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Philips ISP1122 12.3 Tuning the overcurrent trip voltage, 12.4 Reference circuits

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Philips Semiconductors ISP1122

USB stand-alone hub

Product speciﬁcation Rev. 03 — 29 March 2000 25 of 48

9397 750 07002 © Philips Electronics N.V. 2000. All rights reserved.

The ISP1122 overcurrent detection circuit has been designed with a nominal trip

voltage (∆Vtrip) of 85 mV.This gives a typical trip current of approximately 850 mA for

a power switch with an on-resistance of 100 mΩ1.

12.3 Tuning the overcurrent trip voltage

The ISP1122 trip voltage can optionally be adjusted through external components to

set the desired trip current. This is done by inserting tuning resistors at pins SP/BP or

OCn (see Figure 9). Rtu tunes up the trip voltage ∆Vtrip and Rtd tunes it down

according to Equation 1.

(1)

with Iref(nom) =5µA and IOC(nom) = 0.5 µA.

12.4 Reference circuits

Some typical examples of port power switching and overcurrentdetection modes are

given in Figure 10 to Figure 13.

The RC circuit (47 kΩand 0.1 µF) around the PMOS switch provides for soft turn-on.

The series resistor connecting the SP/BP pin to VCC tunes up the overcurrent trip

voltage slightly (see Figure 9). In the schematic diagram the resistor separates the

net names for pins VCC and SP/BP. This allows an automatic router to use a wide

trace for VCC and a narrow trace to connect pin SP/BP.

1. The following PMOS power switches have been tested to work well with the ISP1122: Philips PHP109, Vishay Siliconix Si2301DS,

Fairchild FDN338P.

∆Vtrip ∆Vtrip intrinsic()

I

ref Rtu

⋅IOC Rtd

⋅–+=

Iref(nom)=5µA

I

OC(nom) = 0.5 µA

IOC(nom) = 0.5 µA

a. Self-powered mode. b. Bus-powered mode.

Fig 9. Tuning the overcurrent trip voltage.

handbook, halfpage

MBL042

VCC Iref

Rtu Rtd

low-ohmic

PMOS switch

VCC SP/BP

ISP1122

OCn

IOC

handbook, halfpage

MBL043

VBUS

Rtd

low-ohmic

PMOS switch

VCC SP/BP

ISP1122

OCn

IOC

Contents

Main ISP1122 Universal Serial Bus stand-alone hub Universal Serial Bus Specication Rev. 1.1 USB Specication Rev. 1.1 Rev. 03 29 March 2000 Product specication 3. Ordering information 4. Block diagram This is a conceptual block diagram and does not include each individual signal. th ISP1122 5. Pinning information 5.1 ISP1122D (SO32) and ISP1122NB (SDIP32) Fig 2. Pin conguration SO32. Fig 3. Pin conguration SDIP32. 5.1.2 Pin description 5.1.1 Pinning Page Page 5.2 ISP1122BD (LQFP32) 5.2.1 Pinning Fig 4. Pin conguration LQFP32. 5.2.2 Pin description ISP1122BD Page 6. Functional description 6.1 Analog transceivers USB Specication Rev. 1.1 6.2 Philips Serial Interface Engine (SIE) 6.3 Hub repeater USB Specication Rev. 1.1 6.4 End-of-frame timers 6.5 General and individual port controller 7. Modes of operation Philips Semiconductors ISP1122 8. Endpoint descriptions 8.1 Hub endpoint 0 (control) 8.2 Hub endpoint 1 (interrupt) Philips Semiconductors ISP1122 9. Host requests 9.1 Standard requests 9.2 Hub specic requests Page 9.3 Descriptors The ISP1122 hub controller supports the following standard USB descriptors: USB Specication Rev. 1.1 Page USB Specication Rev. 1.0 9.4 Hub responses Page 10. I2C-bus interface 10.1 Protocol C-bus and how to use it The I 10.2 Hardware connections 10.3 Data transfer Philips Semiconductors ISP1122 11. Hub power modes USB Specication Rev.1.1 11.1 Voltage drop requirements 12. Overcurrent detection 12.1 Overcurrent circuit description 12.2 Power switch selection 12.3 Tuning the overcurrent trip voltage 12.4 Reference circuits Power switches 1 to 5 are low-ohmic PMOS devices as specied inSection 12.2. ISP1122 Fig 10. Mode 5: self-powered hub; individual port power switching; individual overcurrent detection. Power switch is low-ohmic PMOS device as specied inSection 12.2. Fig 11. Mode 1: self-powered hub; ganged port power switching; global overcurrent detection. Power switches 1 to 4 are low-ohmic PMOS devices as specied inSection 12.2. Fig 12. Mode 4: bus-powered hub; individual port power switching; individual overcurrent detection. Product specication Rev. 03 29 March 2000 29 of 48 Power switch is low-ohmic PMOS device as specied inSection 12.2. Fig 13. Mode 0: bus-powered hub; ganged port power switching; global overcurrent detection. 13. Limiting values In accordance with the Absolute Maximum Rating System (IEC 60134). 14. Static characteristics 15. Dynamic characteristics =0V;T on D = 1.5 k C; C = 50 pF; R =0V;T on D = 1.5 k C; C = 50 pF; R Fig 15. Source differential data jitter. Fig 16. Source differential data-to-EOP transition skew and EOP width. Fig 17. Receiver differential data jitter. Fig 18. Receiver SE0 width tolerance. Fig 19. Hub differential data delay and SOP distortion. [1] fSCL =164fXTAL. [2] Rise time is determined by Cb and pull-up resistor value Rp (typ. 4.7 k). Fig 20. Hub EOP delay and EOP skew. DD SS IH IL 16. Test information Fig 22. Load impedance for D+ and D- pins. Fig 21. I2C-bus timing. 17. Package outline Fig 23. SO32 package outline. SO32: plastic small outline package; 32 leads; body width 7.5 mm SOT287-1 SDIP32: plastic shrink dual in-line package; 32 leads (400 mil) SOT232-1 Fig 24. SDIP32 package outline. LQFP32: plastic low profile quad flat package; 32 leads; body 7 x 7 x 1.4 mm SOT358-1 Fig 25. LQFP32 package outline. c 18. Soldering 18.1 Introduction Data Handbook IC26; Integrated Circuit Packages 18.2 Surface mount packages 18.3 Through-hole mount packages 18.4 Package related soldering information 19. Revision history 20. Data sheet status 21. Denitions 22. Disclaimers 23. Licenses 24. Trademarks Philips Semiconductors - a worldwide company Internet: http://www.semiconductors.philips.com Contents