參數(shù)資料
型號(hào)： ISP1123
廠商： NXP Semiconductors N.V.
英文描述： Universal Serial Bus compound hub
中文描述： 通用串行總線復(fù)合樞紐
文件頁(yè)數(shù)： 23/49頁(yè)
文件大?。?/td> 1155K
代理商： ISP1123
Philips Semiconductors
ISP1123
USB compound hub
Preliminary specification
Rev. 01 — 5 October 1999
23 of 49
9397 750 06325
Philips Electronics N.V. 1999. All rights reserved.
12. Hub power modes
USB hubs can either be self-powered or bus-powered.
Self-powered —
Self-powered hubs have a 5 V local power supply on board which
provide power to the hub and the downstream ports. The USB Specification Rev. 1.1
requires that these hubs limit the current to 500 mA per downstream port and report
overcurrent conditions to the host. The hub may optionally draw 100 mA from the
USB supply (V
BUS
) to power the interface functions (
hybrid-powered
).
Bus-powered —
Bus-powered hubs obtain all power from the host or an upstream
self-powered hub. The maximum current is 100 mA per downstream port. Current
limiting and reporting of overcurrent conditions are both optional.
Power switching of downstream ports can be done
individually
or
ganged
, where all
ports are switched simultaneously with one power switch. The ISP1123 supports both
modes, which can be selected using input INDV (see
Table 4
).
12.1 Voltage drop requirements
12.1.1
Self-powered hubs
Self-powered hubs are required to provide a minimum of 4.75 V to its output port
connectors at all legal load conditions. To comply with Underwriters Laboratory Inc.
(UL) safety requirements, the power from any port must be limited to 25 W (5 A at
5 V). Overcurrent protection may be implemented on a global or individual basis.
Assuming a 5 V
±
3% power supply the worst case supply voltage is 4.85 V. This only
allows a voltage drop of 100 mV across the hub printed-circuit board (PCB) to each
downstream connector. This includes a voltage drop across:
Power supply connector
Hub PCB (power and ground traces, ferrite beads)
Power switch (FET on-resistance)
Overcurrent sense device.
PCB resistance and power supply connector resistance may cause a drop of 25 mV,
leaving only 75 mV as the voltage drop allowed across the power switch and
overcurrent sense device. The individual voltage drop components are shown in
Figure 7
.
(1) Includes PCB traces, ferrite beads, etc.
Fig 7.
Typical voltage drop components in self-powered mode using individual overcurrent detection.
handbook, full pagewidth
5 V
POWER SUPPLY
±
3% regulated
+
4.85 V(min)
MBL088
low-ohmic
PMOS switch
ISP1123
power
switch
VBUS
D
+
D
GND
SHIELD
4.75 V(min)
downstream
port
connector
hub board
resistance
voltage drop
25 mV
voltage drop
75 mV
(1)
相關(guān)PDF資料
PDF描述
ISP1123D Universal Serial Bus compound hub
ISP1123NB Universal Serial Bus compound hub
ISP1130 Universal Serial Bus compound hub with integrated keyboard controller
ISP1130DL Universal Serial Bus compound hub with integrated keyboard controller
ISP1130N Universal Serial Bus compound hub with integrated keyboard controller
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ISP1123BD 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Universal Serial Bus compound hub
ISP1123D 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Universal Serial Bus compound hub
ISP1123NB 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Universal Serial Bus compound hub
ISP1130 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Universal Serial Bus compound hub with integrated keyboard controller
ISP1130DL 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Universal Serial Bus compound hub with integrated keyboard controller
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