default State

Function

RPM1

0000 0000

X

—

0 0000 0000 RPM Output 1

RPM2

0000 0001

X

—

0 0000 0000 RPM Output 2

FAN_FAULT1

0000 0010

X

X

0000 1010

Fan Fault 1 Threshold

FAN_FAULT2

0000 0011

X

X

0000 1010

Fan Fault 2 Threshold

CONFIG

0000 0100

X

X

0000 1010

Configuration

STATUS

0000 0101

X

—

00X0 0X00

Status. See Section 6.4, Status

Register explanation of X

DUTY_CYCLE

0000 0110

X

X

0000 0010

Fan Speed Duty Cycle

MFR_ID

0000 0111

X

—

0101 0100

Manufacturer Identification

VER_ID

0000 1000

X

—

0000 000X

Version Identification:

(X = ‘0’ TC654, X = ‘1’ TC655)

6.1 RPM-OUTPUT1 & RPM-OUTPUT2

Registers (RPM1 & RPM2)

As discussed in Section 4.7, fan current pulses are

detected at the SENSE1 and SENSE2 inputs of the

TC654/TC655 device. The current pulse information is

used to calculate the fan RPM. The fan RPM data for

fans 1 & 2 is then written to registers RPM1 and RPM2,

respectively. RPM1 and RPM2 are 9-bit registers that

provide the RPM information in 50 RPM (8-bit) or

25 RPM (9-bit) increments. This is selected via RES (bit

6<0>) in the Configuration Register, with ‘0’ = 50 RPM

and ‘1’ = 25 RPM. The default state is zero (50 RPM).

The maximum fan RPM value that can be read is

12775 RPM. If this value is exceeded, R2CO (bit 4<0>)

and R1CO (bit 3<0>) in the Status Register will be set

to a '1' to indicate that a counter overflow of the respec-

tive RPM register has occurred. Register 6-1 shows the

RPM output register 9-bit format.

REGISTER 6-1: RPM OUTPUT REGISTERS (RPM1 & RPM2)

D(8)

D(7)

D(6)

D(5)

D(4)

D(3)

D(2)

D(1)

D(0)

RPM

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

25

0

0

0

0

0

0

0

1

0

50

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

1

1

1

1

1

1

1

1

0

12750

1

1

1

1

1

1

1

1

1

12775

 2002 Microchip Technology Inc.

DS21734A-page 17

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