p82b715t NXP Semiconductors, p82b715t Datasheet - Page 4

• Manufacturer Part Number: p82b715t
• Description: I2c Bus Extender
• Manufacturer: NXP Semiconductors

Philips Semiconductors
FUNCTIONAL DESCRIPTION
The 82B715 bipolar integrated circuit contains two identical buffer
circuits which enable I
over long distances without degradation of system performance or
requiring the use of special cables.
The buffer has an effective current gain of ten from I
Buffered bus. Whatever current is flowing out of the I
ten times that current will be flowing into the Buffered bus side (see
Figure 2).
As a consequence of this amplification the system is able to drive
capacitive loads up to ten times the standard limit on the Buffered
bus side. This current based buffering approach preserves the
bi-directional, open-collector/open-drain characteristic of the I
SDA/SCL lines.
To minimize interference and ensure stability, current rise and fall
rates are internally controlled.
1998 Jan 09
I
2
C bus extender
I
S
2
X
C BUS
V
GND
CC
INTERFACE
STANDARD
2
SDA
SCL
C and similar bus systems to be extended
I
2
C
82B715
1/2
1/2
Figure 2. Equivalent Circuit: One Half 82B715
Figure 3. Minimum Sub-System with 82B715
2
2
V
V
C bus to
C bus side,
INTERFACE
CC
CC
BUFFERED
I
B
2
C
CABLE
LONG
4
LDA
LCL
INTERFACE
BUFFERED
CURRENT
APPLICATION NOTES
By using two (or more) 82B715 ICs, a sub-system can be built which
retains the interface characteristics of an I
be included in, or optionally added to, any I
The sub-system features a low impedance or “Buffered” bus,
capable of driving large wiring capacities (see Figure 3).
I
As with the standard I
aprovide the logic HIGH levels on the Buffered bus. (Standard
open-collector configuration of the I
these pull-up resistors depends on the system.
If the buffer is to be permanently connected into the system, the
circuit should be configured with only one pull-up resistor on the
Buffered bus and none on the I
Alternatively a buffer may be connected to an existing I
this case the Buffered bus pull-up will act in parallel with the I
pull-up.
SENSE
2
C Systems
82B715
1/2
1/2
INTERFACE
STANDARD
2
C system, pull-up resistors are required to
I
2
C
SDA
SCL
10 (I
2
C bus.
B
)
2
C bus). The size and number of
DEVICE
SU00293
BUFFERED BUS
L
I
2
X
2
C
C device so that it may
2
C or related system.
Preliminary specification
SU00292
82B715
2
C system. In
2
C bus