19-4456; Rev 0; 2/09
www.DataSheet4EUV.cAAoLVmUAAILTAIOBNLEKIT
Dual RF LDMOS Bias Controllers
with I2C/SPI Interface
General 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 cur-
rent-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 temper-
ature sensor measures the local die temperature of the
MAX1385/MAX1386. A 12-bit ADC converts the pro-
grammable-gain amplifier (PGA) outputs, external/inter-
nal 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.
Applications
RF LDMOS Bias Control in Cellular Base Stations
Industrial Process Control
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
Ordering Information/Selector Guide
PART
TEMP RANGE
MAX1385AETM+**
-40°C to +85°C
MAX1385BETM+
-40°C to +85°C
MAX1386AETM+**
-40°C to +85°C
MAX1386BETM+**
-40°C to +85°C
*EP = Exposed pad.
**Future product—contact factory for availability.
+Denotes a lead(Pb)-free/RoHS-compliant package.
PIN-PACKAGE
48 Thin QFN-EP*
48 Thin QFN-EP*
48 Thin QFN-EP*
48 Thin QFN-EP*
TEMP ERROR (°C)
±1
±2
±1
±2
VGATE (V)
5
5
10
10
Pin Configuration and Typical Operating Circuit (I2C Mode)
appear at end of data sheet.
SPI is a trademark of Motorola, Inc.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
