Output signal
PBIASLITEPWRDNZ0/GPIO_IO_PWRDNZ
SDMMC1_VDDS/SIM_VDDS
VDDS
CONTROL_PADCONF_x
Pull
MODE
SDMMC1_VDDS/SIM_VDDS
oe
Input signal
PBIAS voltage
scm-016
Public Version
SCM Functional Description
www.ti.com
Figure 13-13. Extended-Drain I/O
The extended-drain I/O cells have the following I/O signals:
•
Output signal, input signal, and oe, which comes from the selected IO module with the correct MODE
field CONTROL.
configuration.
NOTE:
The two extended-drain I/Os are muxed I/Os with mode and pullup/pulldown configurations
programmable in the SCM.
•
The PBIAS voltage is a voltage reference for biasing the extended-drain in the MMC/SD/SDIO1I/O and
GPIO-associated I/O cells (gpio_126, gpio_127, and gpio_129).
•
The PBIASLITEPWRDNZ0 bit is used to protect the MMC/SD/SDIO1 I/O cell when the
SDMMC1_VDDS voltage is not stable.
•
The GPIO_IO_PWRDNZ bit is used to protect the GPIO-associated I/O cell when the SIM_VDDS
voltage is not stable.
CAUTION
Software
must
keep
the
PWRDNZ-related
signals
to
0b0
when
the
SDMMC1_VDDS or SIM_VDDS signal is ramping up/down or changing. When
PBIASLITEPWRDNZ0/PBIASLITEPWRDNZ1 is 0, the PAD is floating (the PAD
may not reflect the state of the output signal, and the input signal may not
reflect the state of the PAD).
CAUTION
It
is
strongly
recommended
to
synchronize
any
changes
of
the
PBIASLITEPWRDNZ1 and GPIO_IO_PWRDNZ bits (that is, both bits should
be set to 1 or 0 at the same time).
•
The CONTROL.
[20] PRG_SDMMC1_SPEEDCTRL bit controls the speed of
the MMC/SD/SDIO1 I/O cell and can be used to reduce dynamic current if fast rise/fall times are not
required.
2470
System Control Module
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated