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ISL59420
Data Sheet September 22, 2005 FN7459.1
400MHz Multiplexing Amplifier
The ISL59420 is a 420MHz bandwidth 2:1 multiplexing amplifier designed primarily for video switching. This Mux-amp has user-settable gain and also feature a high speed three-state function to enable the output of multiple devices to be wired together. All logic inputs have pull-downs to ground and may be left floating. The ENABLE pin, when pulled high, sets the ISL59420 to the low current power-down mode for power sensitive applications - consuming just 5mW.
TABLE 1. CHANNEL SELECT LOGIC TABLE S0 0 1 X X ENABLE 0 0 1 0 HIZ 0 0 X 1 OUTPUT IN0 IN1 Power Down High Z
Features
* 420MHz (-3dB) Bandwidth (AV = 1, VOUT = 400mVP-P) * 165MHz (-3dB) Bandwidth (AV = 2, VOUT = 2VP-P) * Slew Rate (AV = 1, RL = 500, VOUT = 4V) . . . . . .966V/s * Slew Rate (AV = 2, RL = 500, VOUT = 5V) . . . . .1462V/s * Selectable Gain * High Speed Three-State Output (HIZ) * Low Current Power-Down . . . . . . . . . . . . . . . . . . . . .5mW * Pb-Free Plus Anneal Available (RoHS Compliant)
Applications
* HDTV/DTV Analog Inputs * Video Projectors * Computer Monitors
Pinout
ISL59420 (10 LD MSOP) TOP VIEW
S0 GND IN0 ENABLE IN1 1 2 3 4 5 + 10 9 8 7 6 INOUT V+ VHIZ
* Set-Top Boxes * Security Video * Broadcast Video Equipment
Ordering Information
PART NUMBER ISL59420IU ISL59420IU-T7 ISL59420IU-T13 ISL59420IUZ (Note) ISL59420IUZ-T7 (Note) ISL59420IUZ-T13 (Note) PART MARKING BBNAA BBNAA BBNAA BBPAA BBPAA BBPAA PACKAGE 10 Ld MSOP 10 Ld MSOP 10 Ld MSOP 10 Ld MSOP (Pb-free) 10 Ld MSOP (Pb-free) 10 Ld MSOP (Pb-free) TAPE & REEL 7" 13" 7" 13" PKG. DWG. # MDP0043 MDP0043 MDP0043 MDP0043 MDP0043 MDP0043
Functional Diagram
S0 EN0 DECODE IN0 EN1 IN1 + OUT IN-
AMPLIFIER BIAS HIZ
NOTE: Intersil Pb-free plus anneal products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate termination finish, which are RoHS compliant and compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.
ENABLE
ENABLE pin must be low in order to activate the HIZ state
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright (c) Intersil Americas Inc. 2005. All Rights Reserved. All other trademarks mentioned are the property of their respective owners.
ISL59420
Absolute Maximum Ratings (TA = 25C)
Supply Voltage (V+ to V-). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11V Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . V- -0.5V, V+ +0.5V Supply Turn-on Slew Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . 1V/s IN- Input Current (Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5mA Digital & Analog Input Current (Note 1) . . . . . . . . . . . . . . . . . . 50mA Output Current (Continuous) . . . . . . . . . . . . . . . . . . . . . . . . . . 50mA ESD Rating Human Body Model (Per MIL-STD-883 Method 3015.7). . . . 2.5kV Machine Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300V Storage Temperature Range . . . . . . . . . . . . . . . . . .-65C to +150C Ambient Operating Temperature . . . . . . . . . . . . . . . .-40C to +85C Operating Junction Temperature . . . . . . . . . . . . . . .-40C to +125C Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Curves JA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Curves
CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
NOTE: 1. If an input signal is applied before the supplies are powered up, the input current must be limited to these maximum values.
IMPORTANT NOTE: All parameters having Min/Max specifications are guaranteed. Typical values are for information purposes only. Unless otherwise noted, all tests are at the specified temperature and are pulsed tests, therefore: TJ = TC = TA
Electrical Specifications
PARAMETER GENERAL
V+ = +5V, V- = -5V, GND = 0V, TA = 25C, RL = 500 to GND unless otherwise specified. CONDITIONS MIN TYP MAX UNIT
DESCRIPTION
IS Enabled
IS Disabled
Supply Current Disabled Supply Current I+ Disabled Supply Current I-
No load, VIN = 0V, ENABLE Low No load, VIN = 0V, ENABLE High No load, VIN = 0V, ENABLE High VIN = 2V, RL = 500, AV = 2 VIN = -2V, RL = 500, AV = 2 RL = 10 to GND
9.5 0.5
11 1 3
13 1.5 10
mA mA A V
VOUT
Positive Output Swing Negative Output Swing
3.5
3.9 -3 -2.8
V mA
IOUT VOS Ib+ IbRout
Output Current Output Offset Voltage Input Bias Current Feedback Bias Current Output Resistance
80 -12
130 4 -2.5 7 1.4 0.2 10 +12 -1.5 15
mV A A M M
VIN = 0V
-4 -15
HIZ = logic high, (DC), AV = 1 HIZ = logic low, (DC), AV = 1
RIN ACL or AV ITRI LOGIC VH VL IIH IIL AC GENERAL - 3dB BW
Input Resistance Voltage Gain Output Current in Three-state
VIN = 3.5V RF = RG = 600, VOUT = 3V VOUT = 0V 1.990 -20
2.005 6
2.020 20
V/V A
Input High Voltage (Logic Inputs) Input Low Voltage (Logic Inputs) Input High Current (Logic Inputs) Input Low Current (Logic Inputs)
2 0.8 55 -10 90 0 135 10
V V A A
-3dB Bandwidth
AV = 1, RF = 200, VOUT = 400MVP-P, CL = 5.5pF, CG = 0.6pF AV = 2, RF = RG = 453, VOUT = 2VP-P, CL = 5.5pF, CG = 0.6pF
420 165
MHz MHz
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FN7459.1 September 22, 2005
ISL59420
Electrical Specifications
PARAMETER 0.1dB BW V+ = +5V, V- = -5V, GND = 0V, TA = 25C, RL = 500 to GND unless otherwise specified. (Continued) CONDITIONS AV = 1, RF = 200, VOUT = 100mVP-P, CL = 5.5pF, CG = 0.6pF AV = 2, RF = RG = 453, VOUT = 2VP-P, CL = 5.5pF, CG = 0.6pF dG Differential Gain Error NTC-7, RL = 150, CL = 5.5pF, AV = 1 NTC-7, RL = 150, CL = 5.5pF, AV = 2 dP Differential Phase Error NTC-7, RL = 150, CL = 5.5pF, AV = 1 NTC-7, RL = 150, CL = 5.5pF, AV = 2 +SR Slew Rate 25% to 75%, AV = 1, VOUT = 4V, RL = 500, CL = 5.5pF 25% to 75%, AV = 2, VOUT = 5V, RL = 500, CL = 5.5pF -SR Slew Rate 25% to 75%, AV = 1, VOUT = 4V, RL = 500, CL = 5.5pF 25% to 75%, AV = 2, VOUT = 5V, RL = 500, CL = 5.5pF PSRR ISO Power Supply Rejection Ratio Channel Isolation DC, PSRR V+ and V- combined f = 10MHz, Ch-Ch X-Talk and Off Isolation, CL = 5.5pF -60 MIN TYP 25 60 0.01 0.05 0.02 0.02 966 1462 788 1171 -68 75 MAX UNIT MHz MHz % % V/s V/s V/s V/s dB dB
DESCRIPTION 0.1dB Bandwidth
SWITCHING CHARACTERISTICS VGLITCH Channel-to-Channel Switching Glitch ENABLE Switching Glitch HIZ Switching Glitch tSW-L-H tSW-H-L Channel Switching Time Low to High Channel Switching Time High to Low VIN = 0V, CL = 5.5pF, AV = 2 VIN = 0V, CL = 5.5pF, AV = 2 VIN = 0V, CL = 5.5pF, AV = 2 1.2V logic threshold to 10% movement of analog output 1.2V logic threshold to 10% movement of analog output 36 475 360 24 19 mVP-P mVP-P mVP-P ns ns
TRANSIENT RESPONSE tR, tF Rise & Fall Time, 10% to 90% AV = 1, RF = 200, VOUT = 100mVP-P, CL = 5.5pF, CG = 0.6pF AV = 2, RF = RG = 453, VOUT = 2VP-P, CL = 5.5pF, CG = 0.6pF tS OS 0.1% Settling Time Overshoot AV = 2, RF = RG = 453, VOUT = 2VP-P, CL = 5.5pF, CG = 0.6pF AV = 1, RF = 200, VOUT = 100mVP-P, CL = 5.5pF, CG = 0.6pF AV = 2, RF = RG = 453, VOUT = 2VP-P, CL = 5.5pF, CG = 0.6pF tPLH Propagation Delay - Low to High, 10% to 10% AV = 1, RF = 200, VOUT = 100mVP-P, CL = 5.5pF, CG = 0.6pF AV = 2, RF = RG = 453, VOUT = 2VP-P, CL = 5.5pF, CG = 0.6pF tPHL Propagation Delay- High to Low, 10% to 10% AV = 1, RF = 200, VOUT = 100mVP-P, CL = 5.5pF, CG = 0.6pF AV = 2, RF = RG = 453, VOUT = 2VP-P, CL = 5.5pF, CG = 0.6pF 0.83 1.64 8.8 24 10 0.5 1.01 0.65 1.08 ns ns ns % % ns ns ns ns
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FN7459.1 September 22, 2005
ISL59420 Typical Performance Curves VS = 5V, RL = 500 to GND, TA = 25C, unless otherwise specified.
5 4 3 NORMALIZED GAIN (dB) 2 1 0 -1 -2 -3 -4 -5 1 10 FREQUENCY (MHz) 100 1000 CL INCLUDES 1.6pF BOARD CAPACITANCE CL = 1.6pF AV = 1 VOUT = 100mVP-P RF = 200 CL = 9.7pF CL = 7.2pF CL = 5.5pF NORMALIZED GAIN (dB) 5 AV = 1 VOUT = 100mVP-P 3 CL = 5.5pF RF = 200 2 4 1 0 RL = 150 -1 -2 -3 -4 -5 1 10 100 1000 FREQUENCY (MHz) RL = 75 RL = 500 RL = 1k
FIGURE 1. SMALL SIGNAL GAIN vs FREQUENCY vs CL
FIGURE 2. SMALL SIGNAL GAIN vs FREQUENCY vs RL
5 4 3 NORMALIZED GAIN (dB) 2 1 0 CL = 9.7pF -1 -2 -3 -4 -5 1 10 FREQUENCY (MHz) 100 1000 CL INCLUDES 1.6pF BOARD CAPACITANCE CL = 1.6pF CL = 7.2pF CL = 5.5pF AV = 2 VOUT = 2VP-P RG = RF = 453 NORMALIZED GAIN (dB)
5 4 3 2 1 0 -1 -2 RL = 150 -3 -4 -5 1 10 100 1000 FREQUENCY (MHz) RL = 75 RL = 500 RL = 1k AV = 2 VOUT = 2VP-P CL = 5.5pF RG = RF = 453 RL = 75
FIGURE 3. LARGE SIGNAL GAIN vs FREQUENCY vs CL
FIGURE 4. LARGE SIGNAL GAIN vs FREQUENCY vs RL
0.8 A =1 0.7 VV OUT = 100mVP-P RF = 200 0.6 0.5 0.4 0.3 0.2 0.1 0 -0.1 -0.2 1 10 FREQUENCY (MHz) 100 1000 CL INCLUDES 1.6pF BOARD CAPACITANCE CL = 9.7pF CL = 7.2pF CL = 5.5pF NORMALIZED GAIN (dB) CL = 1.6pF
0.8 RL = 75 AV = 1 VOUT = 100mVP-P 0.6 CL = 5.5pF RL = 150 0.5 RF = 200 0.7 0.4 0.3 0.2 0.1 0 -0.1 -0.2 1 10 100 1000 FREQUENCY (MHz) RL = 1k RL = 500
FIGURE 5. SMALL SIGNAL 0.1dB GAIN vs FREQUENCY vs CL
NORMALIZED GAIN (dB)
FIGURE 6. SMALL SIGNAL 0.1dB GAIN vs FREQUENCY vs RL
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FN7459.1 September 22, 2005
ISL59420 Typical Performance Curves VS = 5V, RL = 500 to GND, TA = 25C, unless otherwise specified. (Continued)
0.2 0.1 NORMALIZED GAIN (dB) 0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 -0.7 -0.8 1 10 FREQUENCY (MHz) 100 1000 CL INCLUDES 1.6pF BOARD CAPACITANCE AV = 2 VOUT = 2VP-P RG = RF = 453 CL = 5.5pF CL = 1.6pF CL = 9.7pF CL = 7.2pF NORMALIZED GAIN (dB) 0.5 0.4 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 1 10 100 1000 FREQUENCY (MHz) RL = 1k RL = 500 AV = 2 VOUT = 2VP-P CL = 5.5pF RG = RF = 453 RL = 75
RL = 150
FIGURE 7. LARGE SIGNAL 0.1dB GAIN vs FREQUENCY vs CL
FIGURE 8. LARGE SIGNAL 0.1dB GAIN vs FREQUENCY vs RL
-10 20 10 0 -10 PSRR (dB) -20 -30 -40 -50 -60 -70 -80 0.3 1 10 FREQUENCY (MHz) PSRR (V-) 100 1000 PSRR (V+) AV = 2 VIN = 200mVP-P CL = 5.5pF RG = RF = 453 -20 -30 -40 -50 (dB) -60 -70 -80 -90 -100
AV = 2 VIN = 1VP-P CL = 5.5pF RG = RF = 453
CROSSTALK
OFF ISOLATION
-110 0.001
0.01
0.1
1
3
6 10
100
500
FREQUENCY (MHz)
FIGURE 9. PSRR CHANNELS
FIGURE 10. CROSSTALK AND OFF ISOLATION
24 -IIN CURRENT NOISE (pA/Hz)
AV = 1, RF = 500 INPUT VOLTAGE NOISE (nV/Hz)
60
AV = 1, RF = 500
20
50
16
40
12
30
8
20
4 0 0.1
10 0 0.1
1
10
100
1
10
100
FREQUENCY (kHz)
FREQUENCY (kHz)
FIGURE 11. INPUT NOISE vs FREQUENCY
FIGURE 12. INPUT NOISE vs FREQUENCY
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FN7459.1 September 22, 2005
ISL59420 Typical Performance Curves VS = 5V, RL = 500 to GND, TA = 25C, unless otherwise specified. (Continued)
S0 1V/DIV 1V/DIV
S0
0 20mV/DIV 1V/DIV
0 VOUT 0
0 VOUT
20ns/DIV
20ns/DIV
FIGURE 13. CHANNEL TO CHANNEL SWITCHING GLITCH VIN = 0V, AV = 2
FIGURE 14. CHANNEL TO CHANNEL TRANSIENT RESPONSE VIN = 1V, AV = 2
ENABLE 1V/DIV 1V/DIV
ENABLE
0 200mV/DIV VOUT 0 1V/DIV
0
VOUT 0
20ns/DIV
20ns/DIV
FIGURE 15. ENABLE SWITCHING GLITCH VIN = 0V, AV = 2
FIGURE 16. ENABLE TRANSIENT RESPONSE VIN = 1V, AV = 2
HIZ 1V/DIV 1V/DIV
HIZ
0 100mV/DIV
0
0 VOUT
1V/DIV
0
VOUT
20ns/DIV
20ns/DIV
FIGURE 17. HIZ SWITCHING GLITCH VIN = 0V, AV = 2
FIGURE 18. HIZ TRANSIENT RESPONSE VIN = 1V, AV = 2
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FN7459.1 September 22, 2005
ISL59420 Typical Performance Curves VS = 5V, RL = 500 to GND, TA = 25C, unless otherwise specified. (Continued)
160 120 OUTPUT VOLTAGE (mV) 80 40 0 -40 -80 -120 -160 TIME (4ns/DIV) AV = 1 CL = 5.5pF RF = 200 RL = 500 2.4 2 OUTPUT VOLTAGE (V) 1.6 1.2 0.8 0.4 0 -0.4 -0.8 AV = 2 CL = 5.5pF RG = RF = 453 RL = 500 TIME (4ns/DIV)
FIGURE 19. SMALL SIGNAL TRANSIENT RESPONSE
FIGURE 20. LARGE SIGNAL TRANSIENT RESPONSE
JEDEC JESD51-7 HIGH EFFECTIVE THERMAL CONDUCTIVITY TEST BOARD 1 0.9 POWER DISSIPATION (W) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 25 50 75 85 100 125 AMBIENT TEMPERATURE (C) POWER DISSIPATION (W) 870mW
M
JA
JEDEC JESD51-3 LOW EFFECTIVE THERMAL CONDUCTIVITY TEST BOARD 0.6 0.5 486mW 0.4 0.3 0.2 0.1 0 0 25 50 75 85 100 125 AMBIENT TEMPERATURE (C)
JA
=1 10 15 C /W
SO
P
M SO P =2 10 06 C /W
FIGURE 21. PACKAGE POWER DISSIPATION vs AMBIENT TEMPERATURE
FIGURE 22. PACKAGE POWER DISSIPATION vs AMBIENT TEMPERATURE
100 AV = 1, VOUT = 100mVP-P AV = 2, VOUT = 2VP-P OUTPUT RESISTANCE ()
10
AV = 2 1
AV = 1
0.1 0.1
1
10 FREQUENCY (MHz)
100
1000
FIGURE 23. ROUT vs FREQUENCY
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FN7459.1 September 22, 2005
ISL59420 Pin Descriptions
PIN NUMBER 1 2 3 4 5 6 7 8 9 10 PIN NAME S0 GND IN0 ENABLE IN1 HIZ VV+ OUT INEquivalent Circuit Circuit 2 Circuit 4 Circuit 1 Circuit 2 Circuit 1 Circuit 2 Circuit 4 Circuit 4 Circuit 3 Circuit 1 DESCRIPTION Channel selection pin LSB (binary logic code) Ground pin Input for channel 0 Device enable (active low); there are internal pull-down resistors, so the device will be active with no connection; "HI" puts device into power-down mode. Input for channel 1 Output disable (active high); there are internal pull-down resistors, so the device will be active with no connection; "HI" puts the output in high impedance state. Negative power supply Positive power supply Output Inverting input of output amplifier
V+ IN VCIRCUIT 1. LOGIC PIN 21k 33k + 1.2V V+ GND. VCIRCUIT 2.
V+ OUT VCIRCUIT 3.
V+ GND VCIRCUIT 4.
CAPACITIVELY COUPLED ESD CLAMP
AC Test Circuits
ISL59420 RG RF Av = 1, 2 VIN 50 or 75 CL RS 475 or 462.5 50 or 75 TEST EQUIPMENT 50 or 75 RG ISL59420 RF Av = 1, 2 RS CL 50 or 75 TEST EQUIPMENT 50 or 75
VIN 50 or 75
FIGURE 24A. TEST CIRCUIT FOR MEASURING WITH A 50 OR 75 INPUT TERMINATED EQUIPMENT
FIGURE 24B. BACKLOADED TEST CIRCUIT FOR VIDEO CABLE APPLICATION. BANDWIDTH AND LINEARITY FOR RL LESS THAN 500 WILL BE DEGRADED.
