Datasheet AD8214 (Analog Devices) - 10

AD8214 Data Sheet THEORY OF OPERATION
The AD8214 is a high voltage comparator offering an input-to- connects to a voltage divider across the regulator, so the output response time of less than 100 ns. This device is ideal for comparator trips as the voltage across the series resistor crosses detecting overcurrent conditions on the high side of the control the user-selected threshold. loop. The AD8214 is designed specifically to facilitate and allow The AD8214 features a current output. The current is low (100 nA for fast shutdown of the control loop, preventing damage due to typical), until the user selected threshold is crossed. After this point excessive currents to the FET, load, or shunt resistor. the output switches to high (1 mA typical). The current output The AD8214 operates with a supply of 5 V to 65 V. It combines driver complies with load voltage from 0 V to (VS – 2.4 V). The a fast comparator, optimized for high side operation, with a current easily drives a ground referenced resistor to develop logic 2.4 V series voltage regulator. The regulator provides a stable levels determined by the value of the load resistor. voltage that is negative with respect to the positive supply rail, The comparator input is balanced to switch as the inverting and it is intended to provide power to the internal electronics, input (–IN) is driven negative with respect to the noninverting set a comparison threshold below the supply rail, and power input (+IN). As the comparator output switches from 0 mA to small application circuits used with the comparator. 1 mA, a small hysteresis (10 mV) is activated to minimize the The differential input of the comparator may be operated at, or effects of noise in the system that may be triggered by the slightly above or below, the positive supply rail. Typically, one of comparator signal. This means that to restore the output to zero, the comparator inputs is driven negative with respect to the the input polarity must be reversed by 10 mV beyond the positive supply by a small series resistor carrying the main original threshold. supply current to the load. The other input of the comparator
BATTERY CONSTANT THRESHOLD I 1 1 + R1 _ 2 + 5 SHUNT UP TO 65V _ 8 CONSTANT VOLTAGE DROP 2.4V 2.4V ACROSS SHUNT R2 REGULATOR CORRESPONDING TO CURRENT LEVEL TO LOAD 3 2 6
005
3
06193- Figure 28. Simplified Schematic Rev. A | Page 10 of 16 Document Outline Features Applications Functional Block Diagram General Description Revision History Specifications Absolute Maximum Ratings ESD Caution Pin Configuration and Function Descriptions Typical Performance Characteristics Theory of Operation Comparator Offset and Hysteresis Setting the Input Threshold Voltage Input-Referred Dynamic Error Applications Typical Setup and Calculations High Side Overcurrent Detection Outline Dimensions Ordering Guide Automotive Products