Datasheet AD7294 (Analog Devices)

12-Bit Monitor and Control System with Multichannel ADC, DACs, Temperature Sensor, and Current Sense Data Sheet AD7294 FEATURES APPLICATIONS 12-bit SAR ADC with 3 μs conversion time Cellular base stations 4 uncommitted analog inputs GSM, EDGE, UMTS, CDMA, TD-SCDMA, W-CDMA, WiMAX Differential/single-ended Point-to-multipoint and other RF transmission systems VREF, 2 × VREF input ranges 12 V, 24 V, 48 V automotive applications 2 high-side current sense inputs Industrial controls 5 V to 59.4 V operating range GENERAL DESCRIPTION 0.5% max gain error ±200 mV input range
The AD7294 contains all the functions required for general-
2 external diode temperature sensor inputs
purpose monitoring and control of current, voltage, and
−55°C to +150°C measurement range
temperature integrated into a single-chip solution. The device
±2°C accuracy
includes low voltage (±200 mV) analog input sense amplifiers
Series resistance cancellation
for current monitoring across shunt resistors, temperature sense
1 internal temperature sensor
inputs, and four uncommitted analog input channels multiplexed
±2°C accuracy
into a SAR analog-to-digital converter (ADC) with a 3 μs conver-
Built-in monitoring features
sion time. A high accuracy internal reference is provided to drive
Minimum/maximum recorder for each channel
both the digital-to-analog converter (DAC) and ADC. Four 12-bit
Programmable alert thresholds
DACs provide the outputs for voltage control. The AD7294 also
Programmable hysteresis
includes limit registers for alarm functions. The device is designed
Four 12-bit monotonic 15 V DACs
on Analog Devices, Inc., high voltage DMOS process for high
5 V span, 0 V to 10 V offset
voltage compliance, 59.4 V on the current sense inputs, and up
8 μs settling time
to a 15 V DAC output voltage.
10 mA sink and source capability
The AD7294 is a highly integrated solution that offers all the
Power-on resets (POR) to 0 V
functionality necessary for precise control of the power amplifier
Internal 2.5 V reference
in cellular base station applications. In these types of applications,
2-wire fast mode I2C interface
the DACs provide 12-bit resolution to control the bias currents
Temperature range: −40°C to +105°C
of the power transistors. Thermal diode-based temperature sensors
Package type: 64-lead TQFP or 56-lead LFCSP
are incorporated to compensate for temperature effects. The ADC monitors the high-side current and temperature. All this function- ality is provided in a 64-lead TQFP or a 56-lead LFCSP operating over a temperature range of −40°C to +105°C.
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Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY FUNCTIONAL BLOCK DIAGRAM SPECIFICATIONS DAC SPECIFICATIONS ADC SPECIFICATIONS GENERAL SPECIFICATIONS TIMING CHARACTERISTICS I2C Serial Interface Timing and Circuit Diagrams ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TERMINOLOGY DAC TERMINOLOGY ADC TERMINOLOGY THEORY OF OPERATION ADC OVERVIEW ADC TRANSFER FUNCTIONS ANALOG INPUTS Single-Ended Mode Differential Mode Driving Differential Inputs Using an Op Amp Pair Pseudo Differential Mode CURRENT SENSOR Choosing RSENSE Current Sense Filtering Kelvin Sense Resistor Connection ANALOG COMPARATOR LOOP TEMPERATURE SENSOR Remote Sensing Diode Ideality Factor Base Emitter Voltage Base Resistance hFE Variation Series Resistance Cancellation DAC OPERATION Resistor String Output Amplifier ADC AND DAC REFERENCE VDRIVE FEATURE REGISTER SETTING ADDRESS POINTER REGISTER COMMAND REGISTER (0x00) RESULT REGISTER (0x01) ADC Channel Allocation TSENSE1, TSENSE2 RESULT REGISTERS (0X02 AND 0X03) TSENSEINT RESULT REGISTER (0X04) Temperature Value Format DACA, DACB, DACC, DACD, REGISTERS (0x01 TO 0x04) ALERT STATUS REGISTER A (0x05), REGISTER B (0x06), AND REGISTER C (0x07) CHANNEL SEQUENCE REGISTER (0x08) CONFIGURATION REGISTER (0x09) Sample Delay and Bit Trial Delay POWER-DOWN REGISTER (0x0A) DATAHIGH/DATALOW REGISTERS: 0x0B, 0x0C (VIN0); 0x0E, 0x0F (VIN1); 0x11, 0x12 (VIN2); 0x14, 0x15 (VIN3) HYSTERESIS REGISTERS: 0X0D (VIN0), 0X10 (VIN1), 0X13 (VIN2), 0X16 (VIN3) TSENSE OFFSET REGISTERS (0x26 AND 0x27) I2C INTERFACE GENERAL I2C TIMING SERIAL BUS ADDRESS BYTE INTERFACE PROTOCOL Writing a Single Byte of Data to an 8-Bit Register Writing Two Bytes of Data to a 16-Bit Register Writing to Multiple Registers Reading Data from an 8-Bit Register Reading Two Bytes of Data from a 16-Bit Register MODES OF OPERATION COMMAND MODE AUTOCYCLE MODE ALERTS AND LIMITS THEORY ALERT_FLAG BIT ALERT STATUS REGISTERS DATAHIGH AND DATALOW MONITORING FEATURES HYSTERESIS Using the Limit Registers to Store Minimum/Maximum Conversion Results APPLICATIONS INFORMATION BASE STATION POWER AMPLIFIER MONITOR AND CONTROL GAIN CONTROL OF POWER AMPLIFIER LAYOUT AND CONFIGURATION POWER SUPPLY BYPASSING AND GROUNDING Layout Considerations for External Temperature Sensors OUTLINE DIMENSIONS ORDERING GUIDE