Datasheet

Detailed Description of Hardware
The MAX4990 EV kit provides a proven layout for the
MAX4990. Component selection, adjustment range,
and typical operation values for a typical EL panel
(1.5in x 2.5in area, nominal 15nF load capacitance) are
described in the sections that follow.
Slew Rate (R
SLEW
)
Slew rate is set by the resistance on the SLEW pin (see
Table 2). Many other adjustments depend upon the
slew rate setting as a reference. The equation is:
The VR1 + R1 resistance can be adjusted to a specific
value before applying power, by connecting an ohm-
meter between JU1 pin 3 and GND. After adjusting VR1
to the desired value, disconnect the ohmmeter, install
the JU1 shunt, and finally, apply power to the EV kit.
Output Voltage (R
DIM
, R
SLEW
)
The output voltage control interacts with the slew rate
control (see Table 3). Peak-to-peak output voltage is set
by the ratio of the resistances on the DIM and SLEW pins:
The VR2 resistance can be adjusted to a specific value
before applying power, by connecting an ohmmeter
between JU3 pin 1 and GND. After adjusting VR2 to the
desired value, disconnect the ohmmeter, install the JU3
shunt, and finally, apply power to the EV kit.
V
R
R
subject to the constra V V V
PP
DIM
SLEW
PP−−
=× ≤≤200 70 250, int
Slew Rate
V
sR
M
SLEW
100
11 25
µ
⎛
⎝
⎜
⎞
⎠
⎟
= Ω
.
()
Evaluates: MAX4990
MAX4990 Evaluation Kit
_______________________________________________________________________________________ 3
JU1 SHUNT
POSITION
VR1
TRIMMER
R
SLEW
(MΩ)
SLEW RATE
(V/100µs)
1-2 — R2 = 0.374 30
25% CW
VR1 + R1 =
0.560
20
2-3
50% CW
VR1 + R1 =
0.997
12
Table 2. Slew Rate Configuration
CW = Clockwise. Approximate trimmer values provided for ini-
tial guidance only.
JU1 SHUNT
POSITION
VR1 TRIMMER
R
SLEW
(MΩ)
JU3 SHUNT
POSITION
VR2 TRIMMER
R
DIM
(MΩ)
V
P-P
(V)
2-3 — R4 = 0.374 200
7% CW VR2 = 0.152 90
13% CW VR2 = 0.272 150
1-2 — R2 = 0.374
1-2
19% CW VR2 = 0.386 200
2-3 — R4 = 0.374 144
10% CW VR2 = 0.211 80
25% CW VR2 = 0.496 182
25% CW
VR1 + R1 =
0.560
1-2
36% CW VR2 = 0.729 242
2-3 — R4 = 0.374 86
19% CW VR2 = 0.383 86
35% CW VR2 = 0.700 150
2-3
50% CW
VR1 + R1 =
0.997
1-2
70% CW VR2 = 1.398 260
Table 3. Output Voltage Configuration
CW = Clockwise. Approximate trimmer values provided for initial guidance only.