Philips Semiconductors
ISP1122A
USB stand-alone hub
Pin description for SO32 and SDIP32
…continued
Pin
28
29
30
31
32
Type
AI/O
AI/O
AI/O
AI/O
O
Description
upstream port D− connection (analog)
upstream port D+ connection (analog)
downstream port 2 D− connection (analog)
[6]
downstream port 2 D+ connection (analog)
[6]
modes 4 to 6:
power switch control output for downstream
port 1 (open-drain, 6 mA)
modes 0 to 3, 7:
GoodLink LED indicator output for
downstream port 1 (open-drain, 6 mA); to connect an LED
use a 330
Ω
series resistor
Table 2:
DM0
DP0
DM2
DP2
Symbol
[1]
PSW1/GL1
[3]
[1]
[2]
[3]
[4]
[5]
[6]
Symbol names with an overscore (e.g. NAME) indicate active LOW signals.
The voltage at pin V
reg(3.3)
is gated by the RESET pin. This allows fully self-powered operation by
connecting RESET to V
BUS
(+5 V USB supply). If V
BUS
is lost upstream port D+ will not be driven.
See
Table 4 “Mode selection”.
To disable a downstream port connect both D+ and D− to V
CC
via a 1 MΩ resistor; unused ports must
be disabled in reverse order starting from port 5.
Analog detection circuit can be switched off using an external EEPROM, see
Table 23;
in this case,
the pin functions as a logic input (TTL level).
Downstream ports 1 and 2 cannot be disabled.
9397 750 06986
© Philips Electronics N.V. 2000. All rights reserved.
Preliminary specification
Rev. 01 — 27 March 2000
5 of 48
PHILIPS [ NXP SEMICONDUCTORS ]
