Cyclone® V Device Handbook: Volume 1: Device Interfaces and Integration

ID 683375
Date 10/18/2023
Document Table of Contents

9.2. I/O Voltage for JTAG Operation

The Cyclone® V device operating in IEEE Std. 1149.1 BST mode uses four dedicated JTAG pins—TDI, TDO, TMS, and TCK. Cyclone® V devices do not support the optional TRST pin.

The TCK pin has an internal weak pull-down resistor, while the TDI and TMS pins have internal weak pull-up resistors. The 3.3-, 3.0-, or 2.5-V VCCPD supply of I/O bank 3A powers the TDO, TDI, TMS, and TCK pins. All user I/O pins are tri-stated during JTAG configuration.

The JTAG chain supports several different devices. Use the supported TDO and TDI voltage combinations listed in the following table if the JTAG chain contains devices that have different VCCIO levels. The output voltage level of the TDO pin must meet the specification of the TDI pin it drives.

Table 114.  Supported TDO and TDI Voltage CombinationsThe TDO output buffer for VCCPD of 3.3 V or 3.0 V meets VOH (MIN) of 2.4 V, and the TDO output buffer for VCCPD of 2.5 V meets VOH (MIN) of 2.0 V.
Device TDI Input Buffer Power (V) Cyclone® V TDO VCCPD
VCCPD  = 3.3 V VCCPD  = 3.0 V VCCPD  = 2.5 V
Cyclone® V VCCPD = 3.3 Yes Yes Yes
VCCPD = 3.0 Yes Yes Yes
VCCPD = 2.5 Yes Yes Yes
Non- Cyclone® V 26 VCC = 3.3 Yes Yes Yes
VCC = 2.5 Yes Yes Yes
VCC = 1.8 Yes Yes Yes
VCC = 1.5 Yes Yes Yes
26 The input buffer must be tolerant to the TDO VCCPD voltage.