NOTE: Figure 24A illustrates the optimum output load when connecting to input terminated equipment. Figure 24B illustrates backloaded test circuit for video cable applications.
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FN7459.1 September 22, 2005
ISL59420 Application Circuits
200 *CL = CT + COUT VIN 50 0.6pF + CG CT 1.6pF COUT 3.9pF VOUT RL = 500
PC BOARD CAPACITANCE
0.4pF < CG < 0.7pF
*CL: TOTAL LOAD CAPACITANCE CT: TRACE CAPACITANCE COUT: OUTPUT CAPACITANCE
FIGURE 25A. GAIN OF 1 APPLICATION CIRCUIT
453 453 VIN 50 0.6pF + CG CT 1.6pF COUT 3.9pF *CL = CT + COUT VOUT RL = 500
PC BOARD CAPACITANCE
0.4pF < CG < 0.7pF
FIGURE 25B. GAIN OF 2 APPLICATION CIRCUIT
Application Information
General
The ISL59420 is a 2:1 mux that is ideal as a matrix element in high performance switchers and routers. The ISL59420 is optimized to drive 5pF in parallel with a 500 load. The capacitance can be split between the PCB capacitance and an external load capacitance. Its low input capacitance and high input resistance provide excellent 50 or 75 terminations.
traces should not run parallel to each other. Small size surface mount resistors (604 or smaller) are recommended.
Capacitance at the Output
The output amplifier is optimized for capacitance to ground (CL) directly on the output pin. Increased capacitance causes higher peaking with an increase in bandwidth. The optimum range for most applications is ~1.0pF to ~6pF. The optimum value can be achieved through a combination of PC board trace capacitance (CT) and an external capacitor (COUT). A good method to maintain control over the output pin capacitance is to minimize the trace length (CT) to the next component, and include a discrete surface mount capacitor (COUT) directly at the output pin.
Parasitic Effects on Frequency Performance Capacitance at the Inverting Input
The AC performance of current-feedback amplifiers in the non-inverting gain configuration is strongly affected by stray capacitance at the inverting input. Stray capacitance from the inverting input pin to the output (CF), and to ground (CG), increase gain peaking and bandwidth. Large values of either capacitance can cause oscillation. The ISL59420 has been optimized for a 0.4pF to 0.7pF capacitance (CG). Capacitance (CF) to the output should be minimized. To achieve optimum performance the feedback network resistor(s) must be placed as close to the device as possible. Trace lengths greater than 1/4 inch combined with resistor pad capacitance can result in inverting input to ground capacitance approaching 1pF. Inverting input and output
Feedback Resistor Values
The AC performance of the output amplifier is optimized with the feedback resistor network (RF, RG) values recommended in the application circuits. The amplifier bandwidth and gain peaking are directly affected by the value(s) of the feedback resistor(s) in unity gain and gain >1 configurations. Transient response performance can be tailored simply by changing these resistor values. Generally, lower values of RF and RG increase bandwidth and gain peaking. This has the effect of decreasing rise/fall times and increasing overshoot.
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FN7459.1 September 22, 2005
ISL59420
Ground Connections
For the best isolation and crosstalk rejection, the GND pin and NIC pins must connect to the GND plane. connected to V+, can result in damaging currents through the ESD diodes and other active circuits within the device. Therefore, adequate current limiting on the digital and analog inputs is needed to prevent damage during the time the voltages on these inputs are more positive than V+.
Control Signals
S0, ENABLE, HIZ - These pins are TTL/CMOS compatible control inputs. The S0 pin selects which one of the inputs connect to the output. The ENABLE, HIZ pins are used to disable the part to save power and three-state the output amplifiers, respectively. For control signal rise and fall times less than 10ns the use of termination resistors close to the part will minimize transients coupled to the output.
HIZ State
An internal pull-down resistor connected to the HIZ pin ensures the device will be active with no connection to the HIZ pin. The HIZ state is established within approximately 25ns (Figure 18) by placing a logic high (>2V) on the HIZ pin. If the HIZ state is selected, the output is a high impedance 1.4M. Use this state to control the logic when more than one mux shares a common output. In the HIZ state the output is three-stated, and maintains its high Z even in the presence of high slew rates. The supply current during this state is basically the same as the active state.
