MAX1717 查看數據表（PDF） - Maxim Integrated

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MAX1717

Dynamically Adjustable, Synchronous Step-Down Controller for Notebook CPUs

Maxim Integrated 

Dynamically Adjustable, Synchronous

Step-Down Controller for Notebook CPUs

This can be achieved in several ways, including the fol-

lowing two (Figure 10). By using low-impedance pull-up

resistors with the CPU’s VID pins, each pin provides the

low impedance needed for the mux to correctly inter-

pret the B-mode setting. Unfortunately, the low resis-

tances cause several mA additional quiescent current

for each of the CPU’s grounded VID pins. This quies-

cent current can be avoided by taking advantage of the

fact that D0–D4 need only appear low impedance

briefly, not necessarily on a continuous DC basis. High-

impedance pull-ups can also be used if they are

bypassed with a large enough capacitance to make

them appear low impedance for the 4µs sampling inter-

val. As noted in Figure 10, 4.7nF capacitors allow the

inputs to appear low impedance even though they are

pulled up with 1MΩ resistors.

3V TO 5.5V

A-MODE VID =

01101 → 1.35V

D4

100kΩ

D3

D2

D1

D0

B-MODE VID =

01000 → 1.60V

MAX1717

A/B

A/B = LOW = 1.60V

A/B = HIGH = 1.35V

Figure 7. Using the Internal Mux with Hard-Wired A-Mode and

B-Mode DAC Codes

3V TO 5.5V

100kΩ

+5V

VCC

MAX1717

40kΩ 40kΩ 40kΩ 40kΩ 40kΩ

D4

D3

D2

B-DATA

LATCH

D1

D0

8kΩ 8kΩ 8kΩ 8kΩ 8kΩ

GND

Figure 8. Internal Mux B-Mode Data Test and Latch

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