DEMO MANUAL DC2166A LTM4639 Low V 20A DC/DC IN Module Step-Down Regulator Description Demonstration circuit 2166A features the LTM 4639EY, on board boost circuit using LT1935 to provide control a 20A high efficiency, switch mode step-down power power to LTM4639 when V is less than 4.5V. LTM4639 IN Module regulator. The input voltage range is from has on board diode connected PNP transistors to monitor 2.375V to 7V. The output voltage range is 0.6V to 5.5V. its internal temperature. A temperature sensor LTC2997 Derating is necessary for certain V , V , frequency and converts the internal temperature to an analog voltage out- IN OUT thermal conditions. The DC2166A offers the TRACK/SS pin put. The LTM4639 data sheet must be read in conjunction allowing the user to program output tracking or soft-start with this demo manual prior to working on or modifying period. The board operates in continuous conduction mode demo circuit DC2166A. in heavy load conditions. For high efficiency at low load Design files for this circuit board are available at currents, the MODE jumper (JP3) selects pulse-skipping DEMO MANUAL DC2166A p s PARAMETER CONDITIONS/NOTES VALUE Input Voltage Range 2.375V to 7V Output Voltages 1.0V, 1.2V, 1.5V, 1.8V 1.5% Maximum Continuous Output Current Derating is necessary for certain operating conditions. 20ADC See data sheet for details. Operating Frequency 500kHz Efficiency V = 3.3V, I = 20A 83.2% (V = 1.0V) (Figure 2) IN OUT OUT1 85.3% (V = 1.2V) (Figure 2) OUT1 87.7% (V = 1.5V) (Figure 2) OUT1 89.1% (V = 1.8V) (Figure 2) OUT1 Load Transient V = 3.3V, V = 1.0V, I = 0A to 10A 156mV (Figure 4) IN OUT STEP Quick s p D Demonstration circuit DC2166A is an easy way to evalu- 5. (Optional) For optional load transient test, apply an ate the performance of the LTM4639EY. Please refer to adjustable pulse signal between IOSTEP CLK and GND Figure 1 for proper measurement equipment setup and test points. The pulse amplitude sets the load step cur- follow the procedure below: rent amplitude. Keep the pulse width short (<1ms) and pulse duty cycle low (<5%) to limit the thermal stress 1. Place jumpers in the following positions for a typical on the load transient circuit. application: 6. (Optional) LTM4639 can be synchronized to an external V OUT clock signal. Place the JP3 jumper on EXTCLK and apply RUN TRACK/SS MODE SELECT CPWR SELECT a clock signal (0V to 5V, square wave) on the CLKIN ON SOFT-START CCM 1.0V BOOST test point. 7. (Optional) The outputs of LTM4639 can track another 2. With power off, connect the input power supply, load supply by setting JP1 to EXT. TRACK. If tracking external and meters as shown in Figure 1. Preset the load to 0A voltage is selected, the corresponding test point TRACK and V supply to 3.3V. IN need to be connected to a valid voltage signal. 3. Turn on the power supply at the input. The output volt- age should be 1.0V 1.5% (0.985V to 1.015V). 4. Vary the input voltage from 2.375V to 7V and adjust the load current from 0A to 20A. Observe the output voltage regulation, ripple voltage, efficiency, and other parameters. dc2166af 2 ure roce tart ummary erformance