Rainbow Electronics LM87 - Manual (Page 28)

Functional Description
(Continued)
Bit Name Read/Write Description
4-5 FAN1 RPM
Control
Read/Write FAN1 Speed Control.
< 5:4 > = 00 - divide by 1;
< 5:4 > = 01 - divide by 2;
< 5:4 > = 10 - divide by 4;
< 5:4 > = 11 - divide by 8.
6-7 FAN2 RPM
Control
Read/Write FAN2 Speed Control.
< 7:6 > = 00 - divide by 1;
< 7:6 > = 01 - divide by 2;
< 7:6 > = 10 - divide by 4;
< 7:6 > = 11 - divide by 8.
13.13 VID4 Register — Address 49h
Power on default – < 7:1 > = 100 000, < 0 > = VID4.
Bit Name Read/Write Description
0 VID4 Read Only Bit 4 of VID data from the CPU or power supply that indicates the operating voltage
(e.g. 1.5 V to 2.9 V).
1-7 Reserved Read/Write
13.14 Configuration Register 2 — Address 4Ah
Power on default – < 7:0 > = 0000 0000 binary
Bit Name Read/Write Description
0 Thermal INT#
Mask
Read/Write When this bit is set to 1, thermal error events will not affect the INT# interrupt
output. THERM# outputs will still function normally.
1 Local Temp.
Register Write
Once Bit
Read/Write
Once
When set to 1, this bit locks in the value set in the Internal Temp. high limit register
at 0x13h. The value cannot be changed until a power on reset is performed, or the
chip is re-Initialized by writing a 1 to Bit 7 of Configuration Register 1 (Register
40h).
2 Remote Temp.
Register Write
Once Bit
Read/Write
Once
When set to 1, this bit locks in the value set in the External Temp. high limit
register at 0x14h. The value cannot be changed until a power on reset is
performed, or the chip is re-Initialized by writing a 1 to Bit 7 of Configuration
Register 1 (Register 40h).
3 THERM# Interrupt
Mode
Read/Write When set to 0, the THERM# output functions in Default mode. When set to 1, the
THERM# output functions in ACPI mode.
4-5 Reserved
6 IRQ3 Enable Read/Write When set to 1, VID3/IRQ3 is enabled as an active high interrupt input (if the
IRQEN bit is set in bit 7 of the Channel Mode Register).
7 IRQ4 Enable Read/Write When set to 1, VID4/IRQ4 is enabled as an active high interrupt input (if the
IRQEN bit is set in bit 7 of the Channel Mode Register).
13.15 Interrupt Status Register 1 Mirror — Address 4Ch
Power on default – < 7:0 > = 0000 0000 binary
Bit Name Read Only Description
0 +2.5Vin Read Only A one indicates a High or Low limit has been exceeded.
1 Vccp1 Read Only A one indicates a High or Low limit has been exceeded.
2 Vcc Read Only A one indicates a High or Low limit has been exceeded.
3 +5Vin Read Only A one indicates a High or Low limit has been exceeded.
4 Int. Temp. Read Only A one indicates a High or Low limit has been exceeded.
5 Ext. Temp. Read Only A one indicates a High or Low limit has been exceeded.
LM87
www.national.com 28