ADM8845: Charge Pump Driver for 6 White LED LCD Backlights
The ADM8845 provides the power required to drive up to 6 white LEDs from a 2.6 V to 5.5 V (li-ion) input supply, using charge pump technology. The white LEDs are used for backlighting a color LCD display. To maximize power efficiency, a charge pump that can operate in either of a 1x, 1.5x or 2x mode is used. The Charge Pump automatically switches between 1x/1.5x/2x modes based on the input voltage, to maintain correct output levels at a high power efficiency.
Improved brightness matching of the white LEDs is achieved by the use of a feedback pin to sense each individual LED current with a maximum matching accuracy of 1% and ISET to ILED maximum matching of 1%.
The ADM8845 provides two digital input control pins, CTRL1 and CTRL2, which control the shutdown operation and the brightness of the LEDs. The LEDs are arranged into two groups, main and sub display options, the main display refers to 4 of the 6 LEDs (FB1 -FB4) and the sub display refers to the remaining 2 LEDs (FB5 - FB6). Brightness control of the white LEDs can be achieved with a digital PWM signal applied to CTRL1 and/or CTRL2 to provide brightness control on the main and/or sub displays. The duty cycle of the applied digital PWM signal determines the brightness of the backlight white LEDs. Also brightness control of the white LEDs can be controlled using a DC voltage or a PWM signal applied to the ISET pin with a few external components added.
The ADM8845 also has soft-start circuitry to limit inrush current flow at power up.
The ADM8845 is fabricated using CMOS technology for minimal power consumption. The part is packaged in a 16-pin LFCSP package.
ADM8845 特点
- Drives 6 White LEDs from a 2.6 V to 5.5 V (li-ion) Input Supply
- 1x/1.5x/2x Fractional Charge Pump to Maximise Power Efficiency
- 1% LED Current Matching (Max Error)
- Up to 88% Power Efficiency
- Powers Main and Sub Displays LEDs
- Package Footprint only 9mm2 (3mm x 3mm)
- Package Height only 0.9mm
- Low Power Shutdown Mode
- Shutdown Function
- Soft-start limiting inrush current
ADM8845 功能框图
| 产品型号 | 产品状态 | 封装 | 引脚 | 温度范围 |
|---|---|---|---|---|
| ADM8845ACP-REEL | 量产 | 16 ld LFCSP (3x3mm, 1.3mm exposed pad) | 16 | 工业 |
| ADM8845ACP-REEL7 | 量产 | 16 ld LFCSP (3x3mm, 1.3mm exposed pad) | 16 | 工业 |
| ADM8845ACPZ-REEL | 量产 | 16 ld LFCSP (3x3mm, 1.3mm exposed pad) | 16 | 工业 |
| ADM8845ACPZ-REEL7 | 量产 | 16 ld LFCSP (3x3mm, 1.3mm exposed pad) | 16 | 工业 |
| ADM8845EB-EVALZ | 量产 | 评估板 | - | 待定 |