Diodes Incorporated Shrinks Their Popular Dual- and Quad-channel Bus Switches

January 17, 2020 by Gary Elinoff

Available in ultra-thin QFN (UQFN) packages, the new devices measure at 3mm x 3mm x 0.65mm.

Diodes Incorporated has rolled out new dual- and quad-channel 4:1 and 2:1 bus switches, which join a well-established product line. 


UQFN packages_Feature

Diode Incorporated’s bus switches are now available in smaller UQFN packages. Image used courtesy of Diodes Incorporated


The devices' diminutive size means that they can occupy even less board space than their predecessors.


Family Heritage

The new devices are the dual 4:1 channel PI3B3253ZHD and the quad 2:1 channel PI3B3257ZHDPI3CH480ZHD, and PI5C3257ZHD. Older versions of the family are available in QSP and TSSOP packages. These earlier devices offer the advantages of pin-to-pin compatibility with industry-standard 74 series logic.

It is noteworthy that Diodes Incorporated supplies one datasheet for the QSP, TSSOP, and the new ZHD versions of each device. Aside from package size and pin configuration, the units are quite similar.


Critical Specifications

In addition to their small size, the UQFN packages for the new series feature a thermal pad to facilitate effective heat dissipation. All members also feature:

  • On resistance of 5Ω (typ)
  • Operate over a -40℃ to +85℃ temperature range
  • Draw 0.5W and supply 120mA signal output

Diodes incorporated also asserts that the new series offers low quiescent power and low propagation delay. The devices are also said to be encased in green, PB-free packaging.


Dual 4:1 Multiplexer

The PI3B3253

As a dual 4:1 multiplexer, the (PDF) PI3B3253 draws a typical quiescent current of 0.2 µA and features a maximum switching speed of 5.2ns. The supply voltage is 3.3V.


Block diagram of PI3B3253

Block diagram of PI3B3253. Image used courtesy of (PDF) Diodes Incorporated


YA and YB can be switched to IA0 and IBO; IA1 and IB1; IA2 and IB2; or IA3 or IB3. This switch can occur by changing the appropriate inputs to EA, EB, S0, and SI, as defined by a documented truth table. YA and YB can also be disabled.


Quad 2:1 Multiplexer

The PI3B3257

This quad 2:1 multiplexer draws a typical quiescent current of 0.1 µA and features a maximum switching speed of 4.8ns. Like the PI3B3253, the (PDF) PI3B3257 supply voltage is also 3.3V.


Block diagram of the PI3B3257

Block diagram of the PI3B3257. Image used courtesy of (PDF) Diodes Incorporated


YA, YB, YC, and YD are connected to IA0, IB0; IC0 and ID0; or to IA1, IB1, IC1 and ID1 by appropriate input to E and S. The outputs can be disabled here as well.



This (PDF) unit can work with both 2.5V and 3.3V power supplies. The PI3CH480 can switch signals with bandwidths up to 500MHz. The typical quiescent current is 0.25mA.


Truth table for PI3CH480

Truth table for PI3CH480. Image used courtesy of (PDF) Diodes Incorporated

Connecting outputs to inputs are similar to the PI3B3257.



The (PDF) PI5C3257 also features a typical quiescent current of 0.2 µA. Matching outputs to inputs is similar to PI3B3257.



These devices will find use in virtually all types of electronic equipment where saving board space is a critical design criterion. Examples include an IP phone, IoT, tablets, and notebooks. It might also be useful in 4-bit bus multiplexing and demultiplexing, optical networking, telecommunications, networking equipment, and PBX.


Around the Industry

There are several other multiplexer/demultiplexer bus switches around the industry that are worth considering.

One of these includes the 74FST3257 from ON Semiconductor is a quad 2:1 multiplexer/demultiplexer bus switch with a typical on-resistance of 4Ω. There is less than 0.25ns signal delay through the device.

Another is Nexperia’s CBT3257A, a family of quad multiplexer/demultiplexer bus switches. On-resistance for these devices are specified at 5Ω. The delay is 0.25ns.



Manufacturers continually try to optimize existing components—for instance, by decreasing size. Do you keep an eye on your favorite components for specification changes? What changes are you most eager to see? Share your thoughts in the comments below.