IMP522 IMP Inc, IMP522 Datasheet - Page 4

• Manufacturer Part Number: IMP522
• Description: Dual EL Lamp Driver
• Manufacturer: IMP Inc

EL Lamp Drive
The outputs V
driven by the EL oscillator. Each output is switched between C
and ground on alternate phases, creating peak-to-peak signals
across the EL lamps of twice the regulated voltage.
EL Lamp Selection: LMPSEL
The digital input pin LMPSEL allows either or both EL lamps to
be active. Lamp A is active when LMPSEL is LOW and lamp B is
active when LMPSEL is HIGH. When LMPSEL is left floating or
driven by a three-state driver in the high impedance state, both
lamp driver outputs are active.
The logic HIGH signal level is defined as greater than 0.7V
logic LOW is defined as less than 0.3V
ognized with the signal level between 0.3V
when the output impedance of the driving voltage signal source
is infinite (driver in OFF state).
Both drivers are OFF if the IMP522 is disabled.
4
Application Information
H
I M P 5 2 2
I M P 5 2 2
g i
L
h
F
M
S
o l
I H
I
L
g i
m
P
O
t a
G
p
n
S
W
n i
e
H
l a
E
d
/ g
a
A
L
n
– V
c
e
AB
and V
a L
V
m
A
B
p
n a V
– V
O
O
O
A
F
d
N
N
F
AB
D
A
are configured as H-bridges,
i r
B
e v
DD
. A floating level is rec-
a L
DD
V
m
B
and 0.7V
p
n a V
O
O
O
B
408-432-9100/www.impweb.com
F
N
N
d
F
D
A
i r
5
DD
B
2
DD
e v
2
_
0 t
2
and
, or
e .
p
s
S
EL Driver Output Overvoltage Regulator
The IMP522 maximum V
120V. The internal overvoltage regulator skips the inductor
switching whenever the voltage on the C
tion threshold. The internal overvoltage detection trip point has a
hysterisis of 1V and a range of 110V to 120V at room temperature.
PWM Circuit Switching
The switching MOSFET is driven by the PWM signal (nominally
61kHz). During the first 88% of the period, the switch is ON,
providing a low impedance path (<8Ω) from L
causes the external inductor to charge. In the last 12% of the
period, the MOSFET is turned OFF. This causes the voltage on
the output of L
forward-bias the external diode, thus pumping charge into the
storage capacitor C
between 110V and 120V. When the internal regulation trip-point is
reached, the overvoltage regulator turns the MOSFET switch OFF
to conserve power.
X
to rise up to a high value. At some point, this will
S
. The voltage on C
CS
output voltage is between 110V and
S
S
increases each cycle to
pin exceeds the regula-
X
to ground. This
© 2001 IMP, Inc.