MCU

VCC > 1.65V for Operation

VCC > 1.50V for Data Retention

GPIO

CLK

Q

D

2

1

3

4

5

CLK

SN74LVC1G79

GND

VCC

Copyright © 2017, Texas Instruments Incorporated

13

SN74LVC1G79

www.ti.com

SCES220U – APRIL 1999 – REVISED APRIL 2017

Product Folder Links: SN74LVC1G79

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Copyright © 1999–2017, Texas Instruments Incorporated

9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

9.1 Application Information

A useful application for the SN74LVC1G79 is using it as a data latch with low-voltage data retention. This

application implements the use of a microcontroller GPIO pin to act as a clock to set the output state and a

second GPIO to provide the input data. If the SN74LVC1G79 is being powered from 1.8 V and there is concern

that a power glitch could exist as low as 1.5 V, the device will retain the state of the Q output. An example of this

data retention is shown in Figure 8 where the VCC drops to 1.5 V and the Q output maintains the HIGH output

state when VCC returns to 1.8 V. If the VCC voltage drops below 1.5 V, data retention is not guaranteed.

9.2 Typical Application

Figure 7. Low Voltage Data Retention With SN74LVC1G79

9.2.1 Design Requirements

The SN74LVC1G79 device uses CMOS technology and has balanced output drive. Take care to avoid bus

contention because it can drive currents that would exceed maximum limits.

9.2.2 Detailed Design Procedure

1. Recommended input conditions:

–

For rise time and fall time specifications, see Δt/Δv in Recommended Operating Conditions.

–

For specified high and low levels, see VIH and VIL in Recommended Operating Conditions.

–

Input voltages are recommended to not go below 0 V and not exceed 5.5 V for any VCC. See

Recommended Operating Conditions.

2. Recommended output conditions:

–

Load currents should not exceed ±50 mA. See Absolute Maximum Ratings.

–

Output voltages are recommended to not go below 0 V and not exceed the VCC voltage. See

Recommended Operating Conditions.