Microchip MCP4728四路电压输出数模转换方案

Microchip 公司的MCP4728是集成了EEPROM的四路12位电压输出数模转换器(DAC),它的精密的输出放大器使它能获得轨到轨的模拟输出摆幅.单电源2.7V到5.5V,采用I2C接口:地址位用户可编程于EEPROM,标准速率100 kbps,快速率400 kbps,高速率3.4Mbps,主要用于设点或失调调整,传感器校准,闭环伺服控制,低功耗手提仪表,PC外设以及工业过程控制和仪器仪表.本文介绍了MCP4728主要特性,方框图, 连接图例以及采用MCP4728的设定电或阈值校准连接图.

The MCP4728 device is a quad, 12-bit voltage output Digital-to-Analog Converter (DAC) with non-volatile memory (EEPROM). Its on-board precision output amplifier allows it to achieve rail-to-rail analog output swing.

The DAC input codes, device configuration bits, and I2C address bits are programmable to the non-volatile memory (EEPROM) by using I2C serial interface commands. The non-volatile memory feature enables the DAC device to hold the DAC input codes during power-off time, allowing the DAC outputs to be available immediately after power-up with the saved settings. This feature is very useful when the DAC device is used as a supporting device for other devices in applications network.

The MCP4728 device has a high precision internal voltage reference (VREF = 2.048V). The user can select the internal reference or external reference (VDD) for each channel individually.

Each channel can be operated in normal mode or power-down mode individually by setting the configuration register bits. In power-down mode, most of the internal circuits in the powered down channel are turned off for power-savings and the output amplifier can be configured to present a known low, medium, or high resistance output load.

The MCP4728 device includes a Power-On-Reset (POR) circuit to ensure reliable power-up and an on-board charge pump for the EEPROM programming voltage.

The MCP4728 has a two-wire I2C compatible serial interface for standard (100 kHz), fast (400 kHz), or high speed (3.4 MHz) mode.

The MCP4728 DAC is an ideal device for applications requiring design simplicity with high precision, and for applications requiring the DAC device settings to be saved during power-off time.

The MCP4728 device is available in a 10-lead MSOP package and operates from a single 2.7V to 5.5V supply voltage.

MCP4728主要特性:

• 12-Bit Voltage Output DAC with 4 Buffered Outputs

• On-Board Non-Volatile Memory (EEPROM) for DAC Codes and I2CTM Address Bits

• Internal or External Voltage Reference Selection

• Output Voltage Range:

- Using Internal VREF (2.048V):

0.000V to 2.048V with Gain Setting = 1

0.000V to 4.096V with Gain Setting = 2

- Using External VREF (VDD): 0.000V to VDD

• ±0.2 LSB DNL (typical)

• Fast Settling Time: 6 μs (typical)

• Normal or Power-Down Mode

• Low Power Consumption

• Single-Supply Operation: 2.7V to 5.5V

• I2C Interface:

- Address bits: User Programmable to EEPROM

- Standard (100 kbps), Fast (400 kbps) and High Speed (3.4 Mbps) Modes

• 10-Lead MSOP Package

• Extended Temperature Range: -40℃ to +125℃

MCP4728应用:

• Set Point or Offset Adjustment

• Sensor Calibration

• Closed-Loop Servo Control

• Low Power Portable Instrumentation

• PC Peripherals

• Programmable Voltage and Current Source

• Industrial Process Control

• Instrumentation

图1.MCP4728功能方框图

图2.MCP4728连接图例

图3.采用MCP4728的设定电或阈值校准图