USB2422 Datasheet, PDF (9/47 Pages) SMSC Corporation – 2-Port USB 2.0 Hi-Speed Hub Controller

USB2422
TABLE 2-2: USB2422 PIN DESCRIPTIONS (CONTINUED)
Pin #
Symbol
Buffer Type
Description
MISC
22
XTALIN/
CLKIN
21
XTALOUT
ICLKx
OCLKx
24 MHz Crystal or External Clock Input:
This pin connects to either one terminal of the crystal or to an external
24 MHz clock when a crystal is not used.
Crystal Output:
15
RESET_N
This is the other terminal of the crystal circuit with 1.2 V p-p output and
a weak (< 1 mA) driving strength. When an external clock source is
used to drive XTALIN/CLKIN, leave this pin unconnected, or use with
appropriate caution.
IS
RESET Input:
6
NC
17
SUSP_IND
IPD
I/O12
The system must reset the chip by driving this input low. The minimum
active low pulse is 1 μs.
Treat as a no connect pin or connect to ground. No trace or signal
should be routed or attached to this pin.
Suspend Indicator:
Indicates the USB state of the hub.
LOCAL_PWR
negated : unconfigured, or configured and in USB Suspend
asserted : Hub is configured, and is active (i.e., not in suspend)
Local Power:
This input selects whether the hub reports itself as bus or self-powered
when dynamic power switching is enabled via the Dynamic Power
Enable (DYNAMIC) bit of the Configuration Data Byte 2 Register
(CFG2). This pin is sampled at POR/Reset before the USB Hub Attach
command is sent. Once the hub has entered the attach state (as
indicated by the USB Attach and Write Protect (USB_ATTACH) bit of the
Status/Command Register (STCD)), this pin cannot be changed.
Low : self/local power source is not available (i.e., the Hub gets all
power from the upstream USB VBus).
(NON_REM0)
High : self/local power source is available.
Note: Never tie this pin directly to VDD33, as doing so may cause it
to act as SUSP_IND.
Note:
This pin assumes the meaning of local power input only if
properly configured via SMBus. If the hub is configured via
straps, it is NON_REM0 at reset and SUSP_IND after reset.
Non-Removable Port Strap Option:
This pin is sampled (in conjunction with SUSP_IND/NON_REM0) at
RESET_N negation to determine if ports [2:1] contain permanently
attached (non-removable) devices:
NON_REM[1:0] = 00: all ports are removable
NON_REM[1:0] = 01: port 1 is non-removable
NON_REM[1:0] = 10: ports 1 and 2 are non-removable
NON_REM[1:0] = 11: reserved
See Section 2.5, "Strap Pin Configuration" for details.
 2013 - 2015 Microchip Technology Inc.
DS00001726B-page 9