Philips ISP1521 User Manual

ISP1521

Hi-Speed Universal Serial Bus hub controller

Rev. 03 — 24 November 2004 Product data

1. General description

The ISP1521 is a stand-alone Universal Serial Bus (USB) hub controller IC that complies with high-speed (480 Mbit/s), full-speed (12 Mbit/s) and low-speed (1.5 Mbit/s).

The upstream facing port can be connected to a Hi-Speed USB host or hub or to an Original USB hostor hub. If the upstream facingport is connected to a Hi-Speed USB host or hub, then the ISP1521 will operate as a Hi-Speed USB hub. That is, it will support high-speed, full-speed and low-speed devices connected to its downstream facing ports. If the upstream facing port is connected to an Original USB host or hub, then the ISP1521 will operate as an Original USB hub. That is, high-speed devices that are connected to its downstream facing ports will operate in full-speed mode instead.

The ISP1521 is a full hardware USB hub controller. All Original USB devices connected to the downstream facing ports are handled using a single Transaction Translator (TT), when operating in a cross-version environment. This allows the whole 480 Mbit/s upstream bandwidth to be shared by all the Original USB devices on its downstream facing ports.

Universal Serial Bus Speciﬁcation Rev. 2.0

. It supports data transfer at

The ISP1521 has seven downstream facing ports. If not used, ports 3 to 7 can be disabled. The vendor ID, product ID and string descriptors on the hub are supplied by the internal ROM; they can also be supplied by an external I2C-bus™ EEPROM or a microcontroller.

The ISP1521 is suitable for self-powered hub designs. An analog overcurrent detection circuitry is built into the ISP1521, which can also

accept digital overcurrent signals from external circuits; for example, Micrel MOSFET switch MIC2026. The circuitry can be conﬁgured to trip on a global or an individual overcurrent condition.

Each port comes with two status indicator LEDs. Target applications of the ISP1521 are monitor hubs, docking stations for notebooks,

internal USB hub for motherboards, hub for extending Intel® Easy PCs, hub boxes, and so on.

Philips Semiconductors

2. Features

■ Complies with:

■ Supports data transfer at high-speed (480 Mbit/s), full-speed (12 Mbit/s) and

■ Self-powered capability

■ USB suspend mode support

■ Conﬁgurable number of ports

■ Internal power-on reset and low voltage reset circuit

■ Port status indicators

■ Integrates high performance USB interface device with hub handler, Philips Serial

■ Built-in overcurrent detection circuit

■ Individual or ganged power switching, individual or global overcurrent protection,

■ Simple I2C-bus (master/slave) interface to read device descriptor parameters,

■ Visual USB trafﬁc monitoring (GoodLink™) for the upstream facing port

■ Uses 12 MHz crystal oscillator with on-chip Phase-Locked Loop (PLL) for low

■ Supports temperature range from −40 °C to +70 °C

■ Available in LQFP80 package.

ISP1521

Hi-Speed USB hub controller

◆

Universal Serial Bus Speciﬁcation Rev. 2.0

◆ Advanced Conﬁguration and Power Interface (ACPI™), OnNow™ and USB

power management requirements

low-speed (1.5 Mbit/s)

Interface Engine (SIE) and transceivers

and non-removable port support by I/O pins conﬁguration

language ID, manufacturer ID, product ID, serial number ID and string descriptors from a dedicated external EEPROM, or to allow the microcontroller to set up hub descriptors

ElectroMagnetic Interference (EMI)

3. Applications

■ Monitor hubs

■ Docking stations for notebooks

■ Internal hub for USB motherboards

■ Hub for extending Easy PCs

■ Hub boxes.

9397 750 13702

Product data Rev. 03 — 24 November 2004 2 of 53

Philips Semiconductors

4. Abbreviations

ACPI — Advanced Conﬁguration and Power Interface EMI — ElectroMagnetic Interference ESD — ElectroStatic Discharge NAK — Not AcKnowledge PID — Packet IDentiﬁer PLL — phase-Locked Loop SIE — Serial Interface Engine TT — Transaction Translator USB — Universal Serial Bus.

