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[FAQ] What precision amplifiers are right for a Battery Management System (BMS)?

Other Parts Discussed in Thread: OPA322-Q1, OPA320-Q1, OPA388-Q1, TLV197-Q1, OPA197-Q1, OPA192-Q1, OPA317-Q1, OPA333-Q1, OPA180-Q1, OPA376-Q1

A Battery Management System (BMS) is responsible for monitoring the health of battery cells by measuring temperature and detecting current leaks or overcurrent conditions. Additionally, the BMS manages voltage levels in individual cells such that energy from discharging, charging, or recovered from regenerative breaking is distributed or sourced evenly to prolong system lifespan.



Current Sensing:
It’s important for the current sensing amplifier to be able to monitor current quickly and detect leakage/overcurrent as it occurs. For this a faster transient response is required from amplifiers with a high slew rate and wide bandwidth.

Table 1: Amplifier recommendations for current sensing OPA388-Q1 OPA320-Q1 OPA322-Q1

Number of
Channels

Vs min
 (V)

Vs max
(V)

GBW typ
(MHz)

Slew Rate
typ (V/µs)

Vos max
@25°C (mV)

OPAx388-Q1
Ultimate Precision

1,2

1.8

5.5

10

5

0.005

OPAx320-Q1

1,2

1.8

5.5

20

10

0.15

OPAx322-Q1
Cost Sensitive

1,2,4

1.8

5.5

20

10

2



High Voltage Diagnostics:
As the name implies the HV Diagnostics socket requires a high voltage component to measure both voltage and current. The amplifier should also have a wide bandwidth and minimize offset/noise.

Table 2: Amplifier recommendations for high voltage diagnostics OPA192-Q1 OPA197-Q1 TLV197-Q1

Number of
Channels

Vs min
 (V)

Vs max
(V)

Vos max
@25°C (mV)

Drift typ
(µV/°C)

Vn typ
(nV/√Hz)

OPAx192-Q1

1,2

4.5

36

0.025

0.1

5.5

OPAx197-Q1

1,2,4

4.5

36

0.25

.5

5.5

TLVx197-Q1
Cost Sensitive

1,2,4

4.5

36

0.5

1

5.5



Cell Supervision:
Battery monitoring via cell supervision is necessary for monitoring the balanced distribution of energy among cells and for current faults and leakage. Unlike the current sensing socket here accurate measurements with low offset voltage and drift take priority over speed with no bandwidth requirements.

Table 3: Amplifier recommendations for cell supervision OPA180-Q1 OPA333-Q1 OPA317-Q1

Number of
Channels

Vs min
 (V)

Vs max
(V)

Vos max
@25°C (mV)

Drift typ
(µV/°C)

IBias typ
(pA)

Vn typ
(nV/√Hz)

OPAx180-Q1

1,2

1.8

5.5

0.075

0.1

250

10

OPAx333-Q1

1,2

1.8

5.5

0.01

0.02

70

55

OPAx317-Q1
Cost Sensitive

1,2

1.8

5.5

0.09

0.05

200

55



Temperature Sensing:
Because temperature is not constant throughout the entire system safe designs will include multiple amplifiers connecting thermistors to an ADC or MCU. To address settling issues the ADC-driving amplifier should have low drift over temperature.

Table 4: Amplifier recommendations for cell temperature sensing 

Number of
Channels

Vs min
 (V)

Vs max
(V)

Vos max
@25°C (mV)

Drift typ
(µV/°C)

IBias typ
(pA)

Vn typ
(nV/√Hz)

OPAx376-Q1

1,2,4

2.2

5.5

0.025

0.32

0.2

7.5

OPAx333-Q1

1,2

1.8

5.5

0.01

0.02

70

55

OPAx317-Q1
Cost Sensitive

1,2

1.8

5.5

0.09

0.05

200

55




High Voltage Safety Interlock:
Safety Interlock components should be as accurate as possible in their monitoring, Zero-Drift or low-drift components are ideal here. Ideally non-chopper, low-drift amplifiers such as the OPA376-Q1 would be used here as choppers are prone to glitches caused by uneven spikes in the input bias current. This phenomenon can be addressed, however, by matching impedances.

Table 5: Amplifier recommendations for high voltage safety interlock

Number of 
Channels

Vs min
 (V)

Vs max
(V)

Vos max
@25°C (mV)

Drift typ
(µV/°C)

Vn
(nV/√Hz)

OPAx333-Q1

1,2

1.8

5.5

0.01

0.02

70

OPAx376-Q1

1,2,4

2.2

5.5

0.025

0.32

7.5

OPAx377-Q1
Cost Sensitive

1,2,4

2.2

5.5

1

0.32

7.5




For useful resources and additional information, please make sure to check out the following content:

HEV/EV battery management systems explained simply (Technical Article)

Voltage and current sensing in HEV/EV applications (Technical Article)

Understanding current sensing in HEV/EV batteries (Technical Article)

Battery management system (BMS)  (Reference Design)

TI Battery Management Video Series (Video Series)

BMS EE Slides (End Equipment Slides)