BU64241GWZ Datasheet, PDF (14/24 Pages) Rohm – Linear Constant Current VCM Driver

BU64241GWZ
Datasheet
・Step B3 – Controlling Step Mode
Step mode is the control period in which the lens is moved by small output current steps. During step mode it is
possible to control the step resolution and step time in order to generate just enough output current to float the lens with
minimal ringing effects. Ringing can be better controlled by choosing a large value for the step time and a small value
for the step resolution with the trade off of a greater settling time. The step time and step resolution should be chosen
depending on the acceptable system limits of ringing vs. settling time.
Step mode is used when M = 1 and the present DAC code is in between point A and point B. Typically this mode is only
used during ISRC operation between point A and B, however it is possible to move the lens to point C using only step
mode if point C is set such that point C is only 1 DAC code greater than point B.
Step mode is controlled by the 5 bit step time, stt[4:0], and 3 bit step resolution, str[2:0], values stored in register
W2W1W0 = 100b.
stt[4:0]
00000
00001
00010
00011
00100
00101
00110
00111
Step Time
-
50 µs
100 µs
150 µs
200 µs
250 µs
300 µs
350 µs
stt[4:0]
Table 2. Step Time Settings
Step Time
stt[4:0]
Step Time
01000
400 µs
10000
800 µs
01001
450 µs
10001
850 µs
01010
500 µs
10010
900 µs
01011
550 µs
10011
950 µs
01100
600 µs
10100
1000 µs
01101
650 µs
10101
1050 µs
01110
700 µs
10110
1100 µs
01111
750 µs
10111
1150 µs
stt[4:0]
11000
11001
11010
11011
11100
11101
11110
11111
Step Time
1200 µs
1250 µs
1300 µs
1350 µs
1400 µs
1450 µs
1500 µs
1550 µs
str[2:0]
000
001
Step
Resolution
-
1 LSB
Table 3. Step Resolution Settings
str[2:0]
Step
Resolution
str[2:0]
Step
Resolution
010
2 LSB
100
4 LSB
011
3 LSB
101
5 LSB
str[2:0]
110
111
Step
Resolution
6 LSB
7 LSB
www.rohm.com
© 2012 ROHM Co., Ltd. All rights reserved.
TSZ22111・15・001
14/20
TSZ02201-0H2H0B600460-1-2
01. Jul. 2013 Rev.004