isp1520 NXP Semiconductors, isp1520 Datasheet - Page 13

• Manufacturer Part Number: isp1520
• Description: Hi-speed Universal Serial Bus Hub Controller
• Manufacturer: NXP Semiconductors

Philips Semiconductors
ISP1520_4
Product data sheet
Fig 6. Typical voltage drop components in self-powered mode using global overcurrent detection
(1) Includes PCB traces, ferrite beads, and so on.
POWER SUPPLY
5.1 V KICK-UP
3 % regulated
8.1.3 Overcurrent protection mode
+
PSWn_N pins have integrated weak pull-up resistors inside the chip.
Table 5.
The ISP1520 supports all overcurrent protection modes: none, global and individual.
No overcurrent protection mode reporting is selected when pin NOOC = HIGH. Global
and individual overcurrent protection modes are selected using pins PSWn_N, following
power switching modes selection scheme; see
For global overcurrent protection mode, only PSW1_N and OC1_N are active; that is, in
this mode, the remaining overcurrent indicator pins are disabled. To inhibit the analog
overcurrent detection, OC_N pins must be connected to V
Table 6.
Both analog and digital overcurrent modes are supported; see
For digital overcurrent detection, the normal digital TTL level is accepted on overcurrent
input pins. For analog overcurrent detection, the threshold is given in
mode, to filter out false overcurrent conditions because of in rush and spikes, a dead time
of 15 ms is built into the IC, that is, overcurrent must persist for 15 ms before it is reported
to the host.
Table 7.
Power switching mode
Ganged
Individual
Power switching mode NOOC
None
Global
Individual
Pin ADOC
3.3 V or 5.0 V
Ground
4.95 V (min)
for overcurrent
sense resistor
voltage drop
low-ohmic
detection
100 mV
Power switching mode: pin configuration
Overcurrent protection mode pin configuration
Overcurrent detection mode selection pin configuration
power switch
(PSWn_N)
ISP1520
Rev. 04 — 28 April 2006
Mode selection
analog
digital
HIGH
LOW
LOW
PSW1_N
internal pull-up
internal pull-up
voltage drop
75 mV
PSW1_N
ground
internal pull-up
internal pull-up
PMOS switch
low-ohmic
PSW2_N
ground
internal pull-up
resistance
voltage drop
hub board
25 mV
Table
PSW2_N
ground
ground
internal pull-up internal
(1)
6.
4.75 V (min)
Description
threshold V
normal digital TTL level
REF(5V0)
PSW3_N
ground
internal pull-up
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Hi-Speed USB hub controller
Table
V
D+
D
GND
SHIELD
PSW3_N
ground
ground
pull-up
BUS
004aaa262
.
trip
7.
Section
ISP1520
downstream
connector
PSW4_N
ground
internal pull-up
PSW4_N
ground
ground
internal
pull-up
port
14. In this
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