2.5 V/3.3 V, 2-Bit, Individual Control
Level Translator Bus Switch
ADG3243
FEATURES
225 ps Propagation Delay through the Switch
4.5 ⍀ Switch Connection between Ports
Data Rate 1.5 Gbps
2.5 V/3.3 V Supply Operation
Level Translation
3.3 V to 2.5 V
2.5 V to 1.8 V
Small Signal Bandwidth 710 MHz
8-Lead SOT-23 Package
APPLICATIONS
3.3 V to 2.5 V Voltage Translation
2.5 V to 1.8 V Voltage Translation
Bus Switching
Bus Isolation
Hot Swap
Hot Plug
Analog Switch Applications
GENERAL DESCRIPTION
The ADG3243 is a 2.5 V or 3.3 V, 2-bit, 2-port digital switch
with individual channel control. It is designed on a low voltage
CMOS process, which provides low power dissipation yet gives
high switching speed and very low on resistance. This allows the
inputs to be connected to the outputs without additional propagation delay or generating additional ground bounce noise.
The switches are enabled by means of the bus enable (BEx) input
signal. This digital switch allows a bidirectional signal to be
switched when ON. In the OFF condition, signal levels up to
the supplies are blocked.
This device is ideal for applications requiring level translation.
When operated from a 3.3 V supply, level translation from 3.3 V
inputs to 2.5 V outputs is allowed. Similarly, if the device is
operated from a 2.5 V supply and 2.5 V inputs are applied, the
device will translate the outputs to 1.8 V. This makes the device
suited to applications requiring level translation between different
supplies, such as converter to DSP/microcontroller interfacing.
FUNCTIONAL BLOCK DIAGRAM
A0
BE0
A1
BE1
PRODUCT HIGHLIGHTS
1. 3.3 V or 2.5 V supply operation.
2. Extremely low propagation delay through switch.
3. 4.5 Ω switches connect inputs to outputs.
4. Level/voltage translation.
5. Tiny SOT-23 package.
B0
B1
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.
A Port Off CapacitanceCA OFFf = 1 MHz3.5pF
B Port Off CapacitanceC
A, B Port On CapacitanceC
Control Input CapacitanceC
SWITCHING CHARACTERISTICS
Propagation Delay A to B or B to A, t
Propagation Delay Matching
Bus Enable Time BEx to A or B
Bus Disable Time BEx to A or B
Bus Enable Time BEx to A or B
Bus Disable Time BEx to A or B
3
5
6
6
6
6
Maximum Data RateV
Channel JitterV
OFFf = 1 MHz3.5pF
B
, CB ON f = 1 MHz7pF
PD
A
IN
4
t
, t
PHL
t
, t
PZH
t
, t
PHZ
t
, t
PZH
t
, t
PHZ
f = 1 MHz4pF
CL = 50 pF, VCC = 3 V225ps
PLH
VCC = 3.0 V to 3.6 V13.24.6ns
PZL
VCC = 3.0 V to 3.6 V134ns
PLZ
VCC = 2.3 V to 2.7 V134ns
PZL
VCC = 2.3 V to 2.7 V12.53.4ns
PLZ
= 3.3 V; VA/VB = 2 V1.5Gbps
CC
= 3.3 V; VA/VB = 2 V45ps p-p
CC
5ps
DIGITAL SWITCH
On ResistanceR
ON
VCC = 3 V, VA = 0 V, IBA = 8 mA4.58Ω
VCC = 3 V, VA = 1.7 V, IBA = 8 mA1228Ω
= 2.3 V, VA = 0 V, IBA = 8 mA59Ω
V
CC
= 2.3 V, VA = 1 V, IBA = 8 mA918Ω
V
On Resistance Matching⌬R
ON
CC
VCC = 3 V, VA = 0 V, IA = 8 mA0.10.5Ω
POWER REQUIREMENTS
V
CC
Quiescent Power Supply CurrentI
Increase in ICC per Input
NOTES
1
Temperature range is as follows: B Version: –40°C to +85°C.
2
Typical values are at 25°C, unless otherwise stated.
3
Guaranteed by design, not subject to production test.
4
The digital switch contributes no propagation delay other than the RC delay of the typical RON of the switch and the load capacitance when driven by an ideal voltage
source. Since the time constant is much smaller than the rise/fall times of typical driving signals, it adds very little propagation delay to the system. Propagation delay
of the digital switch when used in a system is determined by the driving circuit on the driving side of the switch and its interaction with the load on the driven side.
5
Propagation delay matching between channels is calculated from the on resistance matching and load capacitance of 50 pF.
6
See Timing Measurement Information section.
7
This current applies to the control pin BEx only. The A and B ports contribute no significant ac or dc currents as they transition.
Specifications subject to change without notice.
7
⌬I
CC
CC
Digital Inputs = 0 V or V
CC
VCC = 3.6 V, BE0 = 3.0 V, BE1 = VCC or GND0.158µA
2.33.6V
0.011µA
REV. 0–2–
Page 3
ADG3243
TOP VIEW
(Not to Scale)
8
7
6
5
1
2
3
4
ADG3243
GND
A1
BE0
B0
BE1
V
CC
A0
B1
ABSOLUTE MAXIMUM RATINGS*
(TA = 25°C, unless otherwise noted.)
VCC to GND . . . . . . . . . . . . . . . . . . . . . . . . . –0.5 V to +4.6 V
Digital Inputs to GND . . . . . . . . . . . . . . . . . –0.5 V to +4.6 V
DC Input Voltage . . . . . . . . . . . . . . . . . . . . . –0.5 V to +4.6 V
DC Output Current . . . . . . . . . . . . . . . . . 25 mA per Channel
IR Reflow, Peak Temperature (<20 sec) . . . . . . . . . . . . 235°C
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those listed in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability. Only one absolute
maximum rating may be applied at any one time.
PIN CONFIGURATION
8-Lead SOT-23
PIN FUNCTION DESCRIPTIONS
Pin No.MnemonicDescription
1BE0Bus Enable (Active Low)
2A0Port A0, Input or Output
3A1Port A1, Input or Output
4GNDGround Reference
5B1Port B1, Input or Output
6B0Port B0, Input or Output
7BE1Bus Enable (Active Low)
8VCCPositive Power Supply Voltage
Table I. Truth Table
BExFunction
LAx = Bx, 3.3 V to 2.5 V/2.5 V to 1.8 V Level Shifting
HDisconnect
ADG3243BRJ-R2–40°C to +85°CSOT-23 (Small Outline Transistor Package)RJ-8SFA
ADG3243BRJ-REEL–40°C to +85°CSOT-23 (Small Outline Transistor Package)RJ-8SFA
ADG3243BRJ-REEL7–40°C to +85°CSOT-23 (Small Outline Transistor Package)RJ-8SFA
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although the
ADG3243 features proprietary ESD protection circuitry, permanent damage may occur on devices
subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended
to avoid performance degradation or loss of functionality.
REV. 0
–3–
Page 4
ADG3243
TERMINOLOGY
V
CC
Positive Power Supply Voltage.
GNDGround (0 V) Reference.
V
INH
V
INL
I
I
I
OZ
I
OL
V
P
Minimum Input Voltage for Logic 1.
Maximum Input Voltage for Logic 0.
Input Leakage Current at the Control Inputs.
OFF State Leakage Current. It is the maximum leakage current at the switch pin in the OFF state.
ON State Leakage Current. It is the maximum leakage current at the switch pin in the ON state.
Maximum Pass Voltage. The maximum pass voltage relates to the clamped output voltage of an NMOS device when
the switch input voltage is equal to the supply voltage.
R
ON
Ohmic Resistance Offered by a Switch in the ON State. It is measured at a given voltage by forcing a specified
amount of current through the switch.
⌬R
ON
OFFOFF Switch Capacitance.
C
X
C
ONON Switch Capacitance.
X
C
IN
I
CC
ON Resistance Match between Any Two Channels, i.e., RON max – R
Control Input Capacitance. This consists of BEx.
Quiescent Power Supply Current. This current represents the leakage current between the VCC and ground pins.
ON
min.
It is measured when all control inputs are at a logic high or low level and the switches are OFF.
⌬I
t
t
PLH
PZH
CC
, t
, t
PHL
PZL
Extra power supply current component for the EN control input when the input is not driven at the supplies.
Data Propagation Delay through the Switch in the ON State. Propagation delay is related to the RC time constant
R
× CL, where CL is the load capacitance.
ON
Bus Enable Times. These are the times taken to cross the VT voltage at the switch output when the switch turns on
in response to the control signal, BEx.
t
PHZ
, t
PLZ
Bus Disable Times. This is the time taken to place the switch in the high impedance OFF state in response to the control
signal. It is measured as the time taken for the output voltage to change by V
from the original quiescent level,
⌬
with reference to the logic level transition at the control input. (Refer to Figure 3 for enable and disable times.)
Max Data RateMaximum Rate at which Data Can Be Passed through the Switch.
Channel JitterPeak-to-Peak Value of the Sum of the Deterministic and Random Jitter of the Switch Channel.