5. Ordering information

Table 1: Ordering information

Type number Package

ISP1521BE LQFP80 plastic low proﬁle quad ﬂat package; 80 leads; body

ISP1521

Hi-Speed USB hub controller

Name Description Version

SOT315-1

12 × 12 × 1.4 mm

9397 750 13702

Product data Rev. 03 — 24 November 2004 3 of 53

9397 750 13702

Product data Rev. 03 — 24 November 2004 4 of 53

xxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx x xxxxxxxxxxxxxx xxxxxxxxxx xxx xxxxxx xxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxxx xx xxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxx xxxxxxx xxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxx xxxxxx xx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxx xxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxx xxxxx x x

6. Block diagram

Philips Semiconductors

upstream port 0

RREF

RPU DM0 DP0

CC1 CC2 CC3 CC4

GND

11, 50 17, 56 30, 70 13, 52

2, 6, 8, 12, 14, 18, 29, 44, 47, 51, 53, 57, 71

31, 69

TRANSCEIVER

• ORIGINAL USB

• HI-SPEED USB

TRANSACTION

TRANSLATOR

CONTROLLER

ANALOG

PHILIPS PIE

MINI-HOST

PORT 1 PORT 2 to 6 PORT 7

POWER SWITCH

OVERCURRENT

DETECTION

LINK LEDS LINK LEDS

ANALOG TRANSCEIVER

• ORIGINAL USB

• HI-SPEED USB

HUB REPEATER

• ORIGINAL USB

• HI-SPEED USB

ROUTING LOGIC

V V V V

REF(5V0)

12 MHz

XTAL1 XTAL2

43424375

PLL

BIT CLOCK

RECOVERY

PHILIPS SIE

ISP1521

ANALOG

TRANSCEIVER

• ORIGINAL USB

• HI-SPEED USB

RAM ROM

I2C-BUS

CONTROLLER

HUB

CONTROLLER

PORT

CONTROLLER

POWER SWITCH

OVERCURRENT

DETECTION

80 79

41 60

C-bus SDA SCL

RESET_N

HUBGL_N

SUSPEND

ADOC NOOC

Hi-Speed USB hub controller

DM1 DP1

Fig 1. Block diagram.

19 20 23 24 72 73 48 49 36 37 65 66

OC1_N

downstream

port 1

PSW1_N

GRN1_N

AMB1_N

downstream

port 2 to port 6

DM7

DP7

downstream

OC7_N

port 7

PSW7_N

GRN7_N

AMB7_N

ISP1521

MLD710

Philips Semiconductors

7. Pinning information

7.1 Pinning

ISP1521

Hi-Speed USB hub controller

SUSPEND

GND

DM0

DP0

RPU

GND

RREF

GND

DM5

DP5

CC1

GND

CC4

GND

DM6

DP6

CC2

GND

DM1

DP1

SDA

SCL

HUBGL_N

AMB5_N

GRN5_N

AMB6_N

GRN6_N

AMB1_N

GRN1_N

1 2 3 4 5 6 7 8

9 10 11 12 13 14 15 16 17 18 19 20

ISP1521BE

GND

V 70

CC3VREF(5V0)

AMB2_N

GRN2_N

AMB7_N

GRN7_N

AMB3_N

GRN3_N

AMB4_N

GRN4_N 61

60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41

NOOC DP4 DM4 GND V

CC2

DP3 DM3 GND V

CC4

GND V

CC1

DP7 DM7 GND DP2 DM2 GND XTAL2 XTAL1 ADOC

MLD712

RESET_N

TEST_LOW

TEST_HIGH

OC1_N

OC6_N

PSW1_N

OC5_N

PSW6_N

GND

PSW5_N

CC3

OC4_N

REF(5V0)

OC3_N

PSW4_N

OC7_N

PSW3_N

OC2_N

PSW7_N

PSW2_N

Fig 2. Pin conﬁguration.

