PC87364-XXXSLASHVLA datasheet(42/180 Pages) NSC

42 / 180 page

2.0 Device Architecture and Configuration (Continued)

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2.6

LED OPERATION AND STATES

The device supports up to two LEDs, depending on Pin 25 and Pin 26 Function Select (bits 1-2 and bit 3) of the SIOCFA

, when in power-on state. The device also provides modes for hardware LED control. This enables the LEDs to support fea-

tures such as power and error indication.

The LEDs may be operated in software, hardware1 or hardware 2 modes. These modes are set by LED Mode Control (bits

2 and 3) of the SIOCFB register. Each LED can be set to On, Off or to blink at different rates by means of bits 0-2 (LED1)

and bits 3-5 (LED2) of the SIOCFC register. When in power-on state (both VDD and VSB exist), the LEDs are software-con-

trolled. When in power fail state (no VSB and no VDD) the LEDs are off. Table 14 shows the effect of hardware modes 1 and

2 on LED operation that override the above rules.

Table 14. Hardware Modes 1 and 2 Effect on LED Operation

2.7

POWER SUPPLY CONTROL AND LED CONFIGURATION

A combination of two strap pins (Power Supply and LED Configuration 0 and 1, PSLDC0,1, pins 99 and 107 respectively)

determines the configuration of the power supply control pins and LEDs. Both pins 99 and 107 have weak pull-downs, and

are sampled on VSB power-up reset. Table 15 describes how they affect the chip configuration.

Table 15. PSLDC0,1 Conﬁguration Options

2.8

The following abbreviations are used to indicate the Register Type:

R/W = Read/Write

R = Read from a speciﬁc address returns the value of a speciﬁc register. Write to the same address is to a different

W=Write

RO = Read Only

R/W1C = Read/Write 1 to Clear. Writing 1 to a bit clears it to 0. Writing 0 has no effect.

Mode

System State

LED1

LED2

Hardware 1

(SIOCFB, bits 3-2=01)

VSB power-up reset

Off

1 Hz blink, 50% duty cycle

Power off (VSB,noVDD)

Software-controlled

1 Hz blink, 50% duty cycle

Hardware 2

(SIOCFB, bits 3-2=10)

ACPI mode and

Sleep State 3

Software-controlled

ACPI mode, Sleep State 5,

bit 6 = 1 in SIOCFC register

and Power Supply Control

enabled

Software-controlled

ACPI mode, any other

conﬁguration

Off

Legacy mode and power off

(no VDD)

Off

PSLDC0

(Pin 99)

PSLDC1

(Pin 107)

Power Supply Control

LED2

Enabled (default)

Not selected (default)

Disabled

Selected

Disabled

Not selected

Enabled

Selected

PC87364-XXX/VLA датащи(PDF) 42 Page - National Semiconductor (TI)

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