NXP Semiconductors
AN10050
Designing a Hi-Speed USB host PCI adapter using ISP1562/63
AN10050_4
© NXP B.V. 2007. All rights reserved.
Application note
Rev. 04 — 1 November 2007
5 of 18
supply that pr5 V ± 5 % @ 2 A stabilized can be used. For example, a standard
hub power supply.
Note the distribution of pull-up resistors in the recommended schematics. For example,
to achieve correct functionality, it is recommended that you connect the pull-up resistors
placed on the PWEn_N and OCn_N input signals of the power switch, for example,
MIC2026, to DV
AUX
NET, maintaining a good condition of these signals even when
+3.3 V and +5 V are off. The ‘fault flag’ pins (OCn_N) of MIC2026 are open-drain and
require the presence of pull-up resistors. A 100 nF capacitor is used on each OCn_N
signal to prevent false fault conditions.
CLKRUN# is implemented in the ISP1562 on pin 42 and in the ISP1563 on pin 52. This
signal is targeted mainly for mobile system designs. CLKRUN is an I/O pin. It is used by
the system to safely turn-off the PCI CLK for power saving, with acknowledgment from
the ISP1562/3 according to a predefined protocol. In the case of the PCI adapter card
design, CLKRUN# must always be LOW because it is not present in the PCI connector.
CLKRUN# may directly be connected to GND. For details on CLKRUN# function, refer to
PCI Mobile Design Guide Version 1.1
.
3.2 Input clock: applies only to the ISP1563
You can use either of the following as clock input:
•
A 12 MHz crystal; the default recommended solution for best ElectroMagnetic
Interference (EMI) results.
•
A 48 MHz oscillator; this may be a useful alternative, typically, in the case of on-
motherboard design.
Both solutions for the input clock are shown in the schematics.
To use a 48 MHz clock as input, connect the clock signal to the ISP1563 pin 86 (XTAL1),
pin 87 (XTAL2) can be left open, and pin 121 (SEL48M) must be pulled up as shown in
the schematics.
In an add-on card configuration, normally, the 12 MHz crystal is used. In such a case,
oscillators OSC2 and R45 are not necessary. Also, pin 121 (SEL48M) must directly be
connected to GND. Another possibility is using a 12 MHz clock as an input. In this case,
the 12 MHz-clock signal is directly connected to the ISP1563 pin 86 (XTAL1). This is
similar to the case in which the 48 MHz clock is used; however, the ISP1563 pin 121
must still be connected to GND.
3.3 Selecting the number of ports: applies only to the ISP1563
The selection of the number of ports, 2 or 4, is done using the SEL2PORTS signal
(ISP1563 pin 5). It must be pulled to LOW, that is, connected to GND, for normal use of
all four ports. If SEL2PORTS is HIGH, only two ports, that is, port 1 and port 2, are
enabled; one port from each OHCI will be used in this case for performance
improvement. Details regarding the power consumption and possible power savings in a
two-port configuration can be found in the ISP1563 data sheet.
3.4 Subsystem vendor ID and subsystem device ID
The ISP1562/3 allows loading of the Subsystem Vendor ID (VID) and the Subsystem
Device ID (DID) for both EHCI and OHCI from an external EEPROM. Loading of these
values in the configuration registers of the ISP1562/3 will occur only if a value of 15h is
found in byte 7 of the EEPROM. The necessary signals, I
2
C-bus clock and I
2
C-bus data,
