ISL33001MSOPEVAL1Z

Application Note 1543
ISL33001MSOPEVAL1Z, ISL33002MSOPEVAL1Z,
ISL33003MSOPEVAL1Z Evaluation Board User’s Manual
Description
Evaluation Board
The ISL33001MSOPEVAL1Z, ISL33002MSOPEVAL1Z, and
ISL33003MSOPEVAL1Z evaluation board is designed to
provide a quick and easy method for evaluating the
ISL33001, ISL33002, ISL33003 2-Channel Bus Buffer.
It is recommended to understand the operation of the IC
for a complete utilization of the evaluation board. Refer
to the latest datasheet (FN7560) for the features and
operation of the ISL33001, ISL33002, ISL33003
2-Channel Bus Buffer. The evaluation board is developed
to evaluate the performance of the buffer used in a
typical application.
A picture of the main evaluation board is shown in
Figure 1. The ISL3300x MSOP package IC is soldered
onto the evaluation board and is designated as U1. A
typical application of the ISL3300x is an I2C bus buffer.
The evaluation board contains all the necessary
components to interface the buffer to an I2C bus.
Discrete NMOS transistors are used to produce the
pull-down functions of a wired-AND bus. Each SDA/SCL
pin on the buffer is connected to an external open-drain
NMOS transistor. The evaluation board also contains
connections for the bus pull-up resistor and load
capacitance. The logic input pins on the ISL3300x IC can
be held logic High by a pull-up resistor or driven
dynamically with an external logic source.
FIGURE 1. TOP VIEW
Board Architecture/Layout
Features
• Evaluation Board for ISL33001IUZ, ISL33002IUZ,
and ISL33003IUZ IC in MSOP Package
• +2.3V to +5.5V Supply Operation
• Configured to operate in I2C environment
• Two Channel Supply for Level Shifting Applications
(ISL33002 and ISL33003)
• On-Board Discrete NMOS Open-Drain Transistors
Connected to SDA/SCL Pins
• 3V Logic for NMOS Transistor Gate
• On-Board Discrete Bus Pull-Up Resistors and Load
Capacitance on SDA/SCL Pins
• Convenient Test Points on SDA/SCL pins
Basic Layout of Evaluation Board
The basic layout of the main board is as follows (refer to
Figure 1):
1. VCC1, VCC2 and GND connections are at the top of
the board. The board operates on a +2.3V to +5.5V
power supply.
2. Input connections for the logic control pins are
available through BNC connectors or banana jacks.
3. The ISL3300x buffer is located at the center of the
board designated as U1.
4. Pull-up resistors and bus capacitance connections to
the SDA/SCL pins are available to the right and left
of U1.
5. U2 and U3 are the NMOS Open-Drain MOSFETs
connected to the SDA/SCL pins of the ISL3300x
buffer. The gate and drain of the MOSFETs are
brought out to BNC connectors.
April 1, 2010
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CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Application Note 1543
ISL3300x Buffers
ISL33002
The ISL33001, ISL33002, ISL33003 family of 2-Channel
Bus Buffers are designed to isolate the bus capacitance
and improve the rise time performance of heavily loaded
buses. The family of buffers offer +2.3V to +5.5V
operation, hot swap capability, transient rise time
accelerators, low power shutdown (ISL33001 and
ISL33003) and level shifting capability (ISL33002 and
ISL33003).
The ISL33002 device contains a level shifting supply
voltage VCC2 and an Accelerator disable pin ACC.
The buffers are designed to operate in wired-AND
environments such as I2C bus, supporting 400kHz Fast
Mode operation while being capable of driving the I2C
specified maximum capacitive loads of 400pF on the bus.
Power Supply
The ISL3300xMSOPEVAL1Z boards required a +2.3V to
+5.5V supply voltage to power the ISL3300x IC. For
ISL33002 and ISL33003 with level shifting power
supplies, a supply voltage in the +2.3V to +5.5V must be
connected to the VCC1 and VCC2 banana jack
connections. The evaluation board contains 0.01µF local
decoupling capacitor near the supply pins of the
ISL3300x IC.
Note: Jumper J4 connects either banana jack EN/VCC2 or
BNC connector EN/VCC2 to pin 1 of the ISL3300x IC.
