Device Architecture
Current Monitor
The Fusion Analog Quad is an excellent element for voltage- and current-monitoring applications.
In addition to supporting the same functionality offered by the AV pad, the AC pad can be
configured to monitor current across an external sense resistor (Figure 2-70). To support this
current monitor function, a differential amplifier with 10x gain passes the amplified voltage drop
between the AV and AC pads to the ADC. The amplifier enables the user to use very small resistor
values, thereby limiting any impact on the circuit. This function of the AC pad does not limit AV
pad operation. The AV pad can still be configured for use as a direct voltage input or scaled
through the AV prescaler independently of it’s use as an input to the AC pad’s differential
amplifier.
Power
Off-Chip
AV
AC
AG
AT
Voltage
Monitor Block
Current
Monitor Block
Gate
Driver
Temperature
Monitor Block
Pads
On-Chip
Analog Quad
Prescaler
Prescaler
Prescaler
Power
MOSFET
Gate Driver
Digital
Input
Digital
Input
Digital
Input
Current
Monitor / Instr
Amplifier
Temperature
Monitor
To FPGA
(DAVOUTx)
To FPGA
(DACOUTx)
From FPGA
(GDONx)
To FPGA
(DATOUTx)
To Analog MUX
To Analog MUX
To Analog MUX
Figure 2-70 • Analog Quad Current Monitor Configuration
2-90
Preliminary v1.7
ACTEL [ Actel Corporation ]
