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MAX1386
Dual RF LDMOS Bias Controllers with I²C/SPI Interface
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The MAX1385/MAX1386 set and control bias conditions for dual RF LDMOS power devices found in cellular base stations. Each device includes a high-side current-sense amplifier with programmable gains of 2, 10, and 25 to monitor LDMOS drain current over the 20mA to 5A range. Two external diode-connected transistors monitor LDMOS temperatures while an internal temperature sensor measures the local die temperature of the MAX1385/MAX1386. A 12-bit ADC converts the programmable- gain amplifier (PGA) outputs, external/internal temperature readings, and two auxiliary inputs.
The two gate-drive channels, each consisting of 8-bit coarse and 10-bit fine DACs and a gate-drive amplifier, generate a positive gate voltage to bias the LDMOS devices. The MAX1385 includes a gate-drive amplifier with a gain of 2 and the MAX1386 gate-drive amplifier provides a gain of 4. The 8-bit coarse and 10-bit fine DACs allow up to 18 bits of resolution. The MAX1385/MAX1386 include autocalibration features to minimize error over time, temperature, and supply voltage.
The MAX1385/MAX1386 feature an I²C/SPI™-compatible serial interface. Both devices operate from a 4.75V to 5.25V analog supply (3.2mA supply current), a 2.7V to 5.25V digital supply (3.1mA supply current), and a 4.75V to 11.0V gate-drive supply (4.5mA supply current). The MAX1385/MAX1386 are available in a 48-pin thin QFN package.
The two gate-drive channels, each consisting of 8-bit coarse and 10-bit fine DACs and a gate-drive amplifier, generate a positive gate voltage to bias the LDMOS devices. The MAX1385 includes a gate-drive amplifier with a gain of 2 and the MAX1386 gate-drive amplifier provides a gain of 4. The 8-bit coarse and 10-bit fine DACs allow up to 18 bits of resolution. The MAX1385/MAX1386 include autocalibration features to minimize error over time, temperature, and supply voltage.
The MAX1385/MAX1386 feature an I²C/SPI™-compatible serial interface. Both devices operate from a 4.75V to 5.25V analog supply (3.2mA supply current), a 2.7V to 5.25V digital supply (3.1mA supply current), and a 4.75V to 11.0V gate-drive supply (4.5mA supply current). The MAX1385/MAX1386 are available in a 48-pin thin QFN package.
Key Features
- Integrated High-Side Drain Current-Sense PGA with Gain of 2, 10, or 25
- ±0.5% Accuracy for Sense Voltage Between 75mV and 250mV
- Full-Scale Sense Voltage of 100mV with Gain of 25
- Full-Scale Sense Voltage of 250mV with Gain of 10
- Common-Mode Range of 5V to 30V Drain Voltage for LDMOS
- Adjustable Low Noise 0 to 5V, 0 to 10V Output Gate-Bias Voltage Ranges with ±10mA Gate Drive
- Fast Clamp to 0V for LDMOS Protection
- 8-Bit DAC Control of Gate-Bias Voltage
- 10-Bit DAC Control of Gate-Bias Offset with Temperature
- Internal Die Temperature Measurement
- External Temperature Measurement by Diode-Connected Transistor (2N3904)
- Internal 12-Bit ADC Measurement of Temperature, Current, and Voltages
- Selectable I²C-/SPI-Compatible Serial Interface
- 400kHz/1.7MHz/3.4MHz I²C-Compatible Control for Settings and Data Measurement
- 16MHz SPI-Compatible Control for Settings and Data Measurement
- Internal 2.5V Reference
- Three Address Inputs to Control Eight Devices in I²C Mode
Applications/Uses
- Industrial Process Control
- RF LDMOS Bias-Control in Cellular Base Stations
Technical Docs
| Data Sheet | Dual RF LDMOS Bias Controllers with I²C/SPI Interface | Feb 25, 2009 | |
| Tutorial | General Layout Guidelines for RF and Mixed-Signal PCBs | ||
| App Note | Implementing a MAX1385-Based Control Loop in C/C++ |
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Parameters