When the jumper is in the 1-2 position the connection is
made to the banana jack. When in the 2-3 position the
connection is made to the BNC connector.
Logic Control Inputs
ISL33001
The ISL33001 device contains an enable logic input pin
“EN” and a logic output pin “READY”.
The enable pin connection can be made at the banana
jack or BNC connector. When the EN pin is driven high,
the part is enabled and the buffer will be connected once
it enters a valid state. When the EN pin is driven low, the
part is disabled, the IC draws low ICC current and any
signals on one side of the buffer will not appear on the
other side of the buffer.
Note: Jumper J4 connects either banana jack EN/VCC2 or
BNC connector EN/VCC2 to pin 1 (EN) of the ISL33001
IC. When the jumper is in the 1-2 position the connection
is made to the banana jack. When in the 2-3 position the
connection is made to the BNC connector.
The READY pin is an Open-Drain logic output pin on the
ISL33001 IC. The evaluation board gives the option to
connect the READY pin to a 10kΩ pull-up resistor to VCC1
or to an external connector.
Note: Jumper J21 connects either the 10kΩ pull-up
resistor or the external connector to pin 4 (READY) on
the ISL33001 IC. When J21 is in the 1-2 position the
READY pin is connected to the 10kΩ pull-up resistor.
When J21 is in the 2-3 position the READY pin is
connected commonly to banana jack EN/READY/ACC and
BNC connector JEN/READY/ACC.
2
The VCC2 connection can be made at the banana jack
EN/VCC2. For the ISL33002 IC, the threshold voltages on
the SDA_OUT and SCL_OUT pins are referred to the
VCC2 supply.
Note: Jumper J4 connects either banana jack EN/VCC2 or
BNC connector EN/VCC2 to pin 1 (VCC2) of the ISL33002
IC. When the jumper is in the 1-2 position the connection
is made to the banana jack. When in the 2-3 position the
connection is made to the BNC connector.
Note: Jumper J2 connects the pull-up resistors on the
SDA_OUT and SCL_OUT pins to either the VCC1 or VCC2
supply. When J2 is in the 1-2 position the pull-up
resistors are connected to VCC2. When J2 is in the 2-3
position the pull-up resistors are connected to VCC2.
The ACC pin is a logic input pin that enables/disables the
bus accelerators on the ISL33002 IC SDA/SCL pins. The
evaluation board gives the option to connect the ACC pin
to a 10kΩ pull-up resistor to VCC1 to enabled the
accelerators at all times or to banana jack/BNC
connectors for external control.
Jumper J21 connects either the 10kΩ pull-up resistor or
the external connector to pin 4 (ACC) on the ISL33002
IC. When J21 is in the 1-2 position the ACC pin is
connected to the 10kΩ pull-up resistor. When J21 is in
the 2-3 position the ACC pin is connected commonly to
banana jack EN/READY/ACC and BNC connector
JEN/READY/ACC.
ISL33003
The ISL33003 device contains a level shifting supply
voltage VCC2 and an enable logic input pin EN.
The VCC2 connection can be made at the banana jack
EN/VCC2. For the ISL33003 IC, the threshold voltages on
the SDA_OUT and SCL_OUT pins are referred to the
VCC2 supply.
Note: Jumper J4 connects either banana jack EN/VCC2 or
BNC connector EN/VCC2 to pin 1 (VCC2) of the ISL33003
IC. When the jumper is in the 1-2 position the connection
is made to the banana jack. When in the 2-3 position the
connection is made to the BNC connector.
Note: Jumper J2 connects the pull-up resistors on the
SDA_OUT and SCL_OUT pins to either the VCC1 or
VCC2 supply. When J2 is in the 1-2 position the pull-up
resistors are connected to VCC2. When J2 is in the 2-3
position the pull-up resistors are connected to VCC2.
SDA/SCL Pins
To include the features to evaluate the ISL3300x buffers
on the evaluation board, the necessary components are
available to interface with a 2-Channel wired-AND bus
such as I2C.
The I2C bus utilizes an active pull-down circuit to drive a
low on the bus and a pull-up resistor to passively pull the
AN1543.0
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Application Note 1543
bus high. The pull-up resistance and the parasitic bus
capacitance on the SDA/SCL lines define the transient
performance and maximum data rate of the I2C bus.
