DEMO MANUAL DC1733A LT3669 Industrial Transceiver with Integrated Step-Down Regulator and LDO DESCRIPTION Demonstration circuit 1733A is an industrial transceiver The board also provides various interfaces for line drivers with integrated step-down regulator and LDO featuring the and receivers. JP8 to JP11 set the signal sources or levels LT 3669. The board operates from 7.5V to 40V when JP7 is for TXEN1, TXEN2, TXD1 and TXD2. + set to L . When the JP7 is set to RES, the minimum input The LT3669 data sheet gives complete descriptions of the voltage is 16.5V. The board withstands transients up to part, operation and application information. The data sheet 60V. The step-down regulator output is 5V. The LDO output must be read in conjunction with this quick start guide for is 3.3V. There are two assembly versions. DC1733A-A is working on or modifying the demo circuit 1733A. for the LT3669 and DC1733A-B is for the LT3669-2. The Design files for this circuit board are available. difference is the LT3669 has an integrated catch diode. Call the LTC Factory. The LT3669-2 requires an external catch diode. Table 1 shows the differences between the two versions. L, LTC, LTM, LT, Burst Mode are registered trademarks of Linear Technology Corporation. Other product names may be trademarks of the companies that manufacture the products.. PERFORMANCE SUMMARY Specifications are at T = 25C A SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS + L Input Supply 7.5 40 V V Output Voltage Step-Down Regulator 4.75 5 5.25 V BUCK V Output Voltage LDO 3.135 3.3 3.465 V LDO I Maximum Buck Output Current LT3669, Step-Down Regulator V = 5V 100 mA BUCK BUCK LT3669-2, Step-Down Regulator V = 5V 300 mA BUCK I Maximum LDO Output Current LT3669, VLDO = 3.3V 100 mA LDO LT3669-2, VLDO = 3.3V 150 mA FSW Switching Frequency 600 kHz + EFF Efficiency LT3669, L = 12V, V = 5V, I = 100mA 65 % BUCK BUCK + LT3669-2, L = 12V, V = 5V, I = 300mA 76 % BUCK BUCK TRST Reset Timeout Period C5=100nF 12.5 ms Table 1. Version Table ASSY TYPE U1 I I C8 C9 D6 L1 LDO BUCK DC1733A-A LT3669EUFD 0.1A 0.1A 10F 0.1F OPEN 82H, CDRH4D22HPNP-820MC DC1733A-B LT3669EUFD-2 0.15A 0.3A 22F 0.22F DFLS160 33H, CDRH50D28RNP-330MC dc1733af 1DEMO MANUAL DC1733A QUICK START PROCEDURE Demonstration circuit 1733A is easy to set up to evaluate 5. Turn on the power at the input. the performance of the LT3669 or the LT3669-2. Refer to 6. Check for the proper output voltages. Figure 1 for proper measurement equipment setup and NOTE. If there is no output, temporarily disconnect follow the procedure below: the load to make sure that the load is not set too high NOTE. When measuring the input or output voltage ripple, or is shorted. care must be taken to avoid a long ground lead on the 7. Once the proper output voltage is established, adjust oscilloscope probe. Measure the input or output voltage the loads within the operating range and observe the ripple by touching the probe tip directly across the terminals output voltage regulation, ripple voltage, efficiency and of the input or output capacitors. See Figure 2 for proper other parameters. scope probe technique. 8. To test driver and receiver functions, use JP8 to JP11 1. Place jumpers in the proper positions. to set up the proper signal sources or levels for TXEN1, 2. With power off, connect an input power supply to TXEN2, TXD1, and TXD2. + L and L /GND. The input supply can be a bench 9. Set up or monitor other signals as needed. power supply or can be from the respective output from a master controller. 10. Once the above signals are set up, observe drivers outputs and receivers inputs and outputs. 3. With power off, connect the load to V and GND. BUCK 4. With power off, connect another load to V and GND. LDO dc1733af 2