Rainbow-electronics MAX1718 Manual do Utilizador descarregar pdf (Página 21)

MAX1718

Notebook CPU Step-Down Controller for Intel

Mobile Voltage Positioning (IMVP

II)

______________________________________________________________________________________ 21

interval of 2

PULLUP

4.7nF is recommended

between ZMODE samples.

In some cases, it is desirable to determine the

Impedance mode code during system boot so that sev-

eral processor types can be used without hardware

modifications. Figure 14 shows one way to implement

this function. The desired code is determined by the

system BIOS and programmed into one register of the

MAX1609 using the SMBus™ serial interface. The

MAX1609’s other register is left in its power-up state (all

outputs high impedance). When SMBSUS is low, the

outputs are high impedance and do not affect the

Logic-mode VID code setting. When SMBSUS is high,

the programmed register is selected, and the MAX1609

forces a low impedance on the appropriate VID input

pins. The ZMODE signal is delayed relative to the SMB-

SUS pin because the VID pins that are pulled low by

the MAX1609 take significant time to rise when they are

released. One additional benefit of using the MAX1609

for this application is that the application uses only five of

the MAX1609’s high-voltage, open-drain outputs. The

other three outputs can be used for other purposes.

Output Voltage Transition Timing

The MAX1718 is designed to perform output voltage

transitions in a controlled manner, automatically mini-

mizing input surge currents. This feature allows the cir-

cuit designer to achieve nearly ideal transitions,

guaranteeing just-in-time arrival at the new output volt-

age level with the lowest possible peak currents for a

given output capacitance. This makes the IC ideal for

IMVP-II CPUs.

IMVP-II CPUs operate at two distinct clock frequencies

and require three distinct VID settings. When transition-

ing from one clock frequency to the other, the CPU first

goes into a low-power state, then the output voltage

and clock frequency are changed. The change must

be accomplished in 100µs or the system may halt.

MAX1718

ZMODE

ZMODE = HIGH = 1.25V

ZMODE = LOW = 1.15V

1kΩ

1kΩ100kΩ

1kΩ

100kΩ

2.7V TO 5.5V

NOTE: USE PULLUP FOR LOGIC MODE 1, PULLDOWN FOR LOGIC MODE 0.

USE ≥100kΩ FOR IMPEDANCE MODE 1, ≤1kΩ FOR IMPEDANCE MODE 0.

Figure 12. Using the Internal Mux with Both VID Codes Resistor Programmed

ZMODE SUS

OUTPUT VOLTAGE

DETERMINED BY:

GND GND Logic Level of D0–D4

GND Impedance of D0–D4

Logic Levels of S0, S1

Table 5. DAC Mux Operation

SMBus™ is a trademark of Intel Corp.

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 34 35

Comentários a estes Manuais

Sem comentários

Rainbow-electronics MAX1718 Manual do Utilizador Página 21

Comentários a estes Manuais

Manuais e produtos relacionados com Sensores Rainbow-electronics MAX1718