|
|
bus extender. P82B715 Datasheet |
|
|
|
P82B715
I2C-bus extender
Rev. 08 — 9 November 2009
Product data sheet
1. General description
The P82B715 is a bipolar IC intended for application in I2C-bus and derivative bus
systems. While retaining all the operating modes and features of the I2C-bus 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 400 pF restricts practical communication distances to a
few meters. Using one P82B715 at each end of a long cable (connecting Lx/Ly to Lx/Ly)
reduces that cable’s loading on the linked I2C-buses by a factor of 10 and allows the total
system capacitance load (all devices, cable, connectors, and traces or wires connected to
the I2C-bus) to be around 3000 pF while the loading on each I2C-bus on the Sx/Sy sides
remains below 400 pF. Longer cables or low-cost, general-purpose wiring may be used to
link I2C-bus based modules without degrading noise margins. Multiple P82B715s can be
connected together, linking their Lx/Ly ports, in a star or multi-point architecture as long as
the total capacitance of the system is less than about 3000 pF and each bus at an Sx/Sy
connection is well below 400 pF. This configuration, with the master and/or slave devices
attached to the Sx/Sy port of each P82B715, has full multi-master communication
capability. The P82B715 alone does not support voltage level translation, but it can be
simply implemented using low cost transistors when required. There is no restriction on
interconnecting the Sx/Sy I/Os, and, because the device output levels are always held
within 100 mV of input drive levels, P82B715 is compatible with bus buffers that use
voltage level offsets, e.g., PCA9511A, PCA9517, Sx/Sy side of P82B96.
The lower VOL level and ability to operate with any master, slave or bus buffer is the
primary advantage of the using the P82B715 for long distance buses at the disadvantage
of not isolating bus capacitance like the P82B96 or PCA9600 are able to do. The primary
disadvantage of the P82B96 and PCA9600 is that the static level offset needed to isolate
bus capacitance does not allow these devices to operate with other bus buffers with
special offset levels or with master/slaves that require a VIL lower than 0.8 V with noise
margin. A proven quick design-in point-to-point/multi-point circuit (Figure 9) is included in
Section 8.2 to allow rapid use of the P82B715 along with comparison waveforms so that
the designer can clearly see the trade-offs between the P82B715 and the
P82B96/PCA9600 and choose the type of device that is best for their application.
2. Features
I Dual, bidirectional, unity voltage gain buffer with no external directional control
required
I Compatible with I2C-bus and its derivatives SMBus, PMBus, DDC, etc.
I Logic signal levels may include (but not exceed) both supply and ground
I Logic signal input voltage levels are output without change and are independent of VCC
I ×10 impedance transformation, but does not change logic voltage levels
|
NXP Semiconductors
P82B715
I2C-bus extender
I Supply voltage range 3 V to 12 V
I Clock speeds to at least 100 kHz and 400 kHz when other system delays permit
I ESD protection exceeds 2500 V HBM per Mil. Std 883C-3015.7 and 400 V MM per
JESD22-A115 (I/Os have diodes to VCC and GND)
I Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA
3. Applications
I Increase the total connected capacitance of an I2C-bus system to around 3000 pF
I Drive I2C-bus signals over long cables to approximately 50 meters or 3000 pF
I Drives ×10 lower impedance bus wiring for improved noise immunity
I Multi-drop distribution of I2C-bus signals using low cost twisted-pair cables
I AdvancedTCA radial IPMB architecture
I Driving 30 mA Fm+ devices from standard 3 mA parts
4. Ordering information
Table 1. Ordering information[1]
Type number Package
Name Description
Version
P82B715PN DIP8 plastic dual in-line package; 8 leads (300 mil)
SOT97-1
P82B715TD SO8 plastic small outline package; 8 leads; body width 3.9 mm SOT96-1
[1] For applications requiring lower voltage operation, or additional buffer performance, see application notes
AN255, “I2C/SMBus repeaters, hubs and expanders” and AN10710, “Features and applications of the
P82B715 I2C-bus extender”.
4.1 Ordering options
Table 2. Ordering options
Type number Topside mark
P82B715PN
P82B715PN
P82B715TD
P82B715
Temperature range
−40 °C to +85 °C
−40 °C to +85 °C
P82B715_8
Product data sheet
Rev. 08 — 9 November 2009
© NXP B.V. 2009. All rights reserved.
2 of 23
|
NXP Semiconductors
5. Block diagram
P82B715
I2C-bus extender
P82B715
SDA
VCC
BUFFER
LDA
SCL
BUFFER
Fig 1. Block diagram of P82B715
6. Pinning information
6.1 Pinning
GND
LCL
002aad689
P82B715PN
n.c. 1
Lx 2
Sx 3
GND 4
8 VCC
7 Ly
6 Sy
5 n.c.
002aad686
Fig 2. Pin configuration for DIP8
P82B715TD
n.c. 1
Lx 2
Sx 3
GND 4
8 VCC
7 Ly
6 Sy
5 n.c.
002aad687
Fig 3. Pin configuration for SO8
6.2 Pin description
Table 3.
Symbol
n.c.
Lx
Sx
GND
n.c.
Sy
Ly
VCC
Pin description
Pin
1
2
3
4
5
6
7
8
Description
not connected
buffered bus, LDA or LCL
I2C-bus, SDA or SCL
negative supply
not connected
I2C-bus, SCL or SDA
buffered bus, LCL or LDA
positive supply
P82B715_8
Product data sheet
Rev. 08 — 9 November 2009
© NXP B.V. 2009. All rights reserved.
3 of 23
|
| @ 2014 :: Datasheetspdf.com :: Semiconductors datasheet search & download site (Privacy Policy & Contact) |