PLUS
ProASIC
Flash Family FPGAs
V
Programming Supply Pin
finite length conductors that distribute the power to the
device. This can be accomplished by providing sufficient
bypass capacitance between the VPP and VPN pins and
GND (using the shortest paths possible). Without
sufficient bypass capacitance to counteract the
inductance, the VPP and VPN pins may incur a voltage
spike beyond the voltage that the device can withstand.
This issue applies to all programming configurations.
PP
This pin may be connected to any voltage between GND
and 16.5 V during normal operation, or it can be left
unconnected.2 For information on using this pin during
programming,
ProASICPLUS Devices application note. Actel recommends
floating the pin or connecting it to VDDP
see
the
In-System Programming
.
V
Programming Supply Pin
PN
The solution prevents spikes from damaging the
ProASICPLUS devices. Bypass capacitors are required for
the VPP and VPN pads. Use a 0.01 µF to 0.1 µF ceramic
capacitor with a 25 V or greater rating. To filter low-
frequency noise (decoupling), use a 4.7 µF (low ESR, <1
<Ω, tantalum, 25 V or greater rating) capacitor. The
capacitors should be located as close to the device pins as
possible (within 2.5 cm is desirable). The smaller, high-
frequency capacitor should be placed closer to the device
pins than the larger low-frequency capacitor. The same
dual-capacitor circuit should be used on both the VPP and
VPN pins (Figure 1-49).
This pin may be connected to any voltage between 0.5V
and –13.8 V during normal operation, or it can be left
unconnected.3 For information on using this pin during
programming,
see
the
In-System Programming
ProASICPLUS Devices application note. Actel recommends
floating the pin or connecting it to GND.
Recommended Design Practice
for V /V
PN PP
PLUS
PLUS
ProASIC
Devices – APA450, APA600,
ProASIC
APA300
Devices – APA075, APA150,
APA750, APA1000
Bypass capacitors are required from VPP to GND and VPN
to GND for all ProASICPLUS devices during programming.
During the erase cycle, ProASICPLUS devices may have
current surges on the VPP and VPN power supplies. The
only way to maintain the integrity of the power
distribution to the ProASICPLUS device during these
current surges is to counteract the inductance of the
These devices do not require bypass capacitors on the VPP
and VPN pins as long as the total combined distance of
the programming cable and the trace length on the
board is less than or equal to 30 inches. Note: For trace
lengths greater than 30 inches, use the bypass capacitor
recommendations in the previous section.
2.5cm
_
+
V
PP
0.1µF
+
+
to
4.7µF
4.7µF
Programming
Header
or
Actel
ProASIC
Device
0.01µF
PLUS
Supplies
_
+
V
PN
0.1µF
to
0.01µF
Figure 1-49 • ProASICPLUS VPP and VPN Capacitor Requirements
2. There is a nominal 40 kΩ pull-up resistor on VPP.
3. There is a nominal 40 kΩ pull-down resistor on VPN
.
1-74
v5.2
ACTEL [ Actel Corporation ]