On the ISL3300xMSOPEVAL1Z evaluation boards, the
SDA/SCL pins on the buffer are connected to an
open-drain NMOS transistor, pull-up resistors to the VCC
supply, and place holders for adding load capacitance.
Each SDA/SCL pin has three available pull-up resistor
values: 1kΩ, 2.7kΩ, and 10kΩ. These values are
commonly used for the pull-up resistance in I2C
applications. A two pin jumper on the pull-up resistors
(J5, J7, J15, J17) connects one of these resistors to the
associated SDA/SCL pin.
Each SDA/SCL pin has two place holders for capacitors
to increase the load capacitance to the buffer. The place
holders are always connected to the SDA/SCL pins on
the IC.
NMOS Open-Drain MOSFETs
In addition to the pull-up resistors and the place holders
for bus capacitors, each SDA/SCL pin is connected to the
drain terminal of an open-drain NMOS transistor. The
transistors emulate the I2C devices that are connected to
the ISL3300x buffer in a typical application.
The gates of the transistors require 3V logic levels and
can be interfaced through the BNC connectors on the
board (see Table 1 for the connections of the gate to the
associated SDA/SCL pin).
TABLE 1. MOSFET CONNECTIONS TO ISL3300x BUFFER
GATE
U2/U3
PIN #
DRAIN
U2/U3
PIN #
CLK_IN
U2-2
SCL_IN
U2-6
CLK_OUT
U3-2
SCL_OUT
U3-6
DAT_IN
U2-5
SDA_IN
U2-3
DAT_OUT
U3-5
SDA_OUT
U3-3
The connections from the NMOS drain to the SDA/SCL
pins can be disconnected by the jumpers J18 (SCL_OUT),
J10 (SCL_IN), J14 (SDA_OUT), and J13 (SDA_IN).
Disconnecting the SDA/SCL pins from the drain of the
transistor will isolate the SDA/SCL pin capacitance of the
buffer from the Drain-Source capacitance of the MOSFET.
The source of the MOSFETs are connected to GND.
through jumpers J11 and J12. The connection to GND
can be disconnected by removing these two jumpers.
The source potential can then be adjusted by connecting
a power supply voltage at the VSUB banana jack
connection. This will drive the external input LOW to the
buffer with an offset of VSUB. This feature is helpful when
evaluating the VOS performance of the I2C buffers.
Note: When the source voltage is raised above GND, the
gate voltage should be compensated to maintain VGS
≥3V. Raising the source potential without changing the
gate voltage will provide the gate to the NMOS with less
drive and potentially cause the system to operate
incorrectly.
TABLE 2. BOARD COMPONENT DEFINITIONS
DESIGNATOR
DESCRIPTION
U1
ISL33001, ISL33002, or ISL33003 8 Ld MSOP I2C Buffer IC
VCC
Banana jack connection VCC supply
EN/VCC2
Banana jack connection for EN pin (ISL33001) and VCC2 supply pin (ISL33002, ISL33003)
JEN/VCC2
BNC connection for EN pin (ISL33001) and VCC2 supply pin (ISL33002, ISL33003)
EN/READY/ACC
Banana jack connection for READY pin (ISL33001), ACC pin (ISL33002) and EN pin (ISL33003)
JEN/READY/ACC
BNC jack connection for READY pin (ISL33001), ACC pin (ISL33002) and EN pin (ISL33003)
SCL_OUT
BNC connection to SCL_OUT pin
CLK_OUT
BNC connection to MOSFET gate for driving SCL_OUT pin
SDA_OUT
BNC connection to SDA_OUT pin
CLK_IN
BNC connection to MOSFET gate for driving SCL_IN pin
SDA_IN
BNC connection to SDA_IN pin
DAT_OUT
BNC connection to MOSFET gate for driving SDA_OUT pin
SCL_IN
BNC connection to SCL_IN pin
DAT_IN
BNC connection to MOSFET gate for driving SDA_IN pin
U2/U3
ROHM SM6K2 4V Drive Nch+Nch MOSFET
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Application Note 1543
Evaluation Board (Top View)
Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the
reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding.
For information regarding Intersil Corporation and its products, see www.intersil.com
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