Document Reference No.: FT_000367
UM232H Single Channel USB Hi-Speed FT232H Development Module
Datasheet Version 1.2
Clearance No.: FTDI# 198
An alternative to connecting the pull-up network to the Reset pin, to prevent current from flowing back the
USB power bus line, is to connect the network ACBUS7 pin to achieve the same results but with additional
benefits. A function called PWRSAV# is used to prevent current from flowing the USB line in the same way as
connecting the reset to the a pull-up network. However, the PWRSAV# function has the additional feature
of being able to put FT232H into sleep mode when the USB host is powered down. There is one trade of o
using reset instead of PWRSAV#, in MPSSE mode the ACBUS7 pin can be selected as a GPIO pin, using this
pin from both PWRSAV# and GPIO mode can cause a conflict. PWRSAV# is enabled and disabled using the
EEPROM, this function is disabled by default. Figure 7.4 illustrates an alternative USB Self-Power
configuration.
5V or 3V3
5V
J1-1
J2-1
VIO
3V3
5V0
USB
PU2
PU1
MCU
ACBUS7
RXD
TXD
TXD
RXD
CTS#
RTS#
RTS#
CTS#
J2-14
J1-14
Figure 7.4 : Alternative Self-Powered Configuration – 5V0 External Supply
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