HV857MG Supertex, HV857MG Datasheet - Page 6

• Manufacturer Part Number: HV857MG
• Description: Display Drivers HVCMOS
• Manufacturer: Supertex

Specifications of HV857MG

• Driver Type: EL Lamp Drivers
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: MSOP-8
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Split Supply Configuration
The HV857 can also be used for handheld devices operating
from a battery where a regulated voltage is available. This
is shown in Figure 2. The regulated voltage can be used to
run the internal logic of the HV857. The amount of current
necessary to run the internal logic is 150µA Max at a V
3.0V. Therefore, the regulated voltage could easily provide
the current without being loaded down.
Figure 2: Split Supply and Enable/Disable Configuration
Audible Noise Reduction
This section describes a method (patented) developed at
Supertex to reduce the audible noise emitted by the EL
lamps used in application sensitive to audible noise. Figure
Figure 3: Typical Application Circuit for Audible Noise Reduction
Regulated Voltage = V
ON = V
OFF = 0V
ON = V
OFF = 0V
DD
V
DD
+
-
DD
V
V
IN
IN
+
-
DD
+
-
Enable
C
C
DD
DD
Enable Signal
C
●
IN
1235 Bordeaux Drive, Sunnyvale, CA 94089
C
IN
R
R
R
SW
R
EL
SW
EL
1
2
3
4
1
2
3
4
GND
GND
VDD
RSW-Osc VB
REL-Osc
RSW-Osc VB
REL-Osc
DD
VDD
HV857
HV857
of
6
Enable/Disable Configuration
The HV857 can be easily enabled and disabled via a logic
control signal on the R
ure 2 below. The control signal can be from a microproces-
sor. The control signal has to track the V
R
microamperes will be drawn from the logic signal when it
is at a logic high (enable) state. When the microprocessor
signal is high the device is enabled, and when the signal is
low, it is disabled.
3 shows a general circuit schematic that uses the resistor,
R
EL
SER
VA
LX
VA
LX
CS
CS
are typically very high values. Therefore, only 10’s of
, connected in series with the EL lamp.
8
7
6
5
8
7
6
5
L
X
●
Tel: [phone]
D
R
SER
L
X
D
SW
C
C
EL Lamp
S
S
and R
●
www.supertex.com
EL
resistors as shown in Fig-
EL Lamp
DD
supply. R
HV857
SW
and