10
ispMACH 4000ZE Pico Development Kit
Lattice Semiconductor
User’s Guide
Hardware Evaluation
How to evaluate hardware features of the on-board LC4256ZE.
Power Consumption
Tables 1 and 2 list a series of measurements for the CPLD I/O and core current running the Pico Power demonstra-
tion design when powered by battery or the USB cable interface.
CPLD power consumption can be measured by the on-board sensor circuits or by metering across resistors R34
(I/O, 100 ohm) and R35 (Core, 50 ohm) of the Pico board (see Figure 2). Use Ohm’s Law to calculate current from
the voltage drop across each resistor: I = V / R.
Note that voltmeter measurements reflect a lower static current level than what the on-board meter and PicoView
results display which accounts for the additional current that occurs when the POWR6AT6, current sense amplifi-
ers, and switch circuits are dynamically powered for a measurement.
The board will draw additional current when USB power is applied due to the LC4256ZE JTAG and I/O pins being
biased from surrounding USB support circuits. When powered by the battery cell, the LC4256ZE pins are isolated
by high-impedance circuits to minimize current leakage paths.
Table 1.
Feature
Static
Dynamic
I/O
Current
Core
Current
Pico Board
(LCD)
Counter
0000 - Decimal Up
0001 - Decimal Down
Current
Meter
1000 - CPLD Core (5 MHz)
1100 - CPLD Core
1001 - CPLD I/O
Shift
0010 - Left
0011 - Right
Voltage
Meter
1010 - USB 5V
1011 - Battery 3V
Standby
1111
Sample Current and Voltage Measurements – Battery Power
Table 2.
Feature
Static
Dynamic
I/O
Current
Core
Current
Pico Board
(LCD)
PicoView
I/O
Current
Core
Current
Counter
0000 - Decimal Up
0001 - Decimal Down
Current
Meter
1000 - CPLD Core (5 MHz)
1100 - CPLD Core
1001 - CPLD I/O
Shift
0010 - Left
0011 - Right
Voltage
Meter
1010 - USB 5V
1011 - Battery 3V
Standby
1111
Sample Current and Voltage Measurements - USB Power
0µA
390µA
N/A
1µA
624µA
768µA
490µA
704µA
688uA (I/O)
390µA
N/A
490µA
0V
2.88V
10µA
N/A
626uA
624µA
N/A
772µA
636µA
N/A
750µA
768µA (Core)
784µA
690µA
688µA (Core)
740µA
682µA
800µA (I/O)
693µA
624µA
N/A
781µA
640µA
N/A
690µA
4.96V
751µA
685µA
2.78V
450µA
N/A
450µA
