Philips Universal Serial Bus ISP1122 - Manual (Page 5)

Philips Semiconductors
ISP1122
USB stand-alone hub
Product specification Rev. 03 — 29 March 2000 5 of 48
9397 750 07002 © Philips Electronics N.V. 2000. All rights reserved.
[1] Symbol names with an overscore (e.g. NAME) indicate active LOW signals.
[2] 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.
[3] See Table 4 “Mode selection” .
[4] To disable a downstream port connect both D
+
and D
−
to V
CC
via a 1 M
Ω
resistor; unused ports must
be disabled in reverse order starting from port 5.
[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).
[6] Downstream ports 1 and 2 cannot be disabled.
DP1 27 AI/O downstream port 1 D
+
connection (analog) [6]
DM0 28 AI/O upstream port D
−
connection (analog)
DP0 29 AI/O upstream port D
+
connection (analog)
DM2 30 AI/O downstream port 2 D
−
connection (analog) [6]
DP2 31 AI/O downstream port 2 D
+
connection (analog) [6]
PSW1/GL1 [3] 32 O 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: Pin description for SO32 and SDIP32 …continued
Symbol [1] Pin Type Description