Lattice Semiconductor ispXPGA Family Data Sheet
20
pattern by a device programmer, securing proprietary designs from competitors. The entire device must be erased
in order to erase the security scheme.
Density Shifting
The ispXPGA family has been designed to ensure that different density devices in the same package have the
same pin-out. Furthermore, the architecture ensures a high success rate when performing design migration from
lower density parts to higher density parts. In many cases, it is possible to shift a lower utilization design targeted
for a high-density device to a lower density device. However, the exact details of the final resource utilization will
impact the likely success in each case.
Temperature Sensing Diode
The built-in temperature-sensing diodes allow junction temperature to be measured during device operation. A pair
of pins (DXp and DXn) are dedicated for monitoring device junction temperature. The measurement is done by
forcing 10 µA and 100 µA current in the forward direction, and then measuring the resulting voltage. The voltage
decreases with increasing temperature at approximately 1.64 mV/°C. A typical device with a 85°C junction temper-
ature will measure approximately 593 mV.
The temperature-sensing diode works for the entire operating range as shown in Figure 22 - Sensing Diode Volt-
age-Temperature Relationship. Refer to Lattice’s Thermal Management document for thermal coefficients. Also
refer to Lattice technical note number TN1043, Power Estimation in ispXPGA Devices.
Figure 22. Sensing Diode Voltage-Temperature Relationship
Voltage
Junction Temperature (°C)
0.50
0.60
0.70
0.80
-50 0 50 100
125
-25
25
75
0.85
0.65
0.75
0.55
100 uA
10 uA
