6. Connectors Pinout

This section describes the pinout of all connectors on the foxBMS Master Unit.

6.1. Overview of the Connectors on the foxBMS Master Unit

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Fig. 6.1 Front view of the foxBMS Master Unit indicating the location of each pin header

foxBMS uses only Molex Micro-Fit 3.0 type connectors, except for USB. A comprehensive set of connectors and crimps is supplied with foxBMS to start connecting immediately. In case crimps or housings are missing, they are commonly available at major distributors.

Molex Micro-Fit 3.0 Crimps Part Number: 46235-0001 (Farnell 2284551)

Molex Micro-Fit 3.0 Connectors:

Pin Count Molex Housing Part Number Farnell Order Number
2 43025-0200 672889
4 43025-0400 672890
6 43025-0600 672907
10 43025-1000 672920
12 43025-1200 629285
16 43025-1600 9961321
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Fig. 6.2 Defined viewing direction for the connector pin out; receptable - rear view; header - front view (image source: MOLEX)

6.2. Supply (X201 on BMS-Master Board)

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Pin Signal Direction Description
1 SUPPLY_EXT2 Input 12 - 24V
2 SUPPLY_EXT2 Input 12 - 24V
3 GND_EXT2 Input GND
4 SUPPLY_EXT0 Input 12 - 24V
5 GND_EXT0 Input GND
6 GND_EXT2 Input GND
  • SUPPLY_EXT0 / GND_EXT0: Microcontroller supply and insulation monitoring devices supply
  • SUPPLY_EXT2 / GND_EXT2: Contactor supply and interlock supply

6.3. CAN0 (X801 on BMS-Master Board)

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Pin Signal Direction Description
1 GND_EXT0 Output  
2 NC  
3 CAN0_L Input/Output  
4 CAN0_H Input/Output  

Ground of CAN0 is shared with supply ground GND_EXT0. CAN0 is isolated from the MCU0 via the isolated CAN transceiver TJA1052. The CAN transceiver may be put into standby mode by MCU0.

6.4. CAN1 (X801 on BMS-Extension Board)

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Pin Signal Direction Description
1 GND_EXT1 Input  
2 SUPPLY_EXT1 Input  
3 CAN1_L Input/Output  
4 CAN1_H Input/Output  

CAN1 has to be supplied externally (GND_EXT1 / SUPPLY_EXT1) with 12 - 24V. CAN1 is isolated from the MCU0 via the isolated CAN transceiver TJA1052. The CAN transceiver may be put into standby mode by MCU0.

6.5. Insulation Monitor (Bender ISOMETER) (X701 on BMS-Master Board)

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Pin Signal Direction Description
1 BENDER_NEGATIVE_SUPPLY Output Supply to insulation monitoring device
2 SUPPLY_EXT0 Output Supply to insulation monitoring device
3 BENDER_OK_EXT Input Status signal of insulation monitoring device
4 BENDER_PWM_EXT Input Insulation monitoring device diagnostic signal

This interface is intended to be used with a Bender insulation monitoring device. Bender ISOMETER IR155-3203/-3204/-3210 are supported. The Bender ISOMETER is supplied and may be switched on or off (lowside) by the foxBMS Master Unit. By factory, the foxBMS Master Unit is configured to operate with the Bender ISOMETER IR155-3204/-3210. In order to operate with the Bender ISOMETER IR155-3203, Jumper R705 must be removed on BMS-Master Board. For more details, check the schematic of the BMS-Master Board in section Design Resources.

6.6. Contactors (X1201 - X1206 on BMS-Master Board and X1201 - X1203 on BMS-Extension Board)

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Pin Signal Direction Description
1 GND_EXT0 Contactor auxiliary contact
2 CONTACTOR_X_FEEDBACK_EXT Contactor auxiliary contact
3 CONTACTOR_X_COIL_POS Output Positive contactor coil supply
4 CONTACTORS_COMMON_NEG Output Negative contactor coil supply

All contactor connectors share one common ground. This common ground is switched lowside by the interlock circuit. Opening the interlock loop deactivates the contactor supply and opens all contactors. A contactor auxiliary contact may be read by connecting the auxiliary contact to the corresponding pins of the contactor connector.

Freewheeling diodes are not populated on the PCB, since some contactors like the Gigavac GX16 have built-in diodes and should not be used with additional external freewheeling diodes in parallel. If the used contactors do not have built-in freewheeling diodes, freewheeling diodes must be added to protect the contactor control circuitry. The load current is limited by the optically isolated power switch AQV25G2S (6A continuous load). Every contactor connector is fused with an onboard slow blow fuse type Schurter UMT-250 630mA (3403.0164.xx).

