UVLO (Under-Voltage Lockout) Circuit: Response Time <1μs

Q: What happens when UVLO activates in a gate driver?

When UVLO activates, the gate driver outputs are disabled (typically pulled low or high-impedance), preventing MOSFET/IGBT switching until voltage returns above the threshold with hysteresis.

Q: Can UVLO thresholds be adjusted?

Some gate driver ICs offer adjustable UVLO thresholds through external resistors, while most have fixed thresholds optimized for specific applications.

Q: Why is hysteresis important in UVLO circuits?

Hysteresis prevents oscillation and unstable operation when supply voltage fluctuates near the threshold, ensuring clean transitions between enabled and disabled states.

Component Specifications

Definition

An Under-Voltage Lockout (UVLO) circuit is a protection mechanism integrated into gate driver ICs that monitors the supply voltage and disables the output when voltage falls below a predetermined threshold. This prevents unreliable switching, shoot-through conditions, and damage to power semiconductors in applications like motor drives, inverters, and power supplies.

Working Principle

The UVLO circuit continuously compares the supply voltage against a reference voltage using a comparator. When VCC drops below the UVLO threshold, the comparator output triggers a latch or logic circuit that disables the gate driver outputs, putting them in a high-impedance or logic-low state. Hysteresis is typically incorporated to prevent oscillation near the threshold voltage.

Materials

Semiconductor silicon (CMOS/BiCMOS process), gold bonding wires, copper leadframes, epoxy molding compound

Technical Parameters

Parameter	Typical range	Notes & selection driver
Hysteresis	200-500mV typical
Response Time	<1μs
Supply Voltage Range	10V to 20V
Operating Temperature	-40°C to +125°C
UVLO Threshold Voltage	Typically 8-12V (adjustable in some ICs)

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 26262, IEC 60747, AEC-Q100

Parent Products

This component is used in the following industrial products

Gate Driver IC

An integrated circuit that provides the necessary voltage and current to drive the gate of power transistors (MOSFETs, IGBTs) in switching applications.

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Engineering Analysis

Risks & Mitigation

Insufficient UVLO threshold causing premature shutdown
Lack of hysteresis leading to output oscillation
Slow response time during voltage dips

FMEA Triads

Trigger: Power supply voltage drop below minimum operating level
Failure: Gate driver outputs disabled, system shutdown
Mitigation: Implement proper power supply design with adequate headroom and filtering

Trigger: UVLO comparator malfunction
Failure: False triggering or failure to trigger
Mitigation: Use ICs with built-in self-test features and follow manufacturer's layout guidelines

Trigger: Inadequate hysteresis design
Failure: Output oscillation during voltage transients
Mitigation: Select ICs with appropriate hysteresis or add external components as specified

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±5% on UVLO threshold voltage

Test Method

Power supply ramp testing with oscilloscope monitoring of enable/disable transitions

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

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Inspection readiness

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Manufacturers of UVLO (Under-Voltage Lockout) Circuit

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Frequently Asked Questions

What happens when UVLO activates in a gate driver?