82B715 PHILIPS
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/C0109 /C0110 /C0114 82B715 I2C bus extender Preliminary specification Supesedes data of 1997 Apr 07 IC20 Data Handbook
1998 Jan 09
Philips Semiconductors Preliminary specification 82B715I2C bus extender
21998 Jan 09
DESCRIPTION
The 82B715 is a bipolar integrated circuit intended for application in I2C bus systems. While retaining all the operating modes and features of the I2C system it permits extension of the practical separation distance between components on the I2C bus by buffering both the data (SDA) and the clock (SCL) lines. The I2C bus capacitance limit of 400pF restricts practical communication distances to a few meters. Using one 82B715 at each end of longer cables reduces the cable loading capacitance on the I2C bus by a factor of 10 times and may allow the use of low cost general purpose wiring to extend bus lengths.
FEATURES
- Dual, bi-directional, unity voltage gain buffer
- I2C bus compatible
- Logic signal levels may include both supply and ground
- X10 impedance transformation
- Wide supply voltage range PIN CONFIGURATIONS N.C. GND SX LY SY N.C.5
8 VCC
1 N.C.
2 LX Buffered Bus, LDA or LCL
3 SX I2C Bus, SDA or SCL
4 GND Negative Supply
5 N.C.
6 SY I2C Bus, SCL or SDA
7 LY Buffered Bus, LCL or LDA
8 VCC Positive Supply
SYMBOL PARAMETER MIN. TYP. MAX. UNIT VCC Supply voltage 4.5 12 V ICC Quiescent current 16 mA Iline Output sink capability 30 mA Vin Input voltage range 0 VCC V Vout Output voltage range 0 VCC V Zin/Zout Impedance transformation 8 10 13 Tamb Temperature range –40 +85 °C
ORDERING INFORMATION
DESCRIPTION ORDER CODE DRAWING NUMBER 8-pin plastic dual In-line package P82B715P N SOT97-1 8-pin plastic small outline package P82B715T D SOT96-1 NOTE: 1. For applications requiring, 3V operation and additional buffer performance, see P82B96 Data Sheet.
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Figure 1. Block Diagram: 82B715
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requiring the use of special cables. rates are internally controlled. be included in, or optionally added to, any I2C or related system. capable of driving large wiring capacities (see Figure 3). these pull-up resistors depends on the system. Figure 2. Equivalent Circuit: One Half 82B715 Figure 3. Minimum Sub-System with 82B715
Philips Semiconductors Preliminary specification 82B715I2C bus extender
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Limiting values in accordance with the Absolute Maximum System (IEC 134). Voltages with respect to pin GND (DIL-8 pin 4). LIMITS SYMBOL PARAMETER MIN. MAX. UNIT VCC to GND Supply voltage range VCC –0.3 +12 V Vbus Voltage range I2C Bus, SCL or SDA 0 VCC V Vbuff Voltage range Buffered Bus 0 VCC V I DC current (any pin) 60 mA Ptot Power dissipation 300 mW Tstg Storage temperature range –55 +125 °C Tamb Operating ambient temperature range –40 +85 °C CHARACTERISTICS At Tamb = +25°C and VCC = 5 Volts, unless otherwise specified. LIMITS SYMBOL PARAMETER MIN. TYP. MAX. UNIT Power Supply VCC Supply voltage (operating) 4.5 — 12 V ICC Supply current — 16 — mA ICC Supply current at VCC = 12V — 22 — mA ICC Supply current, both I2C inputs LOW, both buffered outputs sinking 30mA. — 28 — mA Drive Currents ISx, ISy Output sink on I2C bus VSx, VSy LOW = 0.4V VLx, VLy LOW on Buffered bus = 0.3V 3 — — mA ILx, ILy Output sink on Buffered bus VLx, VLy LOW = 0.4V VSx, VSy LOW on I2C bus = 0.3V 30 — — mA Input Currents ISx, ISy Input current from I2C bus when ILx, ILy sink on Buffered bus = 30mA — — 3 mA ILx, ILy Input current from Buffered bus when ISx, ISy sink on I2C bus = 3mA — — 3 mA ILx, ILy Leakage current on Buffered bus VLx, VLy = VCC , and VSx, VSy = VCC — — 200 µA Impedance Transformation Zin/Zout Input/Output impedance 8 10 13 Pull-Up Resistance Calculation In calculating the pull-up resistance values, the gain of the buffer introduces scaling factors which must be applied to the system components. Viewing the system from the Buffered bus, all I 2C bus capacitances have effectively 10 times their I2C bus value. In practical systems the pull-up resistance is determined by the rise time limit for I2C systems. As an approximation this limit will be satisfied if the time constant (product of the net resistance and net capacitance) of the total system is set to 1 microsecond. The total time constant may either be set by considering each bus node individually (i.e., the I2C nodes, and the Buffered bus node) and choosing pull-up resistors to give time constants of 1 microsecond for each node; or by combining the capacitances into an equivalent capacitive loading on the Buffered bus, and calculating the Buffered bus pull-up resistor required by this equivalent capacitance. For each separate bus the pull-up resistor may be calculated as follows: R 1 sec C deviceC wiring Where: Cdevice = sum of device capacitances connected to each bus, and Cwiring = total wiring and stray capacitance on each bus. If these capacitances are not known then a good approximation is to assume that each device presents 10pF of load capacitance and 10pF of wiring capacitance.
