HV100 Demo Board HV100DB1 3-Pin Hotswap Controller Introduction Specifications The Supertex HV100DB1 demo board contains all necessay circuitry to demonstrate the features of the HV100 hotswap controller. Intended primarily as a negative hotswap controller, the HV100 controls the negative supply path. Input Voltage 10V to 72V Peak Inrush Limit 1.4A typ Max Short Circuit Current1 Included on board is a 100µF capacitor (C3) to provide a capacitive load for testing. Additional capacitance may be connected to the VOUT terminals. Or the 100µF may be removed altogether The board may be modified to meet custom requirements. Instructions are provided on the next page for modifications. 4A typ Circuit Breaker Response Time1 1ms typ Auto Retry 2.5s typ On Resistance Undervoltage Trip 1 210mW_ max 37V on, 34V off During inrush limiting Board Layout and Connections +OUT VPP IN VPP OUT VIN Current Probe C2 C1 R2 alt Q1 VNN IN U1 + C3 DRAIN GATE VOUT Power Supply or Load -OUT Q1 R1 VIN VOUT Connect the supply voltage to these terminals. Supply voltage may range from 10 volts to 72 volts. Connect the power supply or other load to these terminals. VOUT+ is connected to VIN+, it is VOUT– that is switched. A high source impedance may cause oscillations when the input voltage is near the undervoltage trip point. A high source impedance results in a large voltage drop when loaded, causing undervoltage lockout to kick in, disconnecting the load. With the load removed, input voltage rises, causing undervoltage to release and reconnecting the load. The cycle repeats, resulting in oscillations. Source impedance must be less than the following to avoid oscillations: Application of a DC load during start-up and/or additional load capacitance extends the time inrush limiting is active. If this time exceeds 100ms, the HV100 shuts off, retrying 2.5s later. For this reason, DC load at start-up should be less than 900mA. Note that DC start-up load limitation decreases with added load capacitance. RSOURCE = Note that the circuit breaker functions during inrush only. 1.5V I LOAD 01/21/02 Supertex Inc. does not recommend the use of its products in life support applications and will not knowingly sell its products for use in such applications unless it receives an adequate "products liability indemnification insurance agreement." Supertex does not assume responsibility for use of devices described and limits its liability to the replacement of devices determined to be defective due to 1 workmanship. No responsibility is assumed for possible omissions or inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications, refer to the Supertex website: http://www.supertex.com. For complete liability information on all Supertex products, refer to the most current databook or to the Legal/Disclaimer page on the Supertex website. HV100 Demo Board HV100 Demo Board Schematic VPP OUT VPP IN OUT+ VPP HV100 VNN GATE C2 not used VNN IN current probe C1 not used GATE C3 100µF R2 not used OUTQ1 IRFR120N R1 0Ω A very high dV/dt on the input can overload the HV100’s internal gate clamp, causing turn-on transients. A capacitor in the C2 position may be used to clamp the gate, preventing the transients. A 1nF value is usually adequate. Voltage rating should be 16 volts. DRAIN To reduce peak inrush current, a capacitor from gate to drain (C1) may be employed. A resistor (R2) is also needed in this configuration for loop stability. Please refer to the HV100 data sheet for further information. Note: When making positive-ground measurements, scope probe loading on the GATE pin may interfere with normal operation. To observe gate voltages, use negative-ground measurements. To limit short-at-turn-on current, zero-ohm resistor R1 may be replaced with a low value resistor. This resistor causes a voltage drop that tends to cancel-out the applied gate voltage, thus limiting drain current. 01/21/02 ©2001 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited. 2 1235 Bordeaux Drive, Sunnyvale, CA 94089 TEL: (408) 744-0100 • FAX: (408) 222-4895 www.supertex.com