ZCU111 Board User Guide 23
UG1271 (v1.1) August 6, 2018 www.xilinx.com
Chapter 3: Board Component Descriptions
Encryption Key Battery Backup Circuit
The XCZU28DR RFSoC U1 implements bitstream encryption key technology. The ZCU111
board provides the encryption key backup battery circuit shown in Figure 3-1.
The Seiko TS518FE rechargeable 1.5V lithium button-type battery B1 is soldered to the
board with the positive output connected to the XCZU28DR-2E RFSoC U1 V
CC_PSBATT
pin
Y23. The battery supply current I
BATT
specification is 150 nA maximum when board power is
off. B1 is charged from the UTIL_1V8 1.8V rail through a series diode with a typical forward
voltage drop of 0.38V and 4.7 ΩK current limit resistor. The nominal charging voltage is
1.42V.
X-Ref Target - Figure 3-1
Figure 3-1: Encryption Key Backup Circuit