ADBMS2950BCCSZ datasheet(67/97 Pages) AD

67 / 97 page

Data Sheet

ADBMS2950B

Rev. 0 | Page 67 of 97

APPLICATIONS

In some cases, the application circuits shown in this section are

simplified to show various concepts in a small space. Some

components may be omitted. Analog Devices offers full-

reference design circuits for the ADBMS2950B that are

validated against common requirements for industrial systems.

For full-reference designs and questions about specific use

cases, contact a local Analog Devices sales office.

TYPICAL APPLICATION

A typical application of the ADBMS2950B used in a battery

junction box is shown in Figure 46. It features the measurement

of battery pack voltage and current, high-voltage-system to

chassis-GND isolation resistance, link and precharge voltage

and shunt resistor temperature. The ADBMS2950B is put into

an isoSPI communication daisy-chain together with the

ADBMS6830B cell monitors according to Figure 20. GPOs are

used to control external high-voltage N-channel MOSFETS to

either reduce battery pack leakage when the system is shut

down or to toggle the bias states of the isolation resistance

measurement. An external I2C non-volatile memory is

connected to the GPIOs to store board calibration parameters

such as the shunt resistance or resistive-divider values.

The circuit in Figure 46 uses the VBAT1 input to measure the

overall battery pack voltage (BAT+ vs. BAT−). When the BMS

controller closes the relay toward the chassis-GND, and GPO6

toggles the MOSFET, the VBAT2 input can trace the voltage

response continuously and synchronously to the VBAT1

measurement, which enables isolation resistance measurement

in noisy environments with minimum error.

When the relay and the MOSFET are open, VBAT2 provides a

synchronous and continuous mean to measure the pack voltage

redundantly. However, where redundant pack voltage

monitoring is required permanently, also during isolation

resistance measurement, and accuracy of the redundant

measurement is key, VBAT2 might use a voltage divider

symmetric to the VBAT1 resistor network. The chassis-GND

measurement circuitry can then be connected to one of the V1

to V10 inputs. For good noise filtering, the BMS controller can

still trigger VxADC measurements during isolation resistance

measurement at a high rate and extract the synchronous

VBxADC measurements in software to perform the isolation

resistance calculations with minimum error.

Figure 46. Typical ADBMS2950B Application

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