Datasheet ADL5906 (Analog Devices) - 8

link to page 20 link to page 19 link to page 21 link to page 21 link to page 19 link to page 19 link to page 19 link to page 17 link to page 17 link to page 19 link to page 17
ADL5906 Data Sheet PIN CONFIGURATION AND FUNCTION DESCRIPTIONS N–I N+I IC IC N RF RF N 6 5 4 3 1 1 1 1 PIN 1 TADJ/PWDN 1 INDICATOR 12 VTGT NIC 2 11 VREF ADL5906 VPOS1 3 10 VPOS2 TOP VIEW GND1 4 (Not to Scale) 9 GND2 5 6 7 8 S MS EMP CRM VR VSET T V NOTES 1. NIC = NO INTERNAL CONNECTION. DO NOT CONNECT TO THIS PIN. 2. THE EXPOSED PAD REQUIRES A GOOD THERMAL
002
AND ELECTRICAL CONNECTION TO THE GROUND OF THE PRINTED CIRCUIT BOARD (PCB).
1287- 1 Figure 2. Pin Configuration
Table 3. Pin Function Descriptions Pin No. Mnemonic Description
1 TADJ/PWDN Temperature Compensation/Shutdown. This is a dual function pin used for controlling temperature slope compensation at voltages <1.0 V and/or for shutting down the device at voltages >1.4 V. The temperature compensation voltage is generally set by connecting this pin to VREF through a resistive voltage divider (see the Setting VTADJ section for additional information). See Figure 46 for an equivalent circuit. 2, 13, 16 NIC No Internal Connection. Do not connect to these pins. These pins are not internally connected. 3, 10 VPOS1, Power Supply. Because these pins are internally shorted, they must be connected to the same 5 V power VPOS2 supply. The power supply to each pin must also be decoupled using 100 pF and 100 nF capacitors located as close as possible to the pins. 4, 9 GND1, GND2 Ground. Connect both GND1 and GND2 to system ground using a low impedance path. 5 CRMS RMS Averaging Capacitor. Connect an rms averaging capacitor between CRMS and ground. See the Choosing a Value for CRMS section for more information. See Figure 48 for an equivalent circuit. 6 VRMS RMS Output. In measurement mode, this pin is connected to VSET either directly or through a resistor divider (when the slope is being increased). In controller mode, this pin is used to drive the gain control input of a voltage variable attenuator (VVA) or variable gain amplifier (VGA). See Figure 48 for an equivalent circuit. 7 VSET Setpoint Input. In measurement mode, this pin is connected to VRMS either directly or through a resistor divider. In controller mode, the voltage applied to this pin sets the decibel value of the required RF input level to balance the automatic power control loop. See Figure 47 for an equivalent circuit. 8 VTEMP Temperature Sensor Output of 1.4 V at 25°C with a Coefficient of 4.8 mV/°C. See Figure 43 for an equivalent circuit. 11 VREF Reference Voltage Output. This voltage reference has a nominal value of 2.3 V. This reference output voltage can be used to set the voltage to the TADJ/PWDN and VTGT pins. See Figure 44 for an equivalent circuit. 12 VTGT RMS Target Voltage. The voltage applied to this pin sets the target RF input at the output of the VGA that is also the rms squaring circuit. The recommended voltage for VTGT is 0.8 V. Increasing VTGT above 0.8 V degrades the rms accuracy of the ADL5906. Reducing VTGT below 0.8 V can improve the rms accuracy for signals with very high crest factors; however, it reduces the detection range of the ADL5906. See Figure 49 for an equivalent circuit. 14, 15 RFIN+, RFIN− RF Inputs. The RF inputs are normally applied single-ended with the RF input signal ac-coupled to RFIN+ and RFIN− ac-coupled to ground. See Figure 42 for an equivalent circuit. EPAD The exposed pad on the underside of the device (EPAD) is also internally connected to ground and requires a good thermal and electrical connection to the ground of the printed circuit board (PCB). Rev. A | Page 8 of 32 Document Outline Features Applications Functional Block Diagram General Description Table of Contents Revision History Specifications Absolute Maximum Ratings ESD Caution Pin Configuration and Function Descriptions Typical Performance Characteristics Theory of Operation Square Law Detector and Amplitude Target RF Input Interface Temperature Sensor Interface VREF Interface Temperature Compensation Interface Power-Down Interface VSET Interface Output Interface VTGT Interface Basis for Error Calculations Measurement Mode Basic Connections Setting VTADJ Setting VTGT Choosing a Value for CRMS Output Voltage Scaling System Calibration and Error Calculation Using VTEMP to Improve Intercept Temperature Drift Description of Characterization Evaluation Board Evaluation Board Assembly Drawings Outline Dimensions Ordering Guide