HV857L
Electrical Characteristics (cont.)
Symbol
I
DD
I
IN
V
CS
f
EL
f
SW
D
Parameter
Input current going into the VDD pin
Input current including inductor current
Output voltage on VCS
EL lamp frequency
Switching transistor frequency
Switching transistor duty cycle
Min
-
-
-
175
65
-
Typ
-
25
92
205
77
88
Max
150
40
-
235
89
-
Units
µA
mA
V
Hz
kHz
%
Conditions
V
DD
= 1.8V to 5.0V. See Figure 1
See Figure 1*
See Figure 1
See Figure 1
See Figure 1
See Figure 1
* The inductor used is a 220µH Murata inductor, max DC resistance of 8.4Ω, part # LQH32CN221K21.
Block Diagram
LX
VDD
CS
RSW-Osc
Switch
Osc
Q
GND
+
Disable
C
_
V
REF
V
SENSE
High
Voltage
Level
Trans-
lators
Q
VA
V
DD
EL
Osc
Q
REL-Osc
VB
Q
Figure 1: Typical Application/ Test Circuit
ON = V
DD
OFF = 0V
3.0in
2
EL lamp
1
2
3
Enable Signal
+
V
DD
560kΩ
0.1µF
VDD
RSW-Osc
REL-Osc
VA
8
VB
7
CS
6
BAS21
LX
5
-
2.0MΩ
4
GND
+
V
IN
HV857LMG
4.7µF
220µH*
3.3nF,
100V
-
* Murata Inductor
LQH32CN221K21
3
SUPERTEX [ Supertex, Inc ]
