ISP1181 Ver la hoja de datos (PDF) - Philips Electronics
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ISP1181 Datasheet PDF : 69 Pages
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Philips Semiconductors
ISP1181
Full-speed USB interface
Table 13: Pin states in powered-off application
Pin
Type
Appropriate state
A0
I/O (three-state) powered off; internally connected to ground (logic 0)
DATA[15:0]
I/O (three-state) powered off; internally connected to ground (logic 0)
SUSPEND
O
ISP1181 drives logic 1
WAKEUP
I
powered off; internally connected to ground (logic 0)
INT
O (three-state) powered off; internally connected to ground (logic 0)
RESET
I
externally driven [1] to logic 1
CS
I
powered off; internally connected to ground (logic 0)
RD
I
powered off; internally connected to ground (logic 0)
WR
I
powered off; internally connected to ground (logic 0)
XTAL1
I
powered off; internally connected to ground (logic 0)
CLKOUT
O (three-state) ISP1181 drives logic 0
[1] ‘Externally driven’ refers to logic outside the ISP1181.
When external components are powered-off, it is possible that interface signals RD,
WR and CS have unknown values immediately after leaving ‘suspend’ state. To
prevent corruption of its internal registers, ISP1181 enables a locking mechanism
once suspend is enabled.
After wake-up from suspend’ state, all internal registers except the Unlock Register
are write-protected. A special unlock operation is needed to re-enable write access.
This prevents data corruption during power-up of external components.
Figure 9 shows a typical bus-powered modem application using ISP1181 in
powered-off mode. The SUSPEND output is used to switch off power to the
microcontroller and other external circuits during ‘suspend’ state. The ISP1181 is
woken up via the USB bus (global resume) or by the ring detection circuit on the
telephone line.
idth
VBUS
USB
D+ VCC(5.0)
D−
ISP1181
power
switch
VCC
MICRO-
CONTROLLER
SUSPEND
WAKEUP
RING DETECTION
LINE
MGS783
Fig 9. SUSPEND and WAKEUP signals in a powered-off modem application.
9397 750 06896
Objective specification
Rev. 01 — 13 March 2000
© Philips Electronics N.V. 2000. All rights reserved.
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