Introduction

The document here explains the data and electrical interface between the ADCS and other subsystems, including Power, CDH and mechanical. The electrical and data interfaces of the ADCS subsystem are demonstrated below.

ADCS-POW Electrical and Data Interface

Electrical Interface

Figure 2 shows that electric power is provided to ADCS from POW through a load distribution. The switch is controlled internally by the EPS controller and connects the ADCS_POWER_POS terminal to the Main Power bus (MPB) when closed. The ADCS should be supplied with 3.3V and 5V. Both supplies must be switched on simultaneously.

R-INT-0691: The ADCS subsystem shall not have a power consumption of more than 62.08 Wmin per orbit.

R-INT-0233: The ADCS subsystem shall use no more than 0.67 W.

ADCS-POW Electrical Interface Specifications

• MPB Voltage: 4.0 V to 7.3 V (Pending Change to actual range)

ADCS-POW Data Interface

The data (communication) interface between ADCS and POW occurs through a 4-wire SPI connection. On the ADCS side, the SPI lines(Texas Instruments MSP430FR2476PT) connect directly to the ADCS module microcontroller .

MSP430FR2476 SPI Specifications

• Operating voltage: 3.0 V

• SPI type: 4-wire (MOSI, MISO, SCLK, CS)

• SPI Clock frequency: up to 8 MHz

• SOMI data setup time: 40 ns (master mode)

• SIMO data valid time: 20 ns (master mode)

• SIMO data setup time: 12 ns (slave mode)

• SOMI data valid time: 42 ns (slave mode)

ADCS Data Switch(SN74CBTLV3257-EP) Specifications

• Voltage rating: -0.5 V to 4.6 V

• Latching current limit: TBD

• ON Resistance: 89 mohms

• Turn on delay: < 315 microseconds

• Turn off delay: < 15 microseconds

References

"SIGMA ACS Operations Manual", Sumin Alicia Hong, Patrick Irvin, York University