DC2466A Analog Devices

DEMO MANUAL DC2466A LTC3246EMSE Wide V Range Buck-Boost IN Charge Pump with Watchdog Timer DESCRIPTION Demonstration circuit 2466A is a buck-boost 500mA The LTC3246 data sheet gives a complete description of charge pump with pin selectable output voltages and the device, operation and application information. The includes a watchdog timer featuring the LTC 3246EMSE. data sheet must be read in conjunction with this demo The LTC3246 operates with a wide input voltage range manual. from 2.7V to 38V and is engineered for diagnostic cov- Design files for this circuit board are available at erage for ISO 262262 compliant systems. The wide V IN DEMO MANUAL DC2466A TYPICAL APPLICATIONS Regulated 5V Output with Pushbutton Reset Output Voltage vs Input Voltage 2.2F 5.20 5.15 V = 5V OUT + I UP TO 500mA OUT 5.10 C C V = 3V TO 40V V V IN IN OUT 5.05 10F 1F SEL2 500k 500k 5.00 SEL1 RST LTC3246 C 4.95 BIAS WDI 10F 4.90 RT 4.85 WT RSTI I = 50mA OUT GND I = 500mA OUT DC2466a TA01a 4.80 RESET 0 2 4 6 8 10 12 14 16 V (V) PIN NOT USED IN THIS CIRCUIT: OUTS/ADJ IN DC2466a TA01b QUICK START PROCEDURE Refer to Figure 1 for the proper measurement equipment 6. Turn off PS1 and set LD1 to 0A. setup and jumper settings and follow the procedure below. 7. Set the SEL1 jumper, JP1, to the LO position. NOTE: When measuring the input or output voltage ripple, 8. Set PS1 to 14V and then turn on. care must be taken to avoid a long ground lead on the 9. Slowly increase LD1 to 500mA and observe VOUT is oscilloscope probe. Measure the input or output voltage regulating at 5V and that the input current is about ripple by touching the probe tip directly across the V or IN of the output current. The LTC3246 is in 2:1 mode. V and GND terminals. See Figure 2 for proper scope OUT probe technique. 10. Decrease PS1 to 9V and observe that VOUT is 5V and the input current is about equal to the output current. 1. Make sure the jumper settings are as follows: The LTC3246 is in 1:1 mode. JP1: SEL1 is on the HI position 11. Decrease PS1 to 3.3V and observe that VOUT is 5V JP2: SEL2 is on the HI position and the input current is about 2x the output current. JP3: CRT is on the INT position The LTC3246 is in 1:2 mode. JP4: CWT is on the DIS position 12. Set PS1 to 14V and then turn off LD1. JP5: RSTI is on the HI position 13. Short the RSTI turret to GND and observe that the voltage on the RST turret is near 0V. 2. Set PS1 to 14V and then turn on. 14. Remove the short on the RSTI turret and observe with 3. Slowly increase LD1 to 500mA and observe VOUT is an oscilloscope that the voltage on the RST turret regulating at 3.3V and that the input current is about returns to about VOUT. of the output current. The LTC3246 is in 2:1 mode. Note: The reset time can be adjusted by setting the 4. Decrease PS1 to 5V and observe that VOUT is 3.3V and CRT jumper, JP3, to the EXT position and using exter- the input current is about equal to the output current. nal capacitors if desired. The external CRT capaci- The LTC3246 is in 1:1 mode. tor, C9, is populated with a 2.2nF to match the times 5. Decrease PS1 to 3V and observe that VOUT is 3.3V and referenced in the data sheet. The reset time can the input current is about 2x the output current. The be increased by placing a parallel capacitor on the LTC3246 is in 1:2 mode. dc2466af 2 V (V) OUT