isp1704a NXP Semiconductors, isp1704a Datasheet - Page 11

• Manufacturer Part Number: isp1704a
• Description: Ulpi Hi-speed Usb Transceiver
• Manufacturer: NXP Semiconductors

NXP Semiconductors
ISP1704A_1
Product data sheet
8.7.2.1 V
8.7.2.2 Session valid comparator
8.7.1 ID detector
8.7.2 V
8.7 OTG module
When the ISP1704A is put into UART mode, it acts as a voltage level shifter between the
following pins:
This module contains several sub-blocks that provide all the functionality required by the
USB OTG specification. Specifically, it provides the following circuits:
The ID detector detects which end of the micro-USB cable is plugged in. The ID detector
must first be enabled by setting the ID_PULLUP register bit to logic 1. If the ISP1704A
senses a value on the ID pin that is different from the previously reported value, an
RXCMD status update will be sent to the USB link, or an interrupt will be asserted.
The ID pin has a weak pull-up resistor (R
floating condition.
The ISP1704A provides three comparators to detect the V
comparators are explained in the following subsections.
This comparator is used by hosts and A-devices to determine whether the voltage on
V
comparator is 4.4 V. Any voltage on V
During power-up, it is expected that the comparator output will be ignored.
The session valid comparator is a TTL-level input that determines when V
enough for a session to start. Peripherals, A-devices and B-devices use this comparator to
detect when a session is started. The A-device also uses this comparator to determine
when a session is completed. The session valid threshold of the ISP1704A is between
0.8 V to 2.0 V.
•
•
•
•
•
•
•
BUS
BUS
BUS
From DATA0 (V
From DP (2.7 V level) to DATA1 (V
The ID detector to sense the ID pin of the micro-USB cable. The ID pin dictates which
device is initially configured as a host and which as a peripheral.
V
detection, SRP and HNP.
Resistors to temporarily charge and discharge V
If the micro-B end of the cable is plugged in (or nothing is plugged in), the ISP1704A
will report that ID_GND is logic 1. The USB link must be in the B-device state.
If the micro-A end of the cable is plugged in, the ISP1704A will report that ID_GND is
logic 0. The USB link must be in the A-device state.
BUS
is at a valid level for operation. The ISP1704A minimum threshold for the V
valid comparator
comparators
comparators to determine the V
CC(I/O)
Rev. 01 — 28 July 2008
level) to DM (2.7 V level) for the UART TXD signaling path.
BUS
CC(I/O)
weakPU(ID)
BUS
below this threshold is considered invalid.
level) for the UART RXD signaling path.
voltage level. This is required for the V
) permanently enabled to avoid the
BUS
. This is required for SRP.
BUS
voltage level. The
ULPI HS USB transceiver
ISP1704A
© NXP B.V. 2008. All rights reserved.
BUS
is high
BUS
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BUS
valid