AN1672 Datasheet, PDF(6/10 Page) ON Semiconductor

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AN1672 Datasheet, PDF (6/10 Pages) ON Semiconductor – The ECL Translator Guide

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AN1672/D

From LVPECL to LVTTL/LVCMOS

Devices MC100EPT21, MC100EPT23, MC100LVELT23,

and MC100EPT26 translate LVPECL signals to

LVTTL/LVCMOS. Standard levels for the LVTTL and

LVCMOS are the same.

There are no âopen inputâ default circuits to force the

outputs to a determined state. Provisions should be taken to

prevent autoâoscillation. If the inputs are permitted to

converged on the same voltage (within the VIHCMR range),

or merely left floating, autoâoscillation will initiate.

There are no powerup sequence requirements or power

sequence restrictions. If either VCC or VEE supplies are not

present, such as during an open pin condition, the output

falls to near zero without harm or damage to the device.

Outputs of these devices typically display about 2X the

required data sheet drive. For example, at VOLmin the drive

is required to sink 24 mA and will typically sink >50 mA. At

VOH, the spec drive is â3.0 mA and will typically source

>8 mA.

Typical drive current strength of the TTL output is shown

in the following two tables, Table 7 and Table 8, and their

graphs, Figure 3 and Figure 4.

Typical EPT TTL series output impedance in the HIGH state is about 5 W. In the LOW state output impedance is about 15 W.AC

measurements are made to the 1.5 V point for the AC characteristics such as tpd and skew.

Table 7. EPT TTL Series Drive LOW Current (IOL) vs

0.20

Voltage (VOL) at 255C

Iout

Vout

0.16

0.004

0.020

0.022

0.104

0.12

0.039

0.058

0.200

0.08

0.295

0.082

0.118

0.415

0.04

0.596

25Â°C

0.158

0.1963

0.800

1.000

0.2

0.4

0.6

0.8

VOL (V)

Figure 3. EPT TTL Series Drive LOW Current (IOL)

versus Voltage (VOL) at 255C

Table 8. EPT Series TTL Drive HIGH Current (IOH) vs

Voltage (VOH) at 255C

Iout

â0.0146

Vout

2.32

â0.0112

2.36

â0.0081

2.40

â0.0052

2.44

â0.0028

2.48

â0.0011

2.52

â0.0003

2.56

â0.016

â0.012

â0.008

â0.004

2.3 2.32 2.36 2.4 2.44 2.48 2.52 2.56

VOH (V)

Figure 4. EPT Series TTL Drive HIGH Current (IOH)

versus Voltage (VOH)

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