MAX14521E Datasheet, PDF (20/20 Pages) Maxim Integrated Products – Quad, High-Voltage EL Lamp Driver with I2C Interface

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
section for compatible lamp sizes.
Snubber Selection
An R_SN value of 20Ω and C_SN value of 330pF is suffi-
cient for V_DD < 5V and C_{LAMP_TOTAL} < 40nF. For higher
capacitive loads on the EL output or for V_DD > 5V, C_SN
must be increased to keep LX spikes less than 30V.
f_SW Selection
Choose a boost-converter frequency such that the sat-
uration current of the tapped-inductor primary coil is
not exceeded. Special attention must be given to pro-
gram 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 accordingly to obtain the acquired wave-
shape 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 possi-
ble. Use large ground planes where possible.
Chip Information
PROCESS: BiCMOS-DMOS
Package Information
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
24 TQFN-EP
T2444M-1
21-0139
TOP VIEW
18 17 16 15 14 13
EL3 19
N.C. 20
COM 21
N.C. 22
EL2 23
N.C. 24 +
12 RB
11 SCL
MAX14521E
10 SDA
9 VDD
8 A1
*EP _{7 A0}
12 34 56
TQFN-EP
*EXPOSED PAD. CONNECT EP TO GND.
Pin Configuration
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implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
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