
Device Architecture
2- 94
Pr el iminar y v1 .7
Gate Driver
The Fusion Analog Quad includes a Gate Driver connected to the Quad's AG pin
(Figure 2-74).Designed to work with external p- or n-channel MOSFETs, the Gate driver is a configurable current
sink or source and requires an external pull-up or pull-down resistor. The AG supports 4 selectable
High Current Drive mode in which it can sink 20 mA; in this mode the switching rate is
approximately 1.3 MHz with 100 ns turn-on time and 600 ns turn-off time. Modeled on an open-
drain-style output, it does not output a voltage level without an appropriate pull-up or pull-down
resistor. If 1 V is forced on the drain, the current sinking/sourcing will exceed the ability of the
transistor, and the device could be damaged.
The AG pad is turned on via the corresponding GDONx pin in the Analog Block macro, where x is
the number of the corresponding Analog Quad for the AG pad to be enabled (GDON0 to GDON9).
The gate-to-source voltage (Vgs) of the external MOSFET is limited to the programmable drive
current times the external pull-up or pull-down resistor value (
EQ 2-5).Vgs ≤ Ig × (Rpullup or Rpulldown)
EQ 2-5
The rate at which the gate voltage of the external MOSFET slews is determined by the current, Ig,
sourced or sunk by the AG pin and the gate-to-source capacitance, CGS, of the external MOSFET. As
an approximation, the slew rate is given by
EQ 2-6.
dv/dt = Ig / CGS
EQ 2-6
Figure 2-74 Gate Driver
Analog Quad
AV
AC
AT
Voltage
Monitor Block
Current
Monitor Block
AG
Power
Line Side
Load Side
Digital
Input
Power
MOSFET
Gate Driver
Current
Monitor / Instr
Amplifier
Temperature
Monitor
Digital
Input
Digital
Input
Pads
To Analog MUX
To FPGA
(DAVOUTx)
To FPGA
(DACOUTx)
To FPGA
(DATOUTx)
On-Chip
Gate
Driver
Temperature
Monitor Block
Off-Chip
Rpullup
From FPGA
(GDONx)
Prescaler