Philips Semiconductors Preliminary specification 82B715I2C bus extender
1998 Jan 09 6
The capacitance figures for one or more individual I2C bus nodes should be multiplied by a factor of 10 times, and then added to the Buffered bus capacitance. Calculation of a new Buffered bus pull-up resistor will alllow this single pull-up resistor to act for both the included I 2C bus nodes and the Buffered bus. Thus it is possible to combine some or all of these separate pull-up resistors into a single resistor on the Buffered bus (the value of which is calculated from the sum of the scaled capacitances on the Buffered bus). If the buffer is to be permanently connected into the system then all the separate pull-up resistors should be combined. But if it is to be connected by adding it onto an existing system, then only those on the additional I 2C bus system can be combined onto the Buffered bus if the original system is required to be able to still operate on a stand-alone basis. A further restriction is that the maximum pull-up current, with the bus LOW, should not exceed the I2C bus specification maximum of 3mA, or 30mA on the Buffered bus. The following formula applies: 30mA /C0117 V CC /C00420.4 R P Where: RP = scaled parallel combination of all pull-up resistors. If this condition is met, the fall time specifications will also be met. Figure 4 shows typical loading calculations for the expanded I2C bus. Sx, Sy, I2C Bus, SDA or SCL Because the two buffer circuits in the 82B715 are identical either input pin can be used as the I 2C Bus SDA data line, or the SCL clock line. Lx, Ly, Buffered Bus, LDA or LCL On the buffered low impedance line side, the corresponding output becomes LDA and LCL. VCC , GND — Positive and Negative Supply Pins In normal use the power supply voltages at each end of the low impedance line should be comparable. If these differ by a significant amount, noise margin is sacrificed.
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values and combined the node and cable capacitances. Figure 4. Typical Loading Calculation: I2C Bus with 82B715
Philips Semiconductors Preliminary specification 82B715I2C bus extender
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DIP8: plastic dual in-line package; 8 leads (300 mil) SOT97-1
Philips Semiconductors Preliminary specification 82B715I2C bus extender
1998 Jan 09 9
SO8: plastic small outline package; 8 leads; body width 3.9mm SOT96-1
Philips Semiconductors Preliminary specification 82B715I2C bus extender
1998 Jan 09 10
Short-form specification — The data in a short-form specification is extracted from a full data sheet with the same type number and title. For detailed information see the relevant data sheet or data handbook. Limiting values definition — Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one or more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or at any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended periods may affect device reliability. Application information — Applications that are described herein for any of these products are for illustrative purposes only. Philips Semiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing or modification. Disclaimers Life support — These products are not designed for use in life support appliances, devices or systems where malfunction of these products can reasonably be expected to result in personal injury. Philips Semiconductors customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify Philips Semiconductors for any damages resulting from such application. Right to make changes — Philips Semiconductors reserves the right to make changes, without notice, in the products, including circuits, standard cells, and/or software, described or contained herein in order to improve design and/or performance. Philips Semiconductors assumes no responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright, or mask work right to these products, and makes no representations or warranties that these products are free from patent, copyright, or mask work right infringement, unless otherwise specified. Philips Semiconductors
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P.O. Box 3409 Sunnyvale, California 94088–3409 Telephone 800-234-7381 Copyright Philips Electronics North America Corporation 1998 All rights reserved. Printed in U.S.A. Date of release: 06-98 Document order number: 9397 750 04049 /C0109 /C0110 /C0114 Data sheet status Objective specification Preliminary specification Product specification Product status Development Qualification Production Definition [1] This data sheet contains the design target or goal specifications for product development. Specification may change in any manner without notice. This data sheet contains preliminary data, and supplementary data will be published at a later date. Philips Semiconductors reserves the right to make chages at any time without notice in order to improve design and supply the best possible product. This data sheet contains final specifications. Philips Semiconductors reserves the right to make changes at any time without notice in order to improve design and supply the best possible product. Data sheet status [1] Please consult the most recently issued datasheet before initiating or completing a design.