HV857
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
-
-
-
205
-
-
Typ
-
20
84
240
80
88
Max
150
25
-
275
-
-
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
VA
+
_
V
REF
V
SENSE
Q
High
Voltage
Level
Translator
Q
VB
Q
V
DD
EL
Osc
REL-Osc
Figure 1: Typical Application/ Test Circuit
ON = V
DD
OFF = 0V
560kΩ
0.1µF
2.0MΩ
4
GND
1
VDD
2
RSW-Osc
3
REL-Osc
Enable Signal
2.0kΩ
VA
8
VB
7
CS
6
BAS21
LX
5
Equivalent to 3.0in
2
lamp
10nF
+
V
DD
-
HV857MG
+
V
IN
4.7µF
220µH*
3.3nF,
100V
-
* Murata Inductor
LQH32CN221K21
3
SUPERTEX [ Supertex, Inc ]
