DEMO MANUAL DC2173A LTC3769 60V , Low I Synchronous IN Q Boost Controller DESCRIPTION Demonstration circuit DC2173A is a DC/DC synchronous 1. Directly from the input voltage boost converter featuring the LTC 3769 constant frequency 2. With the onboard low power bias supply current mode synchronous boost controller. The DC2173A 3. From the output voltage after start-up generates a 48V output voltage and provides 1.5A to 6A of output current. 4. Connecting to an external voltage source The 150kHz constant switching frequency operation results The onboard low power bias supply, based on LTC3630 in a small and efficient circuit. high efficiency, 65V 500mA synchronous step-down con- verter provides a stable 10V bias voltage, which increases This board operates over a wide 6V to 60V input volt- the overall efficiency at high input voltages. age range, has a 28A quiescent current during standby mode, and has a low power onboard bias supply along The DC2173A has a small circuit footprint and is a high with adjustable current limit. The user can select Burst performance, cost effective solution for telecom, automo- Mode operation, pulse skipping, or continuous conduction tive and Power over Ethernet applications. mode at light loads via an onbourd jumper. This converter Design files for this circuit board are available. provides high output voltage accuracy (typically 3%) over All registered trademarks and trademarks are the property of their respective owners. the entire load and temperature range. The DC2173A supports the following methods for biasing the LTC3769 onboard controller as follows: PERFORMANCE SUMMARY Specifications are at T = 25C A PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Input Supply Voltage IOUT = 0A to 1.5A 6 V Maximum Input Supply Voltage IOUT = 0A to 6.0A 60 V Output Voltage Range VIN = 6V to 36V, IOUT = 0A to 6.0A 48 3% V Typical Switching Frequency 150 kHz Typical Output Ripple (VOUT, 48V) I = 3A 200 mV LOAD Efficiency Typical (VOUT, 48V, V 12V) 96 % IN Rev B 1DEMO MANUAL DC2173A QUICK START PROCEDURE Demonstration circuit 2173A is easy to set up to evalu- To synchronize DC2173A with external clock insert jumper ate the performance of the LTC3769 controllers. Refer to MODE (JP1) in BURST position and apply clock signals Figure 1 for proper measurement equipment setup and to terminal CLKIN (E12). follow the procedure below: DC2173A Bias Circuits NOTE. When measuring the input or output voltage ripple, The demo board DC2173A shipped to be biased from the care must be taken to avoid a long ground lead on the internal low power bias supply based on LTC3630. Its oscilloscope probe. Measure the input or output voltage accomplished by populating R42, which connect output ripple by touching the probe tip directly across the VIN or of auxiliary power supply to VBIAS. If input or output VOUT and GND terminals. See Figure 2 for proper scope voltages are desired as a bias source, then resistors R31 probe technique. or R32 should be installed, instead of R42. Another pos- 1. Place jumper RUN (J2) in ON position, place jumper sibility is to use external power source, by connecting it MODE (JP1) in PULSE SKIP position. to terminal EXTVCC (E13). Please refer to LTC3769 data 2. Place jumper AUX (JP4) in ON position. sheet for details. On board low power converter can be disabled by placing jumper AUX (JP4) in OFF position. 3. Place jumper OVP (JP3) in OFF position. 4. With power off, connect the input power supply to VIN Converter Efficiency and GND. DC2173A exceeds 96% efficiency at 12V input voltage Turn the input power source on and slowly increase the generating 48V at 3A, see Figure 3. DC2173A delivers 3A input voltage. Be careful not to exceed 60V. of output current at 12V input however output current changes in a range from 1.5A to 6A depending on input NOTE: Make sure that the input voltage V does not ex- IN voltage. Figure 4 demonstrates maximum output current, ceed 60V. If higher operating voltage is required, power as function of input voltage, assuming 48V output voltage. components with higher voltage ratings should be used. All measurements were conducted at room temperature, 4. Check for the proper output voltage of 48V. If there natural convection cooling with no air flow. is no output, temporarily disconnect the load to make sure that the load is not set too high. 5. Once the proper output voltages are established, adjust the load within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. Rev B 2