CXAC85253 is a highly integrated EL lamp driver integrated circuit that incorporates an oscillator, frequency divider, coil driver circuit, and H-bridge switch network. The chip adopts a compact TSSOP-8 package, and only one inductor and one resistor are needed to construct a complete driving system on the periphery, greatly simplifying circuit design and reducing system costs. Its ultra-low standby current of 10nA makes it an ideal choice for battery powered portable devices.
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[ CXAC85253 ]"
CXAC85253: High performance electroluminescent lamp driver chip, empowering portable device backlight systems
Today, as portable electronic devices increasingly pursue slimness and low power consumption, electroluminescent (EL) lamps have become an ideal choice for backlight displays due to their uniform emission, ultra-thin structure, and low power consumption characteristics. CXAC85253, as a DC-AC inverter driver chip designed specifically for EL lamps, can convert low-voltage DC power from 1.8V to 3.5V into AC output of up to 140Vpp. It is widely used in devices such as pagers, mobile phones, and portable players, providing efficient and reliable driving solutions for backlight systems.
Chip Overview
CXAC85253 is a highly integrated EL lamp driver integrated circuit that incorporates an oscillator, frequency divider, coil driver circuit, and H-bridge switch network. The chip adopts a compact TSSOP-8 package, and only one inductor and one resistor are needed to construct a complete driving system on the periphery, greatly simplifying circuit design and reducing system costs. Its ultra-low standby current of 10nA makes it an ideal choice for battery powered portable devices.
Core Features
1. Wide voltage input and high voltage output capability
• Input voltage range: 1.8V– 3.5VPerfectly compatible with single or dual battery power supply systems
• Typical output capability: 140Vpp AC voltageMeet the driving needs of most EL lamps
• Output adjustment range: 120– 160VppAdapt to EL light strips of different sizes and brightness
2. Ultra low power consumption design
• Typical standby current is only 10nAGreatly extend the battery life of portable devices
• Integrated Enable Control Pin (ENB)Built in 300K pull-down resistor for convenient system power management
3. High integration and simple peripherals
• Built in oscillator and frequency dividerOnly one external resistor (RT1) is needed to accurately set the oscillation frequency
• Integrated H-bridge driver networkDirectly drive EL light strips without the need for external power switches
• Integrated current limitation for coil drive(Typical 70mA, maximum 150mA), to prevent inductance saturation
4. Complete protection mechanism
• Working temperature range: -20 ° C; C to+70° CAdapt to various environmental conditions
• Built in thermal protection circuitEnsure reliable operation of the chip under harsh conditions
Detailed explanation of technical principles
Oscillators and Frequency Control
CXAC85253 adopts a precision reference voltage source (1.27V) and a current bias circuit internally, and sets the oscillation frequency through an external resistor REXT. The fundamental frequency generated by the oscillator is divided by 384 to obtain the EL lamp driving frequency, ensuring that the lamp operates at the optimal efficiency point.
Calculation formula for oscillation frequency:
EL lamp driving frequency:
Coil drive and boost principle
The chip adopts a simplified boost converter topology, which boosts the battery voltage to the high voltage required by the EL lamp through a coil driving circuit. When the internal switch is turned on, the current stores energy in the coil; When the switch is turned off, energy is transferred to the EL lamp capacitor through the internal diode. This alternating working mode achieves efficient energy conversion.
H-bridge driver network
To achieve a peak to peak voltage output of 140Vpp, the chip integrates a full H-bridge switch network internally. This network drives EL lamps with alternating polarity to ensure balanced excitation of the electrodes on both sides of the lamp, prolong the service life of the lamp, and improve luminous efficiency.
Application Design Guidelines
Selection of peripheral components
• Inductance selectionRecommended 1mH/0.15A inductance, higher inductance values can reduce peak current but require corresponding adjustment of resistance values
• filter capacitorSelect the appropriate value based on the input voltage (see Table 1 in the technical document), which requires a 70-80V withstand voltage capability
• FM resistorUsing low-temperature drift resistors to maintain frequency stability, the calculation formula is:
PCB layout suggestions
Due to the involvement of high-voltage output, PCB layout is crucial for system performance:
• The input bypass capacitor, filter capacitor, and oscillation resistor should be placed as close as possible to the chip pins
• Keep the ground path short and wide to minimize ground bounce noise
• High voltage wiring should be kept at an appropriate distance from other signal lines
Typical application scenarios
• Portable communication devicesPager, mobile phone button backlight and display backlight
• Consumer electronics productsPortable CD player, mini speaker, calculator display
• industrial equipmentInstrument and meter indication, control panel backlight
• handheld device: Data collector, portable medical device display
Summary of Electrical Characteristics
| parameter | condition | minimum | typical value | maximum | unit |
|---|---|---|---|---|---|
| power supply voltage | one point eight | - | three point five | V | |
| output voltage | 1.8V < VDD ≤ 3.5V | one hundred and twenty | one hundred and forty | one hundred and sixty | Vpp |
| standby current | VDD = 3.0V, ENB = 0 | - | ten | one hundred | nA |
| Peak current of coil | 1.8V < VDD ≤ 3.5V | seventy | - | one hundred and fifty | mA |
| clock frequency | REXT = 125KΩ | one hundred and twelve | one hundred and forty | one hundred and sixty-eight | kHz |
| EL lamp driving frequency | - | three hundred and sixty-four point six | - | Hz |
Packaging and Supply Information
CXAC85253 is packaged in TSSOP-8 and measures only 3.1mm in size; 4.5mm × 1.05mm， Pin spacing of 0.65mm, suitable for high-density PCB layout. The product is supplied in reel packaging, with 2500 pieces per reel, meeting the demand for large-scale production.
About JTM-IC Jiataimu
JTM-IC focuses on the research and sales of high-performance analog chips and power management solutions, covering multiple fields such as display drivers, power conversion, and battery management. The company adheres to technological innovation as its core, providing high reliability and high-performance semiconductor solutions to global customers.
For more technical information, reference designs, and sample applications about CXAC85253, please visit the official website:http://www.jtm-ic.com
