• • • TEST & MEASUREMENT • • •


complete power supply design tool programme that can significantly ease the tasks of power supply design with many power products. The LTM8049 and ADP5070/ADP5071 allow us to


take a single positive input, boost it to the required positive supply, and invert it to generate the negative supply rail. The LTM8049 is a µModule solution that greatly simplifies the number of components needed to do this, we just need to add the input and output capacitors. As well as simplifying the design challenge in


terms of selecting components and board layout for switching regulators, the LTM8049 also minimises the PCB footprint and bill of materials needed for generating bipolar supplies. Where efficiency at lighter loads (<~100mA) is required, the ADP5070/ADP5071 is a better choice. Although the ADP5070 solution requires more external components, like inductors and diodes, it allows for more customisation of the power solution.


“


As well as simplifying the design challenge in terms of selecting components and board layout for switching regulators, the LTM8049 also minimises the PCB footprint and bill of materials needed for generating bipolar supplies.


Both the ADP5070 and LTM8049 have sync pins


that can be used to synchronise the switching frequency with the clock of an ADC to avoid switching the internal FETs during sensitive time periods for an ADC. The high efficiency of these regulators at a load current of a few 100mA makes them ideal for precision instrument supplies. The LT3032 incorporates both a positive and


efficient manner. Let’s consider a system that requires bipolar supply generation from a single positive input supply. Figure 1 shows power solutions that generate ±15V and ±5V and use positive and negative LDO regulators to filter/reduce the switching ripple as well as


generate additional rails like 5V, 3.3V, or 1.8V for powering signal conditioning circuitry or ADCs and DACs. The power rail solutions shown here were


designed using the system designer found in LTpowerCAD. The LTpowerCAD design tool is a


negative low noise LDO regulator in a single package with a wide operating range. The LT3023 incorporates two low noise, positive LDO regulators with a wide operating range. Both LDO regulators are configured to operate with minimal headroom (~0.5V) to maximise efficiency while also delivering good ripple rejection from the switching regulator stage. Both LDO regulators are available in small


LFCSP packages that reduce the PCB footprint and simplify the bill of materials. If much higher levels of PSRR are required from the LDO regulator to further reduce the switching ripple in the MHz range, then LDO regulators like the LT3094/LT3045 should be considered. The choice of how much PSRR is required in the LDO stage will depend on the PSRR of the components, like ADCs, DACs and amplifiers that are powered from the supply rails. Generally, higher PSRR LDO regulators are less efficient due to higher quiescent current. CN-0345 and CN-0385 are two examples of


Figure 1. Power solution for a non-isolated bipolar supply system (±15V and ±5V) with low supply ripple. electricalengineeringmagazine.co.uk


reference designs that implement this solution by using the ADP5070. These designs are for


ELECTRICAL ENGINEERING • JUNE 2026 17


“


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44