Datasheet BD14220G-C (Rohm) - 9

BD1422xG-C Series Application Example
This IC has the structure specialized for Current Sense Amplifier and has the following features. Common mode voltage range is maximum 40 V with VDD of maximum 5.5 V, therefore it is possible to detect the current flowing in a power supply line exceeding VDD voltage. And its input bias current is very low. This IC amplifies the voltage difference across the shunt resistor between VINP and VINM and outputs a voltage with the REF pin as reference voltage. If the current flows from VINP to VINM, OUT pin voltage is higher than REF pin voltage. If the current flows from VINM to VINP, OUT pin voltage is lower than REF pin voltage. When the voltages of VINP and VINM are equal, OUT pin voltage is equal to REF pin voltage. Figure 9. Basic Explanation VOUT is calculated by the below formula. 𝑉𝑂𝑈𝑇 = (𝑅𝑆𝐻𝑈𝑁𝑇 × 𝐼𝐿𝑂𝐴𝐷 × 𝐺𝐴𝐼𝑁) + 𝑉𝑅𝐸𝐹 Where, 𝑅𝑆𝐻𝑈𝑁𝑇 is the Shunt resistance 𝐼𝐿𝑂𝐴𝐷 is the Load current 𝐺𝐴𝐼𝑁 is the Gain of Current Sense Amplifier 𝑉𝑅𝐸𝐹 is the REF pin voltage Also, VOUT needs to be GND < VOUT < VDD. VOUT is clipped to Low-level Output Voltage (VOUT_L) when it’s under GND. VOUT is clipped to High-level Output Voltage (VOUT_H) when it’s over VDD. To accurately sense the current through the shunt resistor, a 4-terminal Kelvin connection must be used to avoid errors in the impedance of the current path. For stability, dispose and connect a bypass capacitor for removing power source noise close to IC. Selection of shunt resistor Shunt resistor RSHUNT should be selected considering the accuracy of measuring current and the maximum power dissipation according to an application. If the value of shunt resistor is high, it minimizes the influence of offset and increases the accuracy of measuring current. If the value of shunt resistor is low, it reduces the power dissipation of VDD. www.rohm.com
TSZ02201
9
-0M2M0FC23030-1-2
© 2022 ROHM Co., Ltd. All rights reserved. /15 TSZ22111 • 15 • 001
19.Jan.2024 Rev.001
Document Outline General Description Features Applications Key Specifications Package Typical Application Circuit Pin Configuration Pin Descriptions Absolute Maximum Ratings Thermal Resistance Recommended Operating Conditions Electrical Characteristics Typical Performance Curves Timing Chart Application Example I/O Equivalence Circuits Operational Notes Ordering Information Marking Diagram Physical Dimension and Packing Information Revision History