EMC2302 datasheet(28/44 Pages) SMSC

28 / 44 page

Dual RPM-Based PWM Fan Controller

Datasheet

Revision 1.1 (10-12-09)

SMSC EMC2302

DATASHEET

‘0’ (default) - An error condition on Fan X will not cause the ALERT# pin to be asserted, however

the status registers will be updated normally.

‘1’ - An error condition (Stall, Spin Up, Drive Fail) on Fan X will cause the ALERT# pin to be

asserted.

5.5

PWM Configuration Registers

The PWM Config registers control the output type and polarity of all PWM outputs.

5.5.1

PWM Polarity Config - 2Ah

Bit 1 - POLARITY2 - Determines the polarity of PWM 2.

Bit 0 - POLARITY1 - Determines the polarity of PWM 1.

‘0’ (default) - the Polarity of the PWM driver is normal. A drive setting of 00h will cause the output

to be set at 0% duty cycle and a drive setting of FFh will cause the output to be set at 100% duty

cycle.

‘1’ - The Polarity of the PWM driver is inverted. A drive setting of 00h will cause the output to be

set at 100% duty cycle and a drive setting of FFh will cause the output to be set at 0% duty cycle.

5.5.2

PWM Output Config - 2Bh

Bit 1 - PWM2_OT - Determines the output type of PWM 2 driver.

Bit 0 - PWM1_OT - Determines the output type of the PWM 1 driver.

‘0’ (default) - The PWM 1 output is configured as an open drain output.

‘1’ - The PWM 1 output is configured as a push-pull output.

5.6

PWM Base Frequency Register

The PWM Base Frequency register determines the base frequency that is used with the PWM Divide

its respective divide ratio (see Section 5.8).

Controls the base frequency of PWM drivers 1-3 2

Table 5.5 PWM Configuration Registers

ADDR

R/W

DEFAULT

2Ah

R/W

PWM Polarity

Config

---

POLARITY

00h

2Bh

R/W

PWM Output

Config

PWM2_OT

PWM1_OT

00h

Table 5.6 PWM Base Frequency Register

ADDR

R/W

B5B4B3B2B1B0

DEFAULT

2Dh

R/W

PWM Base

Frequency

PWM_

BASE

2_1

PWM_

BASE

2_0

PWM_

BASE

1_1

PWM_

BASE

1_0

00h

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