TSZ121 datasheet(21/38 Pages) STMICROELECTRONICS

21 / 38 page

TSZ121, TSZ122, TSZ124

Application information

DocID023563 Rev 5

21/38

Figure 43: Stability criteria with a serial resistor at VDD

= 5 V

Figure 44: Stability criteria with a serial resistor at VDD

= 1.8 V

Figure 45: Test configuration for Riso

5.8

PCB layout recommendations

Particular attention must be paid to the layout of the PCB, tracks connected to the amplifier,

load, and power supply. The power and ground traces are critical as they must provide

adequate energy and grounding for all circuits. Good practice is to use short and wide PCB

traces to minimize voltage drops and parasitic inductance.

In addition, to minimize parasitic impedance over the entire surface, a multi-via technique

that connects the bottom and top layer ground planes together in many locations is often

used.

The copper traces that connect the output pins to the load and supply pins should be as

wide as possible to minimize trace resistance.

5.9

Optimized application recommendation

TSZ121, TSZ122, and TSZ124 devices are based on chopper architecture. As they are

switched devices, it is strongly recommended to place a 0.1 µF capacitor as close as

possible to the supply pins.

A good decoupling has several advantages for an application. First, it helps to reduce

electromagnetic interference. Due to the modulation of the chopper, the decoupling

capacitance also helps to reject the small ripple that may appear on the output.

TSZ121, TSZ122, and TSZ124 devices have been optimized for use with 10 kΩ in the

feedback loop. With this, or a higher value of resistance, these devices offer the best

performance.

TSZ121 Datasheet(PDF) 21 Page - STMicroelectronics