REV. A

–16–

ADM1028

Table X. Register 0xCO Fan Speed Ramp Register. Power-On Default <7:0> = 00h

Bit

Name

Read/Write

Description

0

Fan Speed Ramp

Read/Write

Setting this bit to a “1” will enable the fan speed ramping mechanism.

Enable

When this bit is a 1, writing to the Fan Speed Register will set the new

target fan speed; the input to the DAC will then count, up or down as

appropriate, to the new fan speed value at the rate specified in bits [1:2]

of this register. Clearing this bit to “0” will disable the fan speed ramp-

ing mechanism and will cause data written to the Fan Speed Register to

be immediately reflected to the DAC. The DAC input may or may not

continue ramping if this bit is changed from a “1” to a “0” while the fan

speed is currently ramping.

<2:1>

Ramp Rate

Read/Write

Fan Speed Ramp Rate. The speed at which the fan speed ramp counter

increments/decrements is selected as follows:

Bits <2:1>

Count Rate

Counter Frequency

00

1.0s

1 Hz

01

0.25s

4 Hz

10

0.125s

8 Hz

11

0.0625s

16 Hz

<7:3>

Reserved

Read/Write

Reserved (Default = 0)

16-Lead Shrink Small Outline Package (QSOP)

(RQ-16)

16

9

8

1

0.197 (5.00)

0.189 (4.80)

0.244 (6.20)

0.228 (5.79)

PIN 1

0.157 (3.99)

0.150 (3.81)

SEATING

PLANE

0.010 (0.25)

0.004 (0.10)

0.012 (0.30)

0.008 (0.20)

0.025

(0.64)

BSC

0.059 (1.50)

MAX

0.069 (1.75)

0.053 (1.35)

0.010 (0.20)

0.007 (0.18)

0.050 (1.27)

0.016 (0.41)

8

0

REF: JEDEC 0.150" SSOP – DRAWING NUMBER MO-137

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

Revision History

Location

Page

Data Sheet changed from REV. 0 to REV. A.

Edits to FUNCTIONAL BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Edits to SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Added Fan Speed Ramp Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Edits to Table III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Added Table X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16