REV. 0–4–
Page 5
Typical Performance Characteristics–ADG3243
40
TA = 25ⴗC
35
30
)
25
⍀
(
ON
20
R
15
10
5
0
00.5
1.52.53.5
VA/VB (V
)
TPC 1. On Resistance vs.
Input Voltage
15
= 2.5V
V
CC
10
ⴙ85ⴗC
(⍀)
ON
R
5
ⴙ25ⴗC
VCC = 3V
VCC = 3.3V
VCC = 3.6V
3.02.01.0
ⴚ40ⴗC
40
TA = 25ⴗC
35
30
)
25
⍀
(
ON
20
R
15
10
5
0
00.5
1.52.5
VA/VB (V
)
TPC 2. On Resistance vs.
Input Voltage
3.0
TA = 25ⴗC
= –5A
I
O
2.5
2.0
(V)
1.5
OUT
V
1.0
0.5
VCC = 2.3V
VCC = 2.5V
= 2.7V
V
CC
VCC = 3.6V
V
CC
VCC = 3V
= 3.3V
20
= 3.3V
V
CC
15
(⍀)
10
ON
R
5
0
3.02.01.0
00.5
ⴙ85ⴗC
ⴚ40ⴗC
VA/VB (V)
ⴙ25ⴗC
1.5
2.01.0
TPC 3. On Resistance vs. Input
Voltage for Different Temperatures
2.5
TA = 25ⴗC
I
= –5A
O
2.0
1.5
(V)
OUT
V
1.0
0.5
VCC = 2.7V
VCC = 2.5V
VCC = 2.3V
0
00.5
VA/VB(V)
1.0
TPC 4. On Resistance vs. Input
Voltage for Different Temperatures
500
TA = 25ⴗC
450
400
350
300
250
(A)
CC
I
200
150
100
50
0
051015 20 25 30 35 40 45
ENABLE FREQUENCY (MHz)
VCC = 3.3V
VCC = 2.5V
TPC 7. ICC vs. Enable Frequency
1.2
0
00.5
TPC 5. Pass Voltage vs. V
3.0
2.5
2.0
(V)
1.5
OUT
V
1.0
0.5
50
0
1.02.03.0
1.52.53.5
VA/VB (V)
TA = 25ⴗC
V
= 0V
A
BEx = 0
VCC = 3.3V
0.020.040.060.080.100
CC
VCC = 2.5V
IO (A)
TPC 8. Output Low Characteristic
0
00.5
TPC 6. Pass Voltage vs. V
3.0
TA = 25ⴗC
V
= V
A
CC
BEx = 0
VCC = 2.5V
–0.08–0.06–0.04–0.020
(V)
V
OUT
2.5
2.0
1.5
1.0
0.5
0
–0.10
1.52.5
1.02.03.0
VA/VB (V)
CC
VCC = 3.3V
IO (A)
TPC 9. Output High Characteristic
REV. 0
–5–
Page 6
ADG3243
0
TA = 25ⴗC
–0.2
ON OFF
C
= InF
L
–0.4
–0.6
VCC = 2.5V
–0.8
(pC)
–1.0
INJ
Q
–1.2
–1.4
–1.6
–1.8
–2.0
00.5
VCC = 3.3V
1.52.5
1.02.03.0
VA/VB (V)
TPC 10. Charge Injection vs.
