ISP1181 Ver la hoja de datos (PDF) - Philips Electronics
Número de pieza
componentes Descripción
fabricante
ISP1181 Datasheet PDF : 69 Pages
| |||
Philips Semiconductors
ISP1181
Full-speed USB interface
The USB connections D+ and D− remain powered and logically connected to the
USB bus. If a crystal oscillator is used, powering down during ‘suspend’ is managed
by the internal logic of ISP1181. When using an external oscillator on pin XTAL1, a
stable logic 1 level must be applied during ‘suspend’ state.
Figure 7 shows a typical bus-powered modem application using ISP1181 in
powered-on mode. The SUSPEND output is connected to the reset input (RST) of the
8031 microcontroller via an external inverter. This allows a ‘resume’ condition to wake
up the 8031 from power-down mode. The ISP1181 is woken up via the USB bus
(global resume) or by the ring detection circuit on the telephone line.
idth
VBUS
USB
VCC(5.0)
D+
D−
ISP1181
SUSPEND
WAKEUP
VCC 8031
RST
RING DETECTION
LINE
MGS781
Fig 7. SUSPEND and WAKEUP signals in a powered-on modem application.
11.1.2 Powered-off application
In powered-off application (PWROFF = 1 in the Hardware Configuration Register) the
supply of the CPU and other parts of the circuit is removed during ‘suspend’ state.
The SUSPEND output is active HIGH during ‘suspend’ state, making it suitable as a
power switch control signal, e.g. for an external oscillator.
Input pins of ISP1181 are pulled to ground via the pin buffers. Outputs are made
three-state to prevent current flowing in the application. Bi-directional pins are made
three-state and must be pulled to ground externally by the application. The power
supply of external pull-ups must also be removed to reduce power consumption.
handbook, full paGgeOwiSdtUh SP
WAKEUP
SUSPEND
2 ms
0.5 ms
Fig 8. Suspend and resume timing for powered-off application.
MGS782
9397 750 06896
Objective specification
Rev. 01 — 13 March 2000
© Philips Electronics N.V. 2000. All rights reserved.
20 of 69
Share Link: 