Key Features
- Integrated High-Side Drain Current-Sense PGA with Gain of 2, 10, or 25
- ±0.5% Accuracy for Sense Voltage Between 75mV and 250mV
- Full-Scale Sense Voltage of 100mV with Gain of 25
- Full-Scale Sense Voltage of 250mV with Gain of 10
- Common-Mode Range of 5V to 30V Drain Voltage for LDMOS
- Adjustable Low Noise 0 to 5V, 0 to 10V Output Gate-Bias Voltage Ranges with ±10mA Gate Drive
- Fast Clamp to 0V for LDMOS Protection
- 8-Bit DAC Control of Gate-Bias Voltage
- 10-Bit DAC Control of Gate-Bias Offset with Temperature
- Internal Die Temperature Measurement
- External Temperature Measurement by Diode-Connected Transistor (2N3904)
- Internal 12-Bit ADC Measurement of Temperature, Current, and Voltages
- Selectable I²C-/SPI-Compatible Serial Interface
- 400kHz/1.7MHz/3.4MHz I²C-Compatible Control for Settings and Data Measurement
- 16MHz SPI-Compatible Control for Settings and Data Measurement
- Internal 2.5V Reference
- Three Address Inputs to Control Eight Devices in I²C Mode
Applications/Uses
- Industrial Process Control
- RF LDMOS Bias-Control in Cellular Base Stations
Description
The MAX1385/MAX1386 set and control bias conditions for dual RF LDMOS power devices found in cellular base stations. Each device includes a high-side current-sense amplifier with programmable gains of 2, 10, and 25 to monitor LDMOS drain current over the 20mA to 5A range. Two external diode-connected transistors monitor LDMOS temperatures while an internal temperature sensor measures the local die temperature of the MAX1385/MAX1386. A 12-bit ADC converts the programmable- gain amplifier (PGA) outputs, external/internal temperature readings, and two auxiliary inputs.
The two gate-drive channels, each consisting of 8-bit coarse and 10-bit fine DACs and a gate-drive amplifier, generate a positive gate voltage to bias the LDMOS devices. The MAX1385 includes a gate-drive amplifier with a gain of 2 and the MAX1386 gate-drive amplifier provides a gain of 4. The 8-bit coarse and 10-bit fine DACs allow up to 18 bits of resolution. The MAX1385/MAX1386 include autocalibration features to minimize error over time, temperature, and supply voltage.
The MAX1385/MAX1386 feature an I²C/SPI™-compatible serial interface. Both devices operate from a 4.75V to 5.25V analog supply (3.2mA supply current), a 2.7V to 5.25V digital supply (3.1mA supply current), and a 4.75V to 11.0V gate-drive supply (4.5mA supply current). The MAX1385/MAX1386 are available in a 48-pin thin QFN package.
The two gate-drive channels, each consisting of 8-bit coarse and 10-bit fine DACs and a gate-drive amplifier, generate a positive gate voltage to bias the LDMOS devices. The MAX1385 includes a gate-drive amplifier with a gain of 2 and the MAX1386 gate-drive amplifier provides a gain of 4. The 8-bit coarse and 10-bit fine DACs allow up to 18 bits of resolution. The MAX1385/MAX1386 include autocalibration features to minimize error over time, temperature, and supply voltage.
The MAX1385/MAX1386 feature an I²C/SPI™-compatible serial interface. Both devices operate from a 4.75V to 5.25V analog supply (3.2mA supply current), a 2.7V to 5.25V digital supply (3.1mA supply current), and a 4.75V to 11.0V gate-drive supply (4.5mA supply current). The MAX1385/MAX1386 are available in a 48-pin thin QFN package.
Technical Docs
| Data Sheet | Dual RF LDMOS Bias Controllers with I²C/SPI Interface | Feb 25, 2009 | |
| Tutorial | General Layout Guidelines for RF and Mixed-Signal PCBs | ||
| App Note | Implementing a MAX1385-Based Control Loop in C/C++ |
Support & Training
Search our knowledge base for answers to your technical questions.
Filtered SearchOur dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal
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