Source Voltage
0
TA = 25ⴗC
–10
= 3.3V/2.5V
V
CC
= 0dBm
V
IN
–20
N/W ANALYZER
= RS = 50⍀
R
L
–30
–40
–50
–60
ATTENUATION (dB)
–70
–80
–90
–100
0.11000110
:
FREQUENCY (MHz)
100
TPC 13. Off Isolation vs. Frequency
0
TA = 25ⴗC
–2
= 3.3V/2.5V
V
CC
= 0dBm
V
IN
–4
N/W ANALYZER
= RS = 50⍀
R
L
–6
–8
ATTENUATION (dB)
–10
–12
–14
0.03 0.11000
:
110100
FREQUENCY (MHz)
TPC 11. Bandwidth vs. Frequency
4.0
VCC = 3.3V
3.5
3.0
2.5
ENABLE
2.0
TIME (ns)
1.5
1.0
0.5
0
–40–200
TEMPERATURE (ⴗC)
ENABLE
DISABLE
VCC = 2.5V
DISABLE
20806040
TPC 14. Enable/Disable Time
vs. Temperature
0
TA = 25ⴗC
–10
V
= 3.3V/2.5V
CC
V
= 0dBm
–20
IN
N/W ANALYZER
–30
R
= RS = 50⍀
L
–40
–50
–60
–70
ATTENUATION (dB)
–80
–90
–100
0.03 0.11.0
101000100
FREQUENCY (MHz)
TPC 12. Crosstalk vs. Frequency
100
VCC = 3.3V
90
= 1.5V p-p
V
IN
20dB ATTENUATION
80
70
60
50
40
JITTER (ps p-p)
30
20
10
0
0.5
0.7 0.9 1.1 1.3 1.5 1.7 1.9
DATA RATE (Gbps)
TPC 15. Jitter vs. Data Rate;
PRBS 31
100
95
VCC = 3.3V
90
V
= 1.5V p-p
IN
20dB ATTENUATION
85
80
75
70
EYE WIDTH (%)
65
60
% EYE WIDTH = ((CLOCK PERIOD –
55
JITTER p-p)/CLOCK PERIOD) ⴛ 100%
50
0.5
DATA RATE (Gbps)
1.51.31.10.90.71.7 1.9
TPC 16. Eye Width vs. Data Rate;
PRBS 31
50mV/DIV
200ps/DIV
VCC = 3.3V
= 1.5V p-p
V
IN
20dB
ATTENUATION
T
= 25ⴗC
A
TPC 17. Eye Pattern; 1.5 Gbps,
= 3.3 V, PRBS 31
V
CC
20mV/DIV
200ps/DIV
V
= 2.5V
CC
V
= 1.5V p-p
IN
20dB
ATTENUATION
T
= 25ⴗC
A
TPC 18. Eye Pattern; 1.244 Gbps,
= 2.5 V, PRBS 31
V
CC
REV. 0–6–
Page 7
ADG3243
TIMING MEASUREMENT INFORMATION
For the following load circuit and waveforms, the notation that
is used is V
VVand VV or VV and VV
GENERATOR
NOTE S
PULSE GENERATOR FOR ALL PULSES:
FREQUENCY ⱕ 10MHz.
INCLUDES BOARD, STRAY, AND LOAD CAPACITANCES.
C
L
RT IS THE TERMINATION RESISTOR, SHOULD BE EQUAL TO Z
OF THE PULSE GENERATOR .
and V
IN
====
INAOUTBINBOUTA
PULSE
where
OUT
V
CC
R
OUT
L
R
L
DUT
t
ⱕ 2.5ns,
R
V
OUT
C
L
t
ⱕ 2.5ns,
F
V
IN
R
T
SW1
2 ⴛ V
GND
CC
Figure 1. Load Circuit
V
CONTROL
INPUT BEx
V
OUT
t
PLH
t
PLH
IH
V
T
0V
V
H
V
T
V
L
Figure 2. Propagation Delay
Test Conditions
SymbolVCC = 3.3 V ⴞ 0.3 VVCC = 2.5 V ⴞ 0.2 VUnit
R
L
V
⌬
C
L
V
T
500500Ω
300150mV
5030pF
1.50.9V
Table II. Switch Position
TestS1
CONTROL INPUT BEx
V
SW1 @ 2V
CC
SW1 @ GND
OUT
V
OUT
= 0V
V
IN
= V
V
IN
t
t
CC
PLZ
PHZ
, t
PZL
, t
PZH
ENABLE
t
PZL
t
PZH
2 × V
CC
GND
DISABLE
t
PLZ
V
CC
V
T
t
PHZ
V
T
0V
V
INH
V
T
0V
V
CC
VL + V
V
L
V
H
VH –V
0V
⌬
⌬
Figure 3. Enable and Disable Times
REV. 0
–7–
Page 8
ADG3243
V
IN
1.8V
V
OUT
0V
2.5V
SWITCH
INPU T
SWITCH
OUTPUT
2.5V SUPPLY
BUS SWITCH APPLICATIONS
Mixed Voltage Operation, Level Translation
Bus switches can provide an ideal solution for interfacing between
mixed voltage systems. The ADG3243 is suitable for applications where voltage translation from 3.3 V technology to a lower
voltage technology is needed. This device can translate from
2.5 V to 1.8 V or bidirectionally from 3.3 V directly to 2.5 V.
Figure 4 shows a block diagram of a typical application in which a
user needs to interface between a 3.3 V ADC and a 2.5 V microprocessor. The microprocessor may not have 3.3 V tolerant inputs,
therefore placing the ADG3243 between the two devices allows
the devices to communicate easily. The bus switch directly
connects the two blocks, thus introducing minimal propagation
delay, timing skew, or noise.
