What types of voltage level translation ICs (level shifters) are available?

ICs that can convert the voltage level of logic signals include general-purpose logic ICs (with tolerant function and TTL input) and dual-power level shifter ICs (buffer type, bus switch type) dedicated to voltage level conversion. (table 1)

A brief description of each is given below.

  1. Level shifting using standard logic IC or a single-supply level shifter IC (Fig. 1)
    Standard logic ICs with a tolerant function allow down translation whereas those with a TTL input allow up translation. Single-supply level shifter ICs provide both a TTL input and a tolerant function and thus allow both up and down translation.
  2. Level shifting using a dual-supply level-shifting bus buffer IC (Fig. 2)
    Incorporating a buffer, a bus buffer IC provides a sufficient drive capability.
  3. Level shifting using a dual-supply level-shifting bus switch IC (Fig. 3)
    A bus switch IC uses pull-up resistors for level-shifting. Although the bus switch does not have a drive capability, it is fast because its input and output pins are short-circuited with low resistance when it is on.

Refer to the application note below for the selection of the level shifter.
→ Tips for Selecting Level Shifters(Voltage Translation ICs) (PDF:2.62MB)

Table-1 Voltage translation using general-purpose logic ICs
 

Supply Voltage

Circuit Type

Up
Translation

Down
Translation

Fig. 1

Single Supply

Buffer

✔

(TTL-Input : 3.3 V→5 V)

✔

(Tolerant : 5 V→3.3 V)

Fig. 2

Dual Supply

Buffer

✔

(VCCA → VCCB)

✔

(VCCB → VCCA)

Fig. 3

Dual Supply

SW

✔

(VCCA → VCCB)

✔

(VCCB → VCCA)
Fig. 1 General-purpose logic ICs (Input-tolerant function and a TTL input) and Level Shifter (Single Supply)
Fig. 1 General-purpose logic ICs (Input-tolerant function and a TTL input) and Level Shifter (Single Supply)

*1: The VCX series allows down translation from 3.3 V to 1.8 V since it is designed for low-voltage applications operating at 3.6 V or less.

Fig. 2 Dual supply Level shifters (Buffer type)
Fig. 2 Dual supply Level shifters (Buffer type)
Fig. 3 Dual supply Level shifters（Bus switch type）
Fig. 3 Dual supply Level shifters（Bus switch type）

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