ISP1122ABD datasheet(22/48 Pages) PHILIPS

22 / 48 page

Philips Semiconductors

ISP1122A

USB stand-alone hub

Preliminary speciﬁcation

Rev. 01 — 27 March 2000

22 of 48

9397 750 06986

[1]

Default value at reset if no external EEPROM is present.

[2]

Modiﬁes the Hub Descriptor ﬁeld ‘bPwrOn2PwrGood’, see Table 14.

[3]

Modiﬁes the Hub Descriptor ﬁeld ‘MaxPower’, see Table 14.

11. 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 (VBUS) 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 ISP1122A supports

both modes, which can be selected using input INDV (see Table 4).

11.1 Voltage drop requirements

11.1.1

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.

Table 23: Conﬁguration bits

Bit

Function

Value

(Bin)

Description

OPTION

see Table 4 “Mode selection”

INDV

see Table 4 “Mode selection”

reserved

0 [1]

must always be programmed to logic 0

PwrOn2PwrGood [2]

0 [1]

100 ms (bPwrOn2PwrGood = 32H)

500 ms (bPwrOn2PwrGood = FAH)

string descriptor enable

0 [1]

string descriptors disabled

string descriptors enabled (strings:

“Philips Semiconductors”, “ISP1122A”)

internal analog overcurrent

detection enable

internal analog overcurrent detection

circuit disabled; overcurrent pins OCn

function as digital inputs (TTL level)

1 [1]

internal analog overcurrent detection

circuit enabled

C7, C6

MaxPower [3]

00 [1]

100 mA (MaxPower = 32H)

500 mA (MaxPower = FAH)

0 mA (MaxPower = 00H)

ISP1122ABD 数据表(PDF) 22 Page - NXP Semiconductors

ISP1122ABD 数据表(HTML) 22 Page - NXP Semiconductors

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

数据表下载

链接网址

ISP1122ABD 数据表(PDF) 22 Page - NXP Semiconductors

ISP1122ABD 数据表(HTML) 22 Page - NXP Semiconductors

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

数据表 下载

链接网址

数据表下载