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FM3580 数据表(PDF) 6 Page - Fairchild Semiconductor |
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FM3580 数据表(HTML) 6 Page - Fairchild Semiconductor |
6 / 11 page 6 www.fairchildsemi.com FM3580 Rev. A.5 Functional Description Legacy VID Operation During standard operation FM3580 (the device) will pass data from the I[0:4] inputs (I-Port) or data from an internal register SOPR-A or data from an internal register SOPR-B to the Y[0:4] outputs (Y-Port). Logic is implemented through a set of multiplex- ers. All the signals and the control involved in the VID operation are explained below. Output Port (Y-Port): Y[0-4] This Y-Port output forms the power management signals to determine the CPU power level and is typically connected to the motherboard DC-DC converter. As mentioned before this Y-Port is a multiplexed output of either the I-Port input or data from one of the two internal registers (SOPR-A ; SOPR-B). Choice of which one is selected is determined by Mux_Sel input signal and Bits[7:6] of SOPR-A/SOPR-B registers. Note that Bit7 and Bit 6 are defined to be common for both SOPR-A and SOPR-B regis- ters. Rest of the bits (Bit5:0) are defined to be separate. At power up the default path is from I-Port to Y-Port till a valid SMBus write command is issued to set Bits[7:6] at which point the Y-Port output is determined by the combined status of Mux_Sel input signal and the Bit[7:6] values. The multiplexer only updates when an SMBus stop condition is observed. The output type of the Y-Port can be configured for either an Open-drain type or TTL type using Level input. Y-Port is always active. Refer Multiplexer Block diagram. Table.1 summarizes above description. Input Port (I-Port): I[0-4] The I-port values are generated externally on the PC motherboard and may be either hardwired or driven by another device. Internal pull-up resistors are provided on the I-Port to accommodate this device being driven by an open-drain output driver. Level Input This input controls the output type of the Y-Port signals and Non_Mux_Out signal. If Level signal is connected to Ground, then the Y-Port outputs are actively driven to 2.5V and Non_Mux_Out signal is actively driven up to VCC. If Level signal is connected to V CC (or left unconnected), then the Y-Port signals and Non_Mux_Out signal operate as open-drain outputs. Level input has an internal pull-up resistor and hence can be left unconnected to recognize a logic high at its input. Non_Mux_Out Output This is an output signal and it reflects the Bit4 of either SOPR-A or SOPR-B register. Like the Y-Port, Bit[7:6] values determine the selection of either Bit 4 of SOPR-A or Bit4 of SOPR-B register. The Non_Mux_Out output is transparent when the Mux_sel signal is at logic 0 and will latch data on the rising edge of the Mux_sel signal. Mux_Sel Input This is an input signal and is used to select data for Y-Port outputs. If this signal is set to logic 1, I-Port data is driven on the Y-Port and when set to logic 0 (and /Override = 1), data from one of the two internal non-volatile registers (SOPR-A or SOPR-B) are driven on the Y0-4 outputs. /Override Input This is an input signal and when set to logic low (and Mux_Sel = 0), will cause all the Y-Port outputs and Non_Mux_Out output to be set to Logic Low. VID Registers Description FM3580 has 3 internal registers, viz. SOPR-A, SOPR-B and PIPR for VID function. These registers are made up of a combination of read-only, write-only and read-write bits. Serial Output Port Register A (SOPR -A) This is a 8-bit read-write register that contains 5-bit data for output Y-Port, 1-bit data for Non_Mux_Out Output and two multiplexer select bits. This register can be read and written through SMBus and is at address 0x00h. Refer SOPR-A/B diagram. Serial Output Port Register B (SOPR -B) This is a 8-bit read-write register that contains 5-bit data for output Y-Port, 1-bit data for Non_Mux_Out Output and two multiplexer select bits. This register can be read and written through SMBus and is at address 0x01h. Refer SOPR-A/B diagram. Parallel Input Port Register (PIPR) This is a 8-bit read-only register. Bits[7:5] are reserved and are set to read “0” always. Bits[4:0] contain latched I-Port value. I-port data is latched into this register on the first clock after a “START” condition is detected on the SMBus. This insures valid value be read from this register always. This register can only be read through SMBus and is at address 0x02h. Refer PIPR diagram. SMBus Interface FM3580 uses standard SMBus protocol to communicate with external interface (system). Various blocks and features of this device are accessible through the SMBus interface. This device supports both byte and block reads as defined in the SMBus specification. VID block is accessed through byte-write and block-read commands, while the Security block is accessed through block-read/write commands. Device Addressing FM3580 uses 7 bit SMBus addressing. If the ASEL input is ‘1,’ then the device will respond to 1001-110 address. If the ASEL input is ‘0,’ then the device will respond to 0110-111 address. The address byte is the first byte of data sent after a start condition. The device will not respond to the general call address 0000-000. SOPR-A Register Write Operation (Byte) Following is the SMBus command sequence to write SOPR-A register. Write operation starts with a valid “START” command, followed by device address byte with Read-Write bit set to “0.” On receiving a valid device address, FM3580 issues an “ACK” pulse. This is followed by register address byte (0x00h) to select the SOPR-A register. On receiving this register address byte, FM3580 issues an “ACK” pulse. This is followed by data byte to be written into the SOPR-A register. On receiving this data byte, FM3580 issues an “ACK” pulse. This is followed by a “STOP” command at which point write operation begins internally. Refer Write VID Registers diagram. SOPR-B Register Write Operation (Byte) Write sequence to SOPR-B register is same as the SOPR-A register write sequence described above except instead of 0x00h value for register address, 0x01h should be used. This will select SOPR-B register. Refer Write VID Registers diagram. |
类似零件编号 - FM3580 |
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类似说明 - FM3580 |
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