参数资料
| 型号： | MAX8821EVKIT+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 9/14页 |
| 文件大小： | 0K |
| 描述： | KIT EVAL FOR MAX8821 |
| 其它有关文件： | Automotive Product Guide |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 1 |
| 主要目的： | 接口，串行器，解串器（串并行转换器） |
| 已用 IC / 零件： | MAX8821 |
| 已供物品： | 板 |
MAX8821 Evaluation Kit
Detailed Description
The MAX8821 EV kit features LED display backlighting,
an audio loudspeaker amplifier, and dual LDOs for
camera functions. The MAX8821 includes soft-start,
thermal shutdown, open-circuit and short-circuit protec-
tions for the white LEDs, audio amplifier, and two LDOs.
LED Charge Pump
The MAX8821 features an inverting charge pump and
six current regulators capable of 25.6mA each to drive
six LEDs. The current regulators are matched to within
±1% (typ), providing uniform white LED brightness for
LCD backlight applications. To maximize efficiency, the
current regulators operate with as little as 0.15V voltage
drop. Individual white LED current regulators conduct
current to GND or NEG to extend usable battery life. In
the case of mismatched forward voltage of white LEDs,
only the white LEDs requiring higher voltage are
switched to direct current to NEG instead of GND, fur-
ther raising efficiency and reducing battery current
drain. The on-chip ambient temperature derating func-
tion safely allows bright 25.6mA full-scale output cur-
rent while automatically reducing current gradually
above +40°C in accordance with popular LED ratings.
Ramp-Up and Ramp-Down Function
The LED drivers in the MAX8821 provide ramp-up, and
ramp-down of LED current for smooth transitions
between different brightness settings. A controlled ramp
is used when the LED current level is changed, when
the LEDs are enabled, and when the LEDs are disabled.
The LED currents ramp up and down smoothly on a
pseudo-log scaling of the LED current sources. Each
LED source has an individual ramp control making it
possible to ramp different LEDs at different rates.
Blink Timer
The current regulators for LED5 and LED6 feature a
blink function. The OFF and ON time for LED5 and
LED6 can be set using the MAX8821 EV kit software.
Combining Blink Timer and Ramp Function
To combine the ramp function together with the blink
timer for LED5 and/or LED6, special timing considera-
tions need to be fulfilled. It is recommended to keep
the ramp-up timer shorter than the ON blink timer and
the ramp-down timer shorter than the OFF timer.
Failing to comply with these timing constraints results in
the LED_ not reaching the programmed current during
the ON time, and the I LED _ current not returning to 0mA
during the off time. Refer to the equations found in the
Combining Blink Timer and Ramp Function section of
the MAX8821 IC data sheet.
LED Short and Open-Circuit Protection
If any LED fails as an open circuit, the corresponding
LED_ is internally connected to ground and the charge
pump is enabled. To disable the corresponding current
regulator, short any unused LED_ to VBATT+. The
MAX8821 contains special circuitry to detect this con-
dition and disables the corresponding current regulator
to avoid wasting battery power.
Temperature Derating
The MAX8821 contains a derating function that auto-
matically limits the LED current at high temperatures in
accordance with the recommended derating curve of
popular white LEDs. The derating function enables the
safe usage of higher LED current at room temperature,
thus reducing the number of LEDs required to backlight
the display. The derating circuit reduces the LED cur-
rent above +40°C at approximately 1.67%/°C. The tem-
perature derating function is enabled/disabled using the
MAX8821 EV kit software and by default is disabled.
Audio Amplifier
The audio amplifier in the MAX8821 is a 2W Class D
loudspeaker amplifier. The amplifier features a pro-
grammable gain control through the MAX8821 EV kit
software and can be set from -3dB to +24dB.
The amplifier operates from a single 2.7V to 5.5V sup-
ply and features an internally generated common-mode
bias voltage of V IN3 /2 referenced to ground.
A unique filterless modulation scheme and spread-
spectrum mode create a compact, flexible, low-noise,
efficient audio power amplifier while occupying minimal
board space. The differential input architecture
reduces common-mode noise pickup with or without
the use of input-coupling capacitors. The MAX8821
audio amplifier can also be configured as a single-
ended input amplifier. The input capacitor C2 is
required for single-ended input applications.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8821EVKIT+ | 功能描述:电源管理IC开发工具 MAX8821 Eval Kit RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| MAX8822ETE+ | 功能描述:LED照明驱动器 Negative Charge Pump LED Driver RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| MAX8822ETE+T | 功能描述:LED照明驱动器 Negative Charge Pump LED Driver RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| MAX882C/D | 功能描述:低压差稳压器 - LDO RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| MAX882C/D DIE | 制造商:Maxim Integrated Products 功能描述: |
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