6.7. Interlock (X901 on BMS-Master Board)

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Pin Signal Direction Description
1 INTERLOCK_IN Input
2 INTERLOCK_OUT Output

The interlock circuit has a built-in current source, adjusted to 10mA constant current. In fault conditions, all contactors are opened by opening the interlock circuit. If the interlock circuit is externally opened, the contactor supply is deactivated immediately. This circuit has no effect on the foxBMS supply or communication interfaces.

6.8. Daisy Chain - Primary and Secondary (X1601 on BMS-Master Board)

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Hint

The pinout for the BMS-Interface Board hardware versions 1.1.0 and below is shown in table 6.1. For newer versions 1.2.0 and above see table 6.2.

Table 6.1 Daisy Chain Connector (Interface version 1.1.0 and below)
Pin Signal
1 NC
2 OUT+ (Secondary BMS-Slave Board)
3 OUT- (Secondary BMS-Slave Board)
4 NC
5 NC
6 OUT+ (Primary BMS-Slave Board)
7 OUT- (Primary BMS-Slave Board)
8 NC
9 NC
10 NC
11 NC
12 NC
13 NC
14 NC
15 NC
16 NC
Table 6.2 Daisy Chain Connector (Interface version 1.2.0 and above)
Pin Signal
1 OUT+ (Secondary BMS-Slave Board forward)
2 NC
3 OUT+ (Secondary BMS-Slave Board reverse)
4 NC
5 NC
6 OUT+ (Primary BMS-Slave Board forward)
7 NC
8 OUT+ (Primary BMS-Slave Board reverse)
9 OUT- (Secondary BMS-Slave Board forward)
10 NC
11 OUT- (Secondary BMS-Slave Board forward)
12 NC
13 NC
14 OUT- (Primary BMS-Slave Board forward)
15 NC
16 OUT- (Primary BMS-Slave Board reverse)

Please note that this connector pin out is only valid when the BMS-Interface Board uses the LTC6820 interfacing IC.

6.9. RS485 (X1301 on BMS-Extension Board)

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Pin Signal Direction Description
1 GND_EXT2 Output  
2 RS485_A Input/Output  
3 RS485_B Input/Output  
4 SUPPLY_EXT2 Output  
5 SUPPLY_EXT2 Input  
6 GND_EXT2 Input  

The RS485 interface uses the ESD rugged transceiver LT1785. Moreover, the interface is galvanically isolated. An external supply has to be provided (12 - 24V).

6.10. Isolated GPIO (X1901 on BMS-Extension Board)

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Pin Signal Direction Description
1 ISOGPIO_IN0 Input  
2 ISOGPIO_IN1 Input  
3 ISOGPIO_IN2 Input  
4 ISOGPIO_IN3 Input  
5 ISOGPIO_OUT0 Output  
6 ISOGPIO_OUT1 Output  
7 ISOGPIO_OUT2 Output  
8 ISOGPIO_OUT3 Output  
9 GND_EXT0 Output  
10 GND_EXT0 Output  

The BMS-Extension Board provides 4 isolated general purpose inputs and 4 isolated general purpose outputs. The GPIOs are isolated by an ADUM3402 (i.e., ESD rugged version of the ADUM1402). The inputs are equipped with 10kOhm pull down resistors and are intended for a maximum input voltage of 5V. The output voltage is also 5V. An external supply is not needed.

6.11. Isolated Normally Open Contacts - isoNOC (X2001 on BMS-Extension Board)

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Pin Signal Direction Description
1 ISONOC0_POSITIVE    
2 ISONOC1_POSITIVE    
3 ISONOC2_POSITIVE    
4 ISONOC3_POSITIVE    
5 ISONOC4_POSITIVE    
6 ISONOC5_POSITIVE    
7 ISONOC0_NEGATIVE    
8 ISONOC1_NEGATIVE    
9 ISONOC2_NEGATIVE    
10 ISONOC3_NEGATIVE    
11 ISONOC4_NEGATIVE    
12 ISONOC5_NEGATIVE    

The BMS-Extension Board features 6 isolated normally open contacts. The load current of each channel is limited by the optically isolated power switch AQV25G2S. The channels are not fused, however freewheeling diodes type GF1B are installed on board.

6.12. Analog Inputs (X1701 on BMS-Master Board)

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Pin Signal Direction Description
1 V_REF Output  
2 ANALOG_IN_CH0 Input  
3 V_REF Output  
4 ANALOG_IN_CH1 Input  
5 V_REF Output  
6 ANALOG_IN_CH2 Input  
7 V_REF Output  
8 ANALOG_IN_CH3 Input  
9 V_REF Output  
10 ANALOG_IN_CH4 Input  
11 GND0 Output  
12 GND0 Output  

On the BMS-Extension Board 4 nonisolated analog inputs to MCU0 are available. For applications using NTCs as temperature sensors, also a reference voltage of 2.5V is provided. The maximum input voltage is limited to 3.3V and is Zener protected. For further information on the input circuit, please refer to the foxBMS Master-Unit and to the foxBMS Design Resources.