Power-Up Considerations
The ESD protection circuits use internal diodes from all pins the V+ and V- supplies. In addition, a dV/dT- triggered clamp is connected between the V+ and V- pins, as shown in the Equivalent Circuits 1 through 4 section of the Pin Description table. The dV/dT triggered clamp imposes a maximum supply turn-on slew rate of 1V/s. Damaging currents can flow for power supply rates-of-rise in excess of 1V/s, such as during hot plugging. Under these conditions, additional methods should be employed to ensure the rate of rise is not exceeded. Consideration must be given to the order in which power is applied to the V+ and V- pins, as well as analog and logic input pins. Schottky diodes (Motorola MBR0550T or equivalent) connected from V+ to ground and V- to ground (Figure 23) will shunt damaging currents away from the internal V+ and V- ESD diodes in the event that the V+ supply is applied to the device before the V- supply. If positive voltages are applied to the logic or analog video input pins before V+ is applied, current will flow through the internal ESD diodes to the V+ pin. The presence of large decoupling capacitors and the loading effect of other circuits
ENABLE & Power Down States
The enable pin is active low. An internal pull-down resistor ensures the device will be active with no connection to the ENABLE pin. The Power Down state is established when a logic high (>2V) is placed on the ENABLE pin. In the Power Down state, the output has no leakage but has a large capacitance (on the order of 15pF), and is capable of being back-driven. Under this condition, large incoming slew rates can cause fault currents of tens of mA. Do not use this state as a high Z state for applications driving more than one mux on a common output.
Limiting the Output Current
No output short circuit current limit exists on this part. All applications need to limit the output current to less than 50mA. Adequate thermal heat sinking of the parts is also required.
V+ SUPPLY LOGIC POWER GND SIGNAL DE-COUPLING CAPS V- SUPPLY
SCHOTTKY PROTECTION S0 GND IN0 IN1
V+
V+ LOGIC CONTROL
EXTERNAL CIRCUITS
VV+
V+ V+ OUT VV-
V-
V-
FIGURE 26. SCHOTTKY PROTECTION CIRCUIT
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FN7459.1 September 22, 2005
ISL59420 PC Board Layout
The frequency response of this circuit depends greatly on the care taken in designing the PC board. The following are recommendations to achieve optimum high frequency performance from your PC board. * The use of low inductance components such as chip resistors and chip capacitors is strongly recommended. * Minimize signal trace lengths. Trace inductance and capacitance can easily limit circuit performance. Avoid sharp corners, use rounded corners when possible. Vias in the signal lines add inductance at high frequency and should be avoided. PCB traces greater than 1" begin to exhibit transmission line characteristics with signal rise/fall times of 1ns or less. High frequency performance may be degraded for traces greater than one inch, unless strip lines are used. * Match channel-channel analog I/O trace lengths and layout symmetry. This will minimize propagation delay mismatches. * Maximize use of AC de-coupled PCB layers. All signal I/O lines should be routed over continuous ground planes (i.e. no split planes or PCB gaps under these lines). Avoid vias in the signal I/O lines. * Use proper value and location of termination resistors. Termination resistors should be as close to the device as possible. * When testing use good quality connectors and cables, matching cable types and keeping cable lengths to a minimum. * Minimum of 2 power supply de-coupling capacitors are recommended (1000pF, 0.01F) as close to the device as possible. Avoid vias between the cap and the device because vias add unwanted inductance. Larger caps can be farther away. When vias are required in a layout, they should be routed as far away from the device as possible.
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FN7459.1 September 22, 2005
ISL59420 10 Ld MSOP Package Drawing
NOTE: The package drawing shown here may not be the latest version. To check the latest revision, please refer to the Intersil website at http://www.intersil.com/design/packages/index.asp
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems. Intersil Corporation's quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. 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 data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com 12
FN7459.1 September 22, 2005

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