Copyright © 2015 Avnet, Inc. AVNET and the AV logo are registered trademarks of Avnet, Inc. All other brands are property of their respective owners.
Avnet Electronics Marketing 21 of 28 Rev D 24 Apr 2015
2.7 Power
The Texas Instruments TPS65708 provides two high-efficiency switching converters, two LDOs, and an LED
driver. The output voltages are tuned internally on the device. The default values are 3.3V and 1.8V for the
switchers and 2.8V and 1.2V for the LDOs. In this implementation, the 2.8V LDO output is not utilized.
The Spartan-6 FPGA core voltage requires 1.2V. Estimated max current is 160mA. This is supplied by LDO2
on the TPS65708. The input voltage is the 1.8V generated by DCDC2.
The DCDC2 regulator generates 1.8V. This voltage powers the Mobile DDR, FPGA Vcco, and the LDO2
source. Estimated max current is 210mA, plus the 160mA that the 1.2V LDO needs.
The DCDC1 regulator generates 3.3V. This voltage powers the Flash, Ethernet, PMODs, Vcco_0, Vcco_1, and
Vcco_2. Estimated max current for the board circuits is 370mA, which includes 50mA for each PMOD.
The TPS65708 has built-in sequencing, resulting in a power-up sequence of 3.3V 1.8V 2.8V 1.2V.
Figure 9 – TPS65708 Connections
2.7.1 Power Good LED
A Green status LED is used to indicate when power is good on the board. This is tied to the ISINK of the
TPS65708, while the PWM input to the LED driver is connected to the 1.2V supply. This ensures that the
Power Good LED reflects the true sequencing status of all supplies.
To Next Page
Loading...
Need help?
General