Maxim MAX11008 RF LDMOS功率管偏压控制方案

Maxim 公司的MAX11008是 RF LDMOS功率器件的偏压控制器,主要用在蜂窝基站和其它无线基础设备.每个控制器包括可编程增益2,10和25的高边电流检测放大器,用来监视LDMOS漏极电流(电流范围20mA到5A).片内集成了用来存储器LDMOS偏压特性的4Kb EEPROM,电压检测精度在±0.75%,12位DAC用来控制栅极温度和片内温度测量.本文介绍了MAX11008的主要特性,功能方框图以及采用I2C接口和SPI接口的典型应用电路.

The MAX11008 controller biases RF LDMOS power devices found in cellular base stations and other wireless infrastructure equipment. Each controller includes a high-side current-sense amplifier with programmable gains of 2, 10, and 25 to monitor the LDMOS drain current over a range of 20mA to 5A. The MAX11008 supports up to two external diode-connected transistors to monitor the LDMOS temperatures while an internal temperature sensor measures the local die temperature. A 12-bit  successive-approximation register (SAR) analogto-digital converter (ADC) converts the analog signals from the programmable-gain amplifiers (PGAs), external temperature sensors, internal temperature measurement, and two additional auxiliary inputs. The
MAX11008 automatically adjusts the LDMOS bias voltages by applying temperature, AIN, and/or drain current samples to data stored in lookup tables (LUTs).

The MAX11008 includes two gate-drive channels, each consisting of a 12-bit DAC to generate the positive gate voltage for biasing the LDMOS devices. Each gatedrive output supplies up to ±2mA of gate current. The gate-drive amplifier is current-limited to ±25mA and features a fast clamp to AGND.

The MAX11008 contains 4Kb of on-chip, nonvolatile EEPROM organized as 256 bits x 16 bits to store LUTs and register information. The device operates from either a 4-wire 16MHz SPI-/MICROWIRE-compatible or an I2C-compatible serial interface.

The MAX11008 operates from a +4.75V to +5.25V analog supply with a typical supply current of 2mA, and a +2.7V to +5.25V digital supply with a typical supply of 3mA. The device is packaged in a 48-pin, 7mm x 7mm, thin QFN package and operates over the extended (-40°C to +85°C) temperature range.

MAX11008主要特性:
On-Chip 4Kb EEPROM for Storing LDMOS Bias Characteristics
Integrated High-Side Current-Sense PGA with Gain of 2, 10, or 25
±0.75% Accuracy for Sense Voltage Between +75mV and +1250mV
Full-Scale Sense Voltage
+100mV with a Gain of 25
+250mV with a Gain of 10
+1250mV with a Gain of 2
Common-Mode Range, LDMOS Drain Voltage : +5V to +32V
Adjustable Low-Noise 0 to AVDD Output Gate Bias Voltage Range
Fast Clamp to AGND for LDMOS Protection
12-Bit DAC Control of Gate with Temperature
Internal Die Temperature Measurement
2-Channel External Temperature Measurement through Remote Diodes
Internal 12-Bit ADC Measurement for Temperature, Current, and Voltage Monitoring
User-Selectable Serial Interface 400kHz/1.7MHz/3.4MHz I2C-Compatible Interface
16MHz SPI-/MICROWIRE-Compatible Interface

MAX11008应用:
Cellular Base Stations
Microwave Radio Links
Feed-Forward Power Amps
Transmitters
Industrial Process Control



图1.MAX11008功能方框图



图2.MAX11008典型应用电路—I2C 接口



图3.MAX11008典型应用电路—SPI 接口