Philips Semiconductors
ISP1122A
USB stand-alone hub
Table 2: Pin description for SO32 and SDIP32…continued
Symbol [1]
Pin Type Description
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
[1] Symbol names with an overscore (e.g. NAME) indicate active LOW signals.
[2] The voltage at pin Vreg(3.3) is gated by the RESET pin. This allows fully self-powered operation by
connecting RESET to VBUS (+5 V USB supply). If VBUS 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 VCC via a 1 MΩ 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.
9397 750 06986
Preliminary specification
Rev. 01 — 27 March 2000
© Philips Electronics N.V. 2000. All rights reserved.
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