3.3V
3.3V ADC
3.3V
ADG3243
2.5V
2.5V
MICROPROCESSOR
Figure 4. Level Translation between a 3.3 V ADC
and a 2.5 V Microprocessor
3.3 V to 2.5 V Translation
When VCC is 3.3 V and the input signal range is 0 V to VCC, the
maximum output signal will be clamped to within a voltage
threshold below the V
3.3V
2.5V
supply.
CC
3.3V
2.5V
ADG3243
2.5V
2.5 V to 1.8 V Translation
When VCC is 2.5 V and the input signal range is 0 V to VCC, the
maximum output signal will, as before, be clamped to within a
voltage threshold below the V
supply. In this case, the output
CC
will be limited to approximately 1.8 V, as shown in Figure 8.
2.5V
2.5V
ADG3243
1.8V
Figure 7. 2.5 V to 1.8 V Voltage Translation
Figure 8. 2.5 V to 1.8 V Voltage Translation
Bus Isolation
A common requirement of bus architectures is low capacitance
loading of the bus. Such systems require bus bridge devices that
extend the number of loads on the bus without exceeding the
specifications. Because the ADG3243 is designed specifically for
applications that do not need drive yet require simple logic
functions, it solves this requirement. The device isolates access
to the bus, thus minimizing capacitance loading.
Figure 5. 3.3 V to 2.5 V Voltage Translation
In this case, the output will be limited to 2.5 V, as shown in
Figure 6. This device can be used for translation from 2.5 V to
3.3 V devices and also between two 3.3 V devices.
V
OUT
SWITCH
INPU T
3.3V SUPPLY
3.3V
V
IN
2.5V
SWITCH
OUTPUT
0V
Figure 6. 3.3 V to 2.5 V Voltage Translation
BUS SWITCH
LOCATION
LOAD A
LOAD B
LOAD C
LOAD D
BUS/
BACKPLANE
Figure 9. Location of Bus Switched in a Bus
Isolation Application
Hot Plug and Hot Swap Isolation
The ADG3243 is suitable for hot swap and hot plug applications.
The output signal of the ADG3243 is limited to a voltage that is
below the V
supply, as shown in Figures 6 and 8. Therefore
CC
the switch acts like a buffer to take the impact from hot insertion,
protecting vital and expensive chipsets from damage.
In hot plug applications, the system cannot be shut down when
new hardware is being added. To overcome this, a bus switch can
be positioned on the backplane between the bus devices and the
hot plug connectors. The bus switch is turned off during hot plug.
Figure 10 shows a typical example of this type of application.
REV. 0–8–
Page 9
CPU
RAM
BUS
ADG3243 ADG3243
PLUG-IN
CARD (1)
PLUG-IN
CARD (2)
CARD I/O
CARD I/O
Figure 10. ADG3243 in a Hot Plug Application
There are many systems, such as docking stations, PCI boards
for servers, and line cards for telecommunications switches, that
require the ability to handle hot swapping. If the bus can be
isolated prior to insertion or removal, there is more control over
the hot swap event. This isolation can be achieved using bus
ADG3243
switches. The bus switches are positioned on the hot swap card
between the connector and the devices. During hot swap, the
ground pin of the hot swap card must connect to the ground pin
of the backplane before any other signal or power pins.
Analog Switching
Bus switches can be used in many analog switching applications,
for example, video graphics. Bus switches can have lower on
resistance, smaller ON and OFF channel capacitance, and thus
improved frequency performance than their analog counterparts.
The bus switch channel itself, consisting solely of an NMOS
switch, limits the operating voltage (see TPC 1 for a typical
plot), but in many cases, this does not present an issue.
High Impedance during Power-Up/Power-Down
To ensure the high impedance state during power-up or powerdown, BEx should be tied to V
minimum value of the resistor is determined by the currentsinking capability of the driver.
through a pull-up resistor; the
CC
REV. 0
–9–
Page 10
ADG3243
OUTLINE DIMENSIONS
8-Lead Small Outline Transistor Package [SOT-23]
(RJ-8)
Dimensions shown in millimeters
2.90 BSC
1.60 BSC
PIN 1
1.30
1.15
0.90
0.15 MAX
7
2
1.95
BSC
5 6
4
2.80 BSC
0.65 BSC
1.45 MAX
SEATING
PLANE
0.22
0.08
8
1 3
0.38
0.22
COMPLIANT TO JEDEC STANDARDS MO-178BA
8ⴗ
4ⴗ
0ⴗ
0.60
0.45
0.30
REV. 0–10–
Page 11
–11–
Page 12
C04310–0–8/03(0)
–12–
Loading...
+ hidden pages
You need points to download manuals.
1 point = 1 manual.
You can buy points or you can get point for every manual you upload.