Supplement: Power Operating Condition Parameters 12VIN /5VOUT


Max IOUT Effi ciency at IMAX Thermal at IMAX


36VIN /12VOUT Effi ciency at IMAX


Max IOUT Effi ciency at IMAX Thermal at IMAX


LTM4712 12A


94.7% 58o


C 12A 96.2% C


96.2% 80o


Table 1. Buck mode thermal performance comparison, TA = 25°C, no forced cooling


Figure 4. ADI 40V boost regulator family.


LTM4613 8A


93% 70o


6A 93%


93% 101o


Figure 6. Boost mode effi ciency and current capability comparison: (a) 24VOUT effi ciency and (b) 36VOUT ef- fi ciency.


C


C


Figure 5.


Utilising as a boost regulator with inherent output short protection.


Figure 7. Confi gure as an inverting buck-boost regulator.


Operating Condition Parameters Continues from page 33


always starts in buck mode when VOUT is low, its input inrush current is tightly controlled and limited by the soft start of the inductor current. In summary, the four- switch buck-boost offers a more reliable step-up converter than a conventional boost regulator.


Figure 6 and Table 2 compare the efficiency, power capability, and thermal performance between the four-switch buck-boost µModule regulator and the buck µModule regulator. The first device demonstrates superior efficiency, extended current handling, and significantly better thermal performance. Both regulators share the same 16mm × 16mm footprint.


34 May 2025


Utilise four-switch buck-boost as an inverting buck-boost regulator for negative output voltage


Similar to standard buck converters, the four- switch buck-boost can also be confi gured in an inverting buck-boost topology for negative output applications. As shown in Figure 7, M1 and M2 switch complementary, with M3 off and M4 on during this operation. Note that the maximum voltage, VMAX = |VIN|+|VOUT|, must be less than 40V, which is the maximum voltage rating for the device. The magnitude of the DC through the inductor, IL, is given by IL= IOUT/(1-D), where D is the duty cycle of the phase leg with M1 and M2, and M1 is the primary switch.


Components in Electronics 12VIN /24VOUT


Max IOUT Effi ciency at IMAX Thermal at IMAX


12VIN/36VOUT Effi ciency at IMAX


Max IOUT Effi ciency at IMAX Thermal at IMAX


LTM4712 6A


96.9% 69o


C 4A 96.1% C


96.1% 84o


Table 2. Boost mode thermal performance comparison, TA = 25°C, no forced cooling


Figure 8 illustrates an example circuit of the inverting confi guration, designed for a 24V input and –12V output, capable of delivering up to 10A of load current. Figure 9


presents the effi ciency curves obtained from bench testing.


In the inverting buck-boost converter, the output voltage may rise slightly above


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LTM4656 4A


95.7% 81o


C 94.8% C


2.5A 94.8% 89o


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