POWER
gain operation over the output range, resulting in virtually constant output noise independent of the output voltage. Figure 3 shows the radiated EMI performance.
Multiphase Parallel Operation for Higher Output Current
Two or more devices may be paralleled to supply a higher current. Figure 4 shows an example: two µModule regulators are in parallel to produce up to 16A load current. In the example, the CLKOUT signal is connected to the SYNC pin of the following IC to line up both the frequency and the phase of the paralleled system. The two paralleled regulators are running at 180° out of phase, with the PHMODE pin tied to the ground. Excellent current sharing is achieved with the current-mode control architecture by connecting the compensation pins together. The SET pins of the paralleled devices are tied together with only one SET resistor.
Conclusion Fig 3: Radiated EMI performance of the LTM4702
AGND). The SET pin sources a precision 100µA current that flows through an external resistor connected between the SET pin and GND. The regulator output voltage will strictly follow the SET pin voltage, which is determined by ISET ? RSET. Using a SET pin bypass capacitor reduces sensitivity to any parasitic coupling of voltage spikes onto the SET pin. A SET pin bypass capacitor also soft starts the output and limits inrush current. The efficiency vs. load current curves are shown in Figure 2. In the example circuit, the SYNC pin is tied to GND for pulse-skipping mode, improving efficiency at light loads. This device can also operate in forced continuous mode (FCM) for fast transient response and full frequency operation over a wide load range. To enable FCM, tie the SYNC pin to INTVCC or >3V, or float the SYNC pin.
Driving the SYNC pin with a clock source can synchronise the regulator to an external clock. The device may be synchronised over a 300kHz to 3MHz range. The regulator will run in FCM while synchronised to an external clock. The LTM4702 features a programmable power good by using a single resistor across the VOUT pin and the PGSET pin. The power good output (PG) will be low when the output voltage is outside of the ±7.5% regulation window. The IC also has other user-friendly features, including enable/shutdown control, a selection of internal loop compensation or external loop compensation, and an internal temperature monitor.
Ultralow Noise Silent Switcher The Silent Switcher family is engineered with innovative design and packaging techniques to offer high efficiency while reducing EMI. This unique approach makes these regulators less susceptible to PCB layout variations, resulting in simplified designs and enhanced performance. The LTM4702 has an ultralow noise architecture to obtain exceptional low frequency (<100kHz) output noise. A single resistor sets the output voltage, providing unity
The LTM4702 is a complete 8A step-down Silent Switcher µModule regulator. It can provide a precisely regulated output voltage programmable via one external resistor from 0.3V to 5.7V. Low EMI and low noise features make it ideal for high current and noise- sensitive applications, such as telecom/ datacom systems, RF power supplies, and high speed/high precision data converter applications.
With the compact size, high efficiency, and low external component count of this µModule regulator, users will save significant board space and design time. Analog Devices:
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Fig 4: The LTM4702 2-phase, 1V, 16A step-down power supply MAY 2025 | ELECTRONICS TODAY 13
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