HV857L(2013) Ver la hoja de datos (PDF) - Supertex Inc
Número de pieza
componentes Descripción
Fabricante
HV857L Datasheet PDF : 8 Pages
| |||
Typical Waveform on VA, VB and Differential Waveform VA - VB
HV857L
Fig. 2: Split Supply and Enable/Disable Configuration
ON = VDD
OFF = 0V
Regulated Voltage = VDD
Battery Voltage = VIN
Enable Signal
CDD
RSW
REL
CIN
1
8
VDD
VA
2
HV857L
7
RSW-Osc
VB
3
REL-Osc
6
CS
4
GND
5
LX
D
LX
EL Lamp
CS
Split Supply Configuration
The HV857L can also be used for handheld devices operat-
ing from a battery where a regulated voltage is available.
This is shown in Fig. 2. The regulated voltage can be used
to run the internal logic of the HV857L. The amount of cur-
rent necessary to run the internal logic is 150µA maximum at
a VDD of 5.0V. Therefore, the regulated voltage could easily
provide the current without being loaded down.
Enable/Disable Configuration
The HV857L can be easily enabled and disabled via a logic
control signal on the RSW and REL resistors as shown in Fig.
2 below. The control signal, which can be from a micropro-
cessor, has to track the VDD supply. RSW and REL are typi-
cally very high values. Therefore, only 10’s of 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.
Audible Noise Reduction
The EL lamp, when lit, emits an audible noise. This is due to
EL lamp construction and it creates a major problem for ap-
plications where the EL lamp can be close to the ear such as
cellular phones. The HV857L employs a circuit designed to
help minimize the EL lamp’s audible noise by slowing down
the rise and fall times seen by the EL lamp.
Doc.# DSFP-HV857L
A062013
Supertex inc.
5
www.supertex.com
Share Link: 