DEMO MANUAL DC1555B LTC4365: High Voltage UV, OV and Reverse Supply Protection Controller Description Demonstration circuit DC1555B is intended to demonstrate or when the input voltage is outside of the UV or OV level. the performance of the LTC4365 High Voltage Undervoltage The LTC4365 can withstand DC voltages between 40V (UV), Overvoltage (OV) and Reverse Supply Protection and 60V and has a valid operating range of 2.5V to 34V. Controller. The DC1555B includes the LTC4365 Controller, two back- The LTC4365 protects circuits from input voltages that may to-back connected power MOSFETs, three jumpers and be too high, too low or negative. It operates by controlling three LEDs to indicate the input and output voltages and the gates of two back-to-back connected MOSFETs to keep the FAULT pin signal. the output in a safe range. The OV and UV protection levels Design files for this circuit board are available at are adjusted by resistive dividers at the OV and UV pins. DEMO MANUAL DC1555B Ao ting p The LTC4365 monitors the input rail voltage and discon- protection circuit automatically isolates the load from nects downstream circuits when the input voltage is too negative input voltages. low, too high or negative. The LTC4365 provides accurate During normal operation, a high voltage charge pump overvoltage and undervoltage comparators to ensure that enhances the gate of external N-channel power MOSFETs. power is applied to the system only if the input supply The LTC4365 consumes 10A during shutdown and 125A is within the allowable voltage window. Reverse supply while operating. Uq ick stArt proceDU Demonstration circuit 1555B is easy to set up to evaluate Undervoltage/Overvoltage Test (Figure 1b) the performance of the LTC4365. Refer to Figures 1a and 8) Reverse the polarity of power supply connection across 1b for proper measurement equipment setup and follow V to GND (connect positive rail to V and negative IN IN the procedure below. rail to GND). Note that the circuit on the DC1555B is optimized for 12V 9) Ramp supply up to 30V and verify green V LED, red IN operation The Si4230 FET limits overvoltage and reverse FAULT LED, green V LED, and V according to OUT OUT voltage to 30V and 30V, respectively. Refer to the LTC4365 Table 1 within the various voltage ranges. data sheet for applications optimized for other voltages. 10) Ramp supply down from 30V down to 0V and verify Reverse Voltage Tests (Figure 1a) green V LED, red FAULT LED, green V LED, and IN OUT V according to Table 1. OUT 1) Set JP1 to EN. 11) Repeat steps 9 and 10 with 8A load connected across 2) Set JP2 and JP3 to CONNECT LED. V and GND. OUT 3) Connect a power supply across V and GND in negative IN Table 1 configuration (connect positive rail to GND and negative V V V LED V LED FAULT LED IN OUT IN OUT rail to V ). IN 0V to 5.77V = 0V Off/Dim/On Off On 4) Connect voltmeters at the input and output and ammeter 6.56V to 13.51V = V On On Off IN in series with supply. 15.47V to 30V = 0V On Off On 5) Ramp supply down to 30V (referenced to GND). Jumper Test 6) Verify output voltage is between 0V and 0.5V, all LEDs are off, and input current is <1.8mA. (FET leakage or 12) Remove load and set supply to 9V. other board leakage paths can pull V slightly nega- OUT 13) Move jumpers and verify LEDs according to Table 2. tive, but it will be clamped by the internal protection diode.) Table 2 JP1 JP2/JP3 VIN LED VOUT LED 7) Ramp supply back to 0V. EN CONNECT LED On On DIS CONNECT LED On Off EN Open Off Off dc1555bfa 2 re rinciples per