bd6758mwv ROHM Co. Ltd., bd6758mwv Datasheet - Page 24

• Manufacturer Part Number: bd6758mwv
• Description: 5ch System Lens Drivers For Digital Still Cameras 
• Manufacturer: ROHM Co. Ltd.

7)
The More Precise Constant-Current Settings (BD6370GUL)
Regarding Constant-Current Drive blocks (ch4 and ch5), there is the metal impedance of each RNF in BD6370GUL inside: 4m
(Typ.) and 22m
considered, set each D/A Converter to drive the actuator in the more precise constant current.
The more correct D/A Converter settings of Constant-Current H-bridge (ch4 and ch5)
(ex.) If there are V
Else if there are V
different to the patterning), then
Fig.47 Metal Impedance and Board Patterning Impedance of Constant-Current block
R
R
R
V
I
BD6370GUL
Constant Current Drive block (ch4 and ch5)
OUTx
Output current value; I
Output current value (ch4); I
Output current value (ch5); I
Output current value (ch4); I
Output current value (ch5); I
RNFx
METALx
Wx_1, 2
DACx
Level Shift
Level Shift
Pre Driver
6bit DAC
Pre Driver
6bit DAC
;
;
;
(Typ.), respectively. Then the metal impedances and the board patterning impedances of RNF4 and RNF5 lines
DACx
;
;
&
&
external component of output current detection
metal impedance of BD6370GUL’s inside
board patterning impedance
setting value of constant current
current flowed through the motor
=0.1[V], R
DACx
I4
5
V
V
DACI4
DAC5
=0.1[V], R
RNFx
OUTx
=0.5[ ], and R
RNFx
[A] = V
C.V./C.C./Full ON
= 0.5[ ], and R
OUT4
OUT5
OUT4
OUT5
H bridge
H bridge
C.C.
[A] = 0.1[V] (0.5[ ] 0.004[ ] 0[ ]) = 0.198
[A] = 0.1[V] (0.5[ ] 0.022[ ] 0[ ]) = 0.191
[A] = 0.1[V] (0.5[ ] 0.004[ ] 0.05[ ]) = 0.181
[A] = 0.1[V] (0.5[ ] 0.022[ ] 0.05[ ]) = 0.175
DACx
R
=4m (Typ.)
R
=22m (Typ.)
METALI4
METAL5
[V] (R
Wx_1
OUT4A
OUT4B
OUT5A
OUT5B
RNF4
RNF5
Wx_1
R
24/32
RNFx
VM
Wx_2
[ ] R
A3
A2
B1
A1
C1
D1
E1
=0[ ] (the ideal patterning condition), then
R
Wx_2
R
R
W4_1
W5_1
=0.05[ ] (the more closely real patterning condition; the value is
METALx
I
I
OUT4
OUT5
[ ] R
R
R
RNFI4
RNF5
Wx_1
R
R
[ ] R
W4_2
W5_2
Board Ground
Wx_2
[ ])