Device Architecture
Table 2-36 • Analog Block Pin Description (continued)
Number
of Bits
Location of
Details
Signal Name
Direction
Function
ATRETURN67
1
Input
Temperature monitor return shared Analog Quad
by Analog Quads 6 and 7
AV7
1
1
1
1
1
1
1
1
1
Input
Input
Analog Quad 7
Analog Quad
Analog Quad
Analog Quad
Analog Quad
Analog Quad
Analog Quad
Analog Quad
Analog Quad
AC7
AG7
Output
Input
Input
Input
AT7
AV8
Analog Quad 8
AC8
AG8
Output
Input
Input
AT8
ATRETURN89
Temperature monitor return shared Analog Quad
by Analog Quads 8 and 9
AV9
1
1
1
1
1
1
2
1
1
Input
Input
Analog Quad 9
Analog Quad
Analog Quad
Analog Quad
Analog Quad
RTC
AC9
AG9
Output
Input
AT9
RTCMATCH
RTCPSMMATCH
RTCXTLMODE[1:0]
RTCXTLSEL
RTCCLK
Output
Output
Output
Output
Input
MATCH
MATCH connected to VRPSM
Drives XTLOSC RTCMODE[1:0] pins
Drives XTLOSC MODESEL pin
RTC clock input
RTC
RTC
RTC
RTC
Analog Quad
With the Fusion family, Actel introduces the Analog Quad, shown in Figure 2-65 on page 2-85, as
the basic analog I/O structure. The Analog Quad is a four-channel system used to precondition a set
of analog signals before sending it to the ADC for conversion into a digital signal. To maximize the
usefulness of the Analog Quad, the analog input signals can also be configured as LVTTL digital
input signals. The Analog Quad is divided into four sections.
The first section is called the Voltage Monitor Block, and its input pin is named AV. It contains a
two-channel analog multiplexer that allows an incoming analog signal to be routed directly to the
ADC or allows the signal to be routed to a prescaler circuit before being sent to the ADC. The
prescaler can be configured to accept analog signals between –12 V and 0 or between 0 and +12 V.
The prescaler circuit scales the voltage applied to the ADC input pad such that it is compatible with
the ADC input voltage range. The AV pin can also be used as a digital input pin.
The second section of the Analog Quad is called the Current Monitor Block. Its input pin is named
AC. The Current Monitor Block contains all the same functions as the Voltage Monitor Block with
one addition, which is a current monitoring function. A small external current sensing resistor
(typically less than 1 Ω) is connected between the AV and AC pins and is in series with a power
source. The Current Monitor Block contains a current monitor circuit that converts the current
through the external resistor to a voltage that can then be read using the ADC.
The third part of the Analog Quad is called the Gate Driver Block, and its output pin is named AG.
This section is used to drive an external FET. There are two modes available: a High Current Drive
mode and a Current Source Control mode. Both negative and positive voltage polarities are
available, and in the current source control mode, four different current levels are available.
2-84
Preliminary v1.7
ACTEL [ Actel Corporation ]
