580M-01ILFT Datasheet 580M-01ILFT, 580M-01ILF, 580M-01LF | P4-P6

ICS580-01

GLITCH-FREE CLOCK MULITPLEXER CLOCK MULTIPLEXER

IDT™ / ICS™

GLITCH-FREE CLOCK MULITPLEXER 4

ICS580-01 REV L 051310

Device Operation

The ICS580-01 consists of a glitch free mux between INA and INB controlled by SELB. The device is designed to

switch between two clocks, whether running or not. In the first example, clocks are running on both INA and INB.

When SELB changes, the output clock goes low after three cycles of the output clock (nominally). The output then

stays low for three cycles of the new input clock (nominally) and then starts with the new input clock. This is shown

in Figure 1.

In the second example, one of the inputs was selected and running but has since stopped (either high or low). This

is indicated by either NO_INA or NO_INB going high depending on whether INA or INB has stopped. These signals

go high following a selectable time-out period after the clock has stopped. The timeout period is determined by the

DIV input in. The SELB pin is now changed to select the new input clock which is running. The output clock

immediately goes low and stays low for three cycles of the new input clock and then starts with the new input clock.

Figure 2 shows an example of this

INA

INB

SELB

CLK1, 2

Figure 1

INA

INB

SELB

NO_INA

Figure 2

Timeout

CLK1, 2

ICS580-01

GLITCH-FREE CLOCK MULITPLEXER CLOCK MULTIPLEXER

IDT™ / ICS™

GLITCH-FREE CLOCK MULITPLEXER 5

ICS580-01 REV L 051310

Application Example

In the third example, the ICS580-01 is configured to automatically switch clocks when an input stops. The clock that

could stop is connected to INA while the backup clock (always running) is connected to INB. The output NO_INA is

connected to SELB. This means that when the clock on INA stops, NO_INA goes high selecting the clock on INB

which is muxed to the output after three cycles. When the clock on INA restarts, NO_INA immediately goes low,

selecting the clock on INA. The output then switches in the manner described in the first example.

The circuit diagram in Figure 3 shows a typical connection for this example. Note that CLK2 and NO_INB are

unused and are disabled by grounding OE2 and OE4. A 33Ω series termination resistor is used on the clock output

and two decoupling capacitors of 0.01µF are used. All other inputs are left floating and are therefore pulled high by

the on-chip pull-ups.

Output Enable

Each output has a dedicated output enable pin. If an output is unused, it should be tri-stated by tying the

appropriate output enable pin to ground.

External Components

The ICS580-01 requires two 0.01µF decoupling capacitors, one between VDDI and GND and one between VDDC

and GND. Series termination resistors of 33Ω can be used on CLK1 and CLK2.

NO_INA

SELB

NO_INB

DIV

GND

VDDI

OE2

INA

INB

GND

OE4

OE3

OE1

VDDC

CLK1

CLK2

VDD

0.01µF

33Ω

0.01µF

Normal Clock

Backup Clock

Output Clock

ICS580-01

GLITCH-FREE CLOCK MULITPLEXER CLOCK MULTIPLEXER

IDT™ / ICS™

GLITCH-FREE CLOCK MULITPLEXER 6

ICS580-01 REV L 051310

Split Power Supplies

The VDDI pin provides the power for the INA and INB input buffers only. All the other inputs and the rest of the chip

are connected to VDDC. This allows for supply voltage translation. For example, INA and INB could be 5V clocks

(VDDI = 5V) and the rest of the chip could use a 3.3V supply on VDDC giving 3.3V output clocks. For correct

operation VDDI must always be greater than or equal to VDDC.

Absolute Maximum Ratings

Stresses above the ratings listed below can cause permanent damage to the ICS580-01. These ratings, which are

standard values for IDT commercially rated parts, are stress ratings only. Functional operation of the device at these

or any other conditions above those indicated in the operational sections of the specifications is not implied.

Exposure to absolute maximum rating conditions for extended periods can affect product reliability. Electrical

parameters are guaranteed only over the recommended operating temperature range.

Recommended Operation Conditions

DC Electrical Characteristics

Unless stated otherwise, VDD = 3.3V ±5%, Ambient Temperature -40 to +85° C

Item Rating

Supply Voltage, VDD 7V

All Inputs and Outputs -0.5V to VDD+0.5V

Ambient Operating Temperature 0 to +70° C

Ambient Operating Temperature -40 to +85° C

Storage Temperature -65 to +150° C

Junction Temperature 125° C

Soldering Temperature 260° C

Parameter Min. Typ. Max. Units

Ambient Operating Temperature 0 +70 ° C

Ambient Operating Temperature -40 +85 ° C

Power Supply Voltage (measured in respect to GND) +2.5 +5.5 V

Parameter Symbol Conditions Min. Typ. Max. Units

Operating Voltage VDDC 2.5 5.5 V

VDDI VDDC 5.5 V

Supply Current IDD 50 MHz, no load 6 mA

Input High Voltage V

Non-clock inputs 2 VDDC V

Input Low Voltage V

Non-clock inputs 0.8 V

Input High Voltage V

INA and INB only

Note 3

(VDDC/2)+1 VDDI V

P1-P3 P4-P6 P7-P9 P10-P12 P13-P13

580M-01ILFT

Mfr. #:

Buy 580M-01ILFT

Manufacturer:

IDT

Description:

Clock Drivers & Distribution GLITCH-FREE CLOCK MULTIPLEXER

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580M-01ILFT

580M-01ILFT

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