BA3899 Rohm, BA3899 Datasheet - Page 6
![no-image](/images/manufacturer_photos/0/5/571/rohm_sml.jpg)
BA3899
Manufacturer Part Number
BA3899
Description
EL driver for portable sets
Manufacturer
Rohm
Datasheet
1.BA3899.pdf
(8 pages)
•
(1) EL drive output
As shown in Figure 4, the EL drive output consists of
charging (rise in voltage caused by switching) and dis-
charging waveforms. The switching frequency is deter-
mined by f
by f
(2) Setting f
The oscillation frequency is determined by charging
and discharging of the external capacitance of the C1
pin. The value for C1 should be set based on the fol-
lowing equation.
The recommended setting range for f
800Hz. However, the V
determined by f
the pressure withstand values of Q1, Q2, and D1.
(3) f
f
determined by the external capacitance of the C2 pin.
This value (1500pF) is determined by the inductance
value and the Q2 transistor capability. When changing
this value, the drive capability of Q2 must be taken into
consideration in order to avoid the possibility of mal-
function.
6
SW2
Standard ICs
Operation notes
SW1
C1 =
SW2
is the switching pressure rise frequency, and is
.
= (3.14E – 6)
V
O (Max.)
SW2
V
SW1
C1
and the charging and discharging timing
SW1
(
, so caution is required concerning
1
1
I
1
+
O
f
SW1
1
1
I
2
(
Max.
Charge
)
t
1
) shown in Figure 4 is
t
SW1
(f
SW1
f
(V
SW1
)
1
CC
SW1
Discharge
= 5V)
is 40Hz to
t
2
Fig.4
(4) Q1, Q2, and D1
The V
V
mended, caution is required concerning the pressure
withstand value. Also, Q2 must have characteristics
which allow it to keep pace with the switching speed of
f
(5) R
With a configuration like that shown in Figure 5, the
volume of light can be adjusted. However, R
be set so that I
If I
and other elements can cause oscillation of the C2 pin
to stop. Be sure the above condition is satisfied.
SW2
O
, so if using any transistor other than that recom-
X
.
> 40 A, LSI dispersion, temperature fluctuation,
X
O
(resistor for adjusting light volume)
(
Max.
) shown in Figure 4 is applied to the output
1500pF
Ix ( =
X
satisfies the following condition.
C2
4
Vx – 0.2V
Rx
Fig.5
Ix
) < 40 A
Rx
Vx
BA3899F
X
should