Current Limit

Threshold

Io

Normal Operation

Current Limited

Low Load Current

High Load Current

'I

LM5010A

LM5010A-Q1

www.ti.com

SNVS376E – OCTOBER 2005 – REVISED FEBRUARY 2013

Figure 10. Inductor Current - Current Limit Operation

N-Channel Buck Switch and Driver

The LM5010A integrates an N-Channel buck switch and associated floating high voltage gate driver. The peak

current through the buck switch should not exceed