7.2 Pin description

Table 2: Pin description

Symbol

[2]

Pin Type Description

SUSPEND 1 O suspend indicator output; a HIGH level indicates that the hub is

GND 2 - ground supply DM0 3 AI/O upstream facing port 0 D− connection (analog)

9397 750 13702

Product data Rev. 03 — 24 November 2004 5 of 53

[1]

in the suspend mode

Philips Semiconductors

Table 2: Pin description

Symbol

DP0 4 AI/O upstream facing port 0 D+ connection (analog) RPU 5 AI pull-up resistor connection;connect this pin through a resistor of

GND 6 - ground supply RREF 7 AI referenceresistor connection; connect thispin through a resistor

GND 8 - ground supply DM5 9 AI/O downstream facing port 5 D− connection (analog) DP5 10 AI/O downstream facing port 5 D+ connection (analog) V

CC1

GND 12 - ground supply V

CC4

GND 14 - ground supply DM6 15 AI/O downstream facing port 6 D− connection (analog) DP6 16 AI/O downstream facing port 6 D+ connection (analog) V

CC2

GND 18 - ground supply DM1 19 AI/O downstream facing port 1 D− connection (analog) DP1 20 AI/O downstream facing port 1 D+ connection (analog) TEST_LOW 21 - connect to GND TEST_HIGH 22 - connect to 5.0 V through a 10 kΩ resistor OC1_N 23 AI/I overcurrent sense input for downstream facing port 1

PSW1_N 24 I/O output — power switch control output (open-drain) with an

OC6_N 25 AI/I overcurrent sense input for downstream facing port 6

PSW6_N 26 I/O output — power switch control output (open-drain) with an

OC5_N 27 AI/I overcurrent sense input for downstream facing port 5

PSW5_N 28 I/O output — power switch control output (open-drain) with an

GND 29 - ground supply V

CC3

REF(5V0)

Hi-Speed USB hub controller

[1]

…continued

[2]

Pin Type Description

1.5 kΩ±5 % to 3.3 V

of 12 kΩ±1 % to an analog band gap ground reference

11 - analog supply voltage 1 (3.3 V)

13 - crystal and PLL supply voltage 4 (3.3 V)

17 - transceiver supply voltage 2 (3.3 V)

(analog/digital)

internal pull-up resistor for downstream facing port 1 input — function of the pin when used as an input is given in

Table 5

(analog/digital)

internal pull-up resistor for downstream facing port 6 input — function of the pin when used as an input is given in

Table 5

(analog/digital)

internal pull-up resistor for downstream facing port 5 input — function of the pin when used as an input is given in

Table 5

30 - digital supply voltage 3 (3.3 V) 31 - reference voltage (5 V ± 5 %); used to power internal pull-up

resistors of PSWn_N pins and also for the analog overcurrent detection

ISP1521

[3] [3]

[4] [4]

9397 750 13702

Product data Rev. 03 — 24 November 2004 6 of 53

Philips Semiconductors

ISP1521

Hi-Speed USB hub controller

Table 2: Pin description

Symbol

[2]

Pin Type Description

[1]

…continued

OC4_N 32 AI/I overcurrent sense input for downstream facing port 4

(analog/digital)

PSW4_N 33 I/O output — power switch control output (open-drain) with an

internal pull-up resistor for downstream facing port 4 input — function of the pin when used as an input is given in

Table 5

OC3_N 34 AI/I overcurrent sense input for downstream facing port 3

(analog/digital)

PSW3_N 35 I/O output — power switch control output (open-drain) with an

internal pull-up resistor for downstream facing port 3 input — function of the pin when used as an input is given in

Table 5

OC7_N 36 AI/I overcurrent sense input for downstream facing port 7

(analog/digital)

PSW7_N 37 I/O output — power switch control output (open-drain) with an

internal pull-up resistor for downstream facing port 7 input — function of the pin when used as an input is given in

Table 5

OC2_N 38 AI/I overcurrent sense input for downstream facing port 2

(analog/digital)

PSW2_N 39 I/O output — power switch control output (open-drain) with an

internal pull-up resistor for downstream facing port 2 input — function of the pin when used as an input is given in

Table 5

RESET_N 40 I asynchronous reset input; when reset is active, the internal

switch to the 1.5 kΩ external resistor is opened, and all pins DPn and DMn are three-state; it is recommended that you connect to V

through an RCcircuit; refer to theschematics in

BUS

ISP1521 Hub Demo Board User’s Guide

ADOC 41 I analog or digital overcurrent detect selection input; a LOW

selects digital mode and a HIGH (3.3 Vor 5.0 V) selects analog

mode XTAL1 42 I crystal oscillator input (12 MHz) XTAL2 43 O crystal oscillator output (12 MHz) GND 44 - ground supply DM2 45 AI/O downstream facing port 2 D− connection (analog) DP2 46 AI/O downstream facing port 2 D+ connection (analog)

[4] [4]

GND 47 - ground supply DM7 48 AI/O downstream facing port 7 D− connection (analog) DP7 49 AI/O downstream facing port 7 D+ connection (analog) V

CC1

50 - analog supply voltage 1 (3.3 V)

[3] [3]

GND 51 - ground supply V

CC4

52 - crystal and PLL supply voltage 4 (3.3 V) GND 53 - ground supply DM3 54 AI/O downstream facing port 3 D− connection (analog)

[3]

9397 750 13702

Product data Rev. 03 — 24 November 2004 7 of 53

Philips Semiconductors

ISP1521

Hi-Speed USB hub controller

Table 2: Pin description

Symbol

[2]

Pin Type Description

DP3 55 AI/O downstream facing port 3 D+ connection (analog) V

CC2

56 - transceiver supply voltage 2 (3.3 V)

[1]

…continued

[3]

GND 57 - ground supply DM4 58 AI/O downstream facing port 4 D− connection (analog) DP4 59 AI/O downstream facing port 4 D+ connection (analog)

[3] [3]

NOOC 60 I no overcurrent protection selection input; connect this pin to

HIGH (3.3 V) to select no overcurrent protection; if no overcurrent is selected, all OC_N pins must be connected to V

REF(5V0)

GRN4_N 61 I/O output — green LED port indicator (open-drain) for downstream

facing port 4 input — function of the pin when used as an input is given in

Table 9

AMB4_N 62 I/O output — amber LED port indicator (open-drain) for

downstream facing port 4 input — function of the pin when used as an input is given in

Table 8

GRN3_N 63 I/O output — green LED port indicator (open-drain) for downstream

facing port 3 input — function of the pin when used as an input is given in

Table 9

AMB3_N 64 I/O output — amber LED port indicator (open-drain) for

downstream facing port 3 input — function of the pin when used as an input is given in

Table 8

GRN7_N 65 I/O output — green LED port indicator (open-drain) for downstream

facing port 7 input — function of the pin when used as an input is given in

Table 9

AMB7_N 66 I/O output — amber LED port indicator (open-drain) for

downstream facing port 7 input — function of the pin when used as an input is given in

Table 8

GRN2_N 67 I/O output — green LED port indicator (open-drain) for downstream

facing port 2 input — function of the pin when used as an input is given in

Table 9

AMB2_N 68 I/O output — amber LED port indicator (open-drain) for

downstream facing port 2 input — function of the pin when used as an input is given in

Table 8

REF(5V0)

69 - reference voltage (5 V ± 5 %); used to power internal pull-up

resistors of PSWn_N pins and also for the analog overcurrent detection

CC3

70 - digital supply voltage 3 (3.3 V)

9397 750 13702

Product data Rev. 03 — 24 November 2004 8 of 53

Philips Semiconductors

Table 2: Pin description

Symbol

GND 71 - ground supply GRN1_N 72 I/O output — green LED port indicator (open-drain) for downstream

AMB1_N 73 I/O output — amber LED port indicator (open-drain) for

GRN6_N 74 I/O output — green LED port indicator (open-drain) for downstream

AMB6_N 75 I/O output — amber LED port indicator (open-drain) for

GRN5_N 76 I/O output — green LED port indicator (open-drain) for downstream

AMB5_N 77 I/O output — amber LED port indicator (open-drain) for

HUBGL_N 78 O hub GoodLink LED indicator output; the LED is off until the hub

SCL 79 I/O I SDA 80 I/O I

[2]

Pin Type Description

ISP1521

Hi-Speed USB hub controller

[1]

…continued

facing port 1 input — function of the pin when used as an input is given in

Table 9

downstream facing port 1 input — function of the pin when used as an input is given in

Table 8

facing port 6 input — function of the pin when used as an input is given in

Table 9

downstream facing port 6 input — function of the pin when used as an input is given in

Table 8

facing port 5 input — function of the pin when used as an input is given in

Table 9

downstream facing port 5 input — function of the pin when used as an input is given in

Table 8

is conﬁgured; a transaction between the host and the hub will blink the LED offfor100 ms; this LED isoff in thesuspend mode (open-drain)

C-bus clock (open-drain); see Table 11

C-bus data (open-drain); see Table 11

[1] The maximum current the ISP1521 can sink on a pin is 8 mA. [2] Symbol names ending with underscore N (for example, NAME_N) represent active LOW signals. [3] To disable a downstream port n, connect both pins DPn and DMn to VCC (3.3 V); unused ports must

be disabled in reverse order starting from port 7.

[4] Downstream ports 1 and 2 cannot be disabled.

9397 750 13702

Product data Rev. 03 — 24 November 2004 9 of 53

Philips Semiconductors

8. Functional description

8.1 Analog transceivers

The integrated transceivers directly interface to USB lines. They can transmit and receive serial data at high-speed (480 Mbit/s), full-speed (12 Mbit/s) and low-speed (1.5 Mbit/s).

8.2 Hub controller core

The main components of the hub core are:

• Philips Serial Interface Engine (SIE)

• Routing logic

• Transaction Translator (TT)

• Mini-host controller

• Hub repeater

• Hub controller

• Port controller

• Bit clock recovery.

ISP1521

Hi-Speed USB hub controller

8.2.1 Philips serial interface engine

The Philips SIE implements the full USB protocol layer. It is completely hardwired for speed and needs no ﬁrmware intervention. The functions of this block include: synchronization, pattern recognition, parallel or serial conversion, bit (de-)stufﬁng, CRC checking and generation, Packet IDentiﬁer veriﬁcation and generation, address recognition, and handshake evaluation and generation.

8.2.2 Routing logic

The routing logic directs signaling to the appropriate modules (mini-host controller, Original USB repeater and Hi-Speed USB repeater) according to the topology in which the hub is placed.

8.2.3 Transaction translator

The TT acts as a go-between mechanism that links devices operating in the Original USB mode and the Hi-Speed USB upstream mode. For the ‘IN’ direction, data is concatenated in TT buffers till the proper length is reached, before the host takes the transaction. In the reverse direction (OUT), the mini-host dispenses the data contained in TT buffers over a period that ﬁts into the Original USB bandwidth. This continues until all outgoing data is emptied. TT buffers are used only on split transactions.

8.2.4 Mini-host controller

The internal mini-host generates all the Original USB IN, OUT or SETUP tokens for the downstream facing ports, while the upstream facing port is in the high-speed mode. The responses from the Original USB devicesare collected in TT buffers, until the end of the complete split transaction clears the TT buffers.

9397 750 13702

Product data Rev. 03 — 24 November 2004 10 of 53

Philips Semiconductors

8.2.5 Hub repeater

A hub repeater is responsible for managing connectivity on a per packet basis. It implements packet signaling connectivity and resume connectivity. There are two repeaters in the ISP1521: a Hi-Speed USB repeater and an Original USB repeater. The only major difference between these two repeaters is the speed at which they operate. When the hub is connected to an Original USB system, it automatically switches itself to function as a pure Original USB hub.

8.2.6 Hub and port controllers

The hub controller provides status report. The port controller provides control for individual downstream facing port; it controls the port routing module. Any port status change will be reported to the host via the hub status change (interrupt) endpoint.

8.2.7 Bit clock recovery

The bit clock recovery circuit extracts the clock from the incoming USB data stream.

8.3 Phase-locked loop clock multiplier

A 12 MHz to 480 MHz clock multiplier PLL is integrated on-chip. This allows the use of low-cost 12 MHz crystals. The low crystal frequency also minimizes ElectroMagnetic Interference (EMI). No external components are required for the operation of the PLL.

ISP1521

Hi-Speed USB hub controller

8.4 I2C-bus controller

A simple serial I2C-bus interface is provided to transfer vendor ID, product ID and string descriptor from an external I2C-busEEPROM (for example,Philips PCF8582 or equivalent) or microcontroller. A master/slave I2C-bus protocol is implemented according to the timing requirements as mentioned in the I2C-bus standard speciﬁcations. The maximum data count during I2C-bus transfers for the ISP1521 is 256 bytes.

8.5 Overcurrent detection circuit

An overcurrent detection circuit is integrated on-chip. The main features of this circuit are: self reporting, automatic resetting, low-trip time and low cost. This circuit offers an easy solution at no extra hardware cost on the board.

8.6 GoodLink

Indication of a good USB connection is provided through GoodLink technology. An LED can be directly connected to pin HUBGL_N via an external 330 Ω resistor.

During enumeration, the LED blinks on momentarily. After successful conﬁguration, the LED blinks off for 100 ms upon each transaction.

This featureprovides a user-friendly indication of the status of the hub, the connected downstream devices and the USB trafﬁc. It is a useful diagnostics tool to isolate faulty USB equipment and helps to reduce ﬁeld support and hotline costs.

8.7 Power-on reset

The ISP1521 has an internal Power-On Reset (POR) circuit.

9397 750 13702

Product data Rev. 03 — 24 November 2004 11 of 53

Philips Semiconductors

The triggering voltage of the POR circuit is 2.03 V nominal. A POR is automatically generated when VCC goes below the trigger voltage for a duration longer than 1 µs.

ISP1521

Hi-Speed USB hub controller

POR

2.03 V

0 V

≤ 683 µs

004aaa388

At t1: clock is running and available.

Fig 3. Power-on reset timing.

POR

EXTERNAL CLOCK

Stable external clock is to be available at A.

Fig 4. External clock with respect to power-on reset.

004aaa365

9397 750 13702

Product data Rev. 03 — 24 November 2004 12 of 53

Philips Semiconductors

9. Conﬁguration selections

The ISP1521 is conﬁgured through I/O pins and, optionally, through an external I2C-bus,in which case the hub can updateits conﬁguration descriptors as amaster or as a slave.

Table 3 shows the conﬁguration parameters.

Table 3: Conﬁguration parameters

Mode and selection Option Conﬁguration method

Pin control Software control Control pin Reference Affected ﬁeld Reference

Numberof downstream facing ports

Power switching mode none

Overcurrent protection mode

Non-removable ports any port can be

Port indicator support no

2 ports 3 ports 4 ports 5 ports 6 ports 7 ports

ganged multiple ganged individual

none

[2]

global multiple ganged individual

non-removable

yes

DM1/DP1 to DM7/DP7

PSW1_N to PSW7_N

[1]

NOOC and OC1_N to OC7_N

AMBn_N see Section 9.1.4 wHubCharacteristics:

all GRNn_N see Section 9.1.5 wHubCharacteristics:

see Section 9.1.1 bNbrPorts0 see Table 22

see Section 9.1.2 wHubCharacteristics:

see Section 9.1.3 wHubCharacteristics:

ISP1521

Hi-Speed USB hub controller

see Table 22

bits D1 and D0 bPwrOn2PwrGood:

time interval

see Table 22

bits D4 and D3

see Table 22

bit D2 (compound hub) DeviceRemovable:

bit map

see Table 22

bit D7

[1] Multiple ganged power mode is reported as individual power mode; refer to the USB 2.0 speciﬁcation. [2] When the hub uses the global overcurrent protection mode,the overcurrentindication is throughthe wHubStatus ﬁeld bit 1(overcurrent)

and the corresponding change bit (overcurrent change).

9397 750 13702

Product data Rev. 03 — 24 November 2004 13 of 53

Philips Semiconductors

9.1 Conﬁguration through I/O pins

9.1.1 Number of downstream facing ports

To discount a physical downstream facing port, connect pins DP and DM of that downstream facing port to VCC (3.3 V) starting from the highest port number (7); see

Table 4.

The sum of physical ports conﬁgured is reﬂected in the bNbrPorts ﬁeld.

Table 4: Downstream facing port number pin conﬁguration

Number of physical downstream facing port

715kΩ

615kΩ

515kΩ

415kΩ

315kΩ

215kΩ

DM1/DP1 DM2/DP2 DM3/DP3 DM4/DP4 DM5/DP5 DM6/DP6 DM7/DP7

pull-down

15 kΩ pull-down

ISP1521

Hi-Speed USB hub controller

15 kΩ pull-down

9.1.2 Power switching

Power switching of downstream ports can be done individually or ganged, where all ports are simultaneously switchedwith onepower switch. TheISP1521 supports both modes, which can be selected using input PSWn_N; see Table 5.

Voltage drop requirements: 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 the:

• Power supply connector

• Hub PCB (power and ground traces, ferrite beads)

• Power switch (FET on-resistance)

• Overcurrent sense device.

The 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 5.

9397 750 13702

Product data Rev. 03 — 24 November 2004 14 of 53

Philips Semiconductors

For global overcurrent detection, an increased voltage drop is needed for the overcurrent sense device (in this case, a low-ohmic resistor). This can be realized by using a special power supply of 5.1 V ± 3 %, as shown in Figure 6.

The PCB resistance may cause a drop of 25 mV, which leaves 75 mV for the power switch and overcurrent sense device.

ISP1521

Hi-Speed USB hub controller

voltage drop

25 mV

hub board resistance

4.75 V (min)

(1)

BUS

D+ D− GND SHIELD

004aaa264

downstream

port

connector

5 V

POWER SUPPLY

± 3 % regulated

4.85 V (min)

−

voltage drop

75 mV

ISP1521

power switch

(PSWn_N)

low-ohmic

PMOS switch

(1) Includes PCB traces, ferrite beads, and so on.

Fig 5. Typical voltage drop components in the self-powered mode using individual overcurrent detection.

voltage drop

5.1 V KICK-UP

POWER SUPPLY

± 3 % regulated

4.95 V(min)

−

100 mV

low-ohmic

sense resistor

for overcurrent

detection

(1) Includes PCB traces, ferrite beads, and so on.

voltage drop

75 mV

ISP1521 power

switch

(PSWn_N)

low-ohmic

PMOS switch

voltage drop

25 mV

hub board resistance

4.75 V(min)

(1)

BUS

D+ D− GND SHIELD

004aaa265

downstream

port

connector

Fig 6. Typical voltage drop components in the self-powered mode using global overcurrent detection.

PSWn_N pins have integrated weak pull-up resistors inside the chip.

Table 5: Power switching mode: pin conﬁguration

Power switching mode PSW1_N PSW2_N PSW3_N PSW4_N PSW5_N PSW6_N PSW7_N

None ground ground ground ground ground ground ground Ganged internal

ground ground ground ground ground ground

pull-up

Individual internal

pull-up

internal pull-up

9.1.3 Overcurrent protection mode

The ISP1521 supports all overcurrent protection modes: none, global and individual. No overcurrent protection mode reporting is selected when pin NOOC = HIGH.

Global and individual overcurrent protectionmodes areselected usingpins PSWn_N, following the power switching modes selection scheme; seeTable 6.

For the 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

9397 750 13702

the analog overcurrent detection, the OC_N pins must be connected to V

REF(5V0)

Product data Rev. 03 — 24 November 2004 15 of 53

Philips Semiconductors

ISP1521

Hi-Speed USB hub controller

Table 6: Overcurrent protection mode pin conﬁguration

Power switching mode NOOC PSW1_N PSW2_N PSW3_N PSW4_N PSW5_N PSW6_N PSW7_N

None HIGH ground ground ground ground ground ground ground Global LOW internal

pull-up

Individual LOW internal

pull-up

ground ground ground ground ground ground

internal pull-up

Both analog and digital overcurrent modes are supported; see Table 7. For digital overcurrent detection, the normal digital TTL level is accepted on the

overcurrent input pins. For analog overcurrent detection, the threshold is given in the DC characteristics. In this 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: Overcurrent detection mode selection pin conﬁguration

Pin ADOC Mode selection Description

3.3 Vor 5.0 V analog threshold ∆V Ground digital normal digital TTL level

trip

9.1.4 Non-removable port

A non-removable port, by deﬁnition, is a port that is embedded inside the hub application box and is not externally accessible. The LED port indicators (pins AMBn_N) of such a port are not used. Therefore, the corresponding amber LED port indicators are disabled to signify that the port is non-removable; see Table 8.

More than one non-removable port can be speciﬁed by appropriately connecting the corresponding amber LED indicators. At least one port should, however, be left as a removable port.

The detection of any non-removable port sets the hub descriptor into a compound hub.

Table 8: Non-removable port pin conﬁguration

AMBn_N (n=1to7) Non-removable port

Ground non-removable Pull-up with amber LED removable

9.1.5 Port indicator support

The port indicator support can be disabled by grounding all green port indicators (all pins GRNn_N); see Table 9. This is a global feature. It is not possible to disable port indicators for only one port.

Table 9: Port indicator support: pin conﬁguration

GRN1_N to GRN7_N Port indicator support

Ground not supported LED pull-up green LED for at least one port supported

9397 750 13702

Product data Rev. 03 — 24 November 2004 16 of 53

+ 37 hidden pages