MAX14521E_15 Datasheet, PDF (20/21 Pages) Maxim Integrated Products – Quad, High-Voltage EL Lamp Driver with I2C Interface

MAX14521E
Quad, High-Voltage EL Lamp Driver
with I²C Interface
C_CS Capacitor Selection
C_CS is the output of the boost converter and provides the
high-voltage source for the EL lamp. Connect a 3.3nF
capacitor from CS to GND and place as close to the CS
input as possible.
Diode Selection
Connect a diode, D1, from the LX node to CS to rectify the
boost voltage on CS. The diode should be a fast recovery
diode that is tolerant to +200V.
EL Lamp Selection
EL lamps have a capacitance of approximately 2.5nF to
3.5nF per square inch. See the Total Input Current vs.
Load graph in the Typical Operating Characteristics sec-
tion for compatible lamp sizes.
Snubber Selection
An RSN value of 20Ω and CSN value of 330pF is suf-
ficient for V_DD < 5V and CLAMP_TOTAL < 40nF. For
higher capacitive loads on the EL output or for V_DD > 5V,
CSN must be increased to keep LX spikes less than 30V.
f_SW Selection
Choose a boost-converter frequency such that the satu-
ration current of the tapped-inductor primary coil is not
exceeded. Special attention must be given to program the
FSW bits properly when V_BAT > 5.5V to avoid destruction
of the device. In general, it is good practice to start from
the highest f_SW setting (1.6MHz) and decrease accord-
ingly to obtain the acquired waveshape on the EL outputs
and to prevent exceeding the saturation current of the
tapped-inductor.
Applications Information
PCB Layout
Keep PCB traces as short as possible. Ensure that
bypass capacitors are as close to the device as possible.
Use large ground planes where possible.
Chip Information
PROCESS: BiCMOS-DMOS
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.com/packages. Note
that a “+”, “#”, or “-” in the package code indicates RoHS status
only. Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
24 TQFN-EP
T2444M-1
21-0139
Pin Configuration
TOP VIEW
18 17 16 15 14 13
EL3 19
N.C. 20
COM 21
N.C. 22
EL2 23
N.C. 24
MAX14521E
+
*EP
12 RB
11 SCL
10 SDA
9 VDD
8 A1
7 A0
12 34 56
TQFN-EP
*EXPOSED PAD. CONNECT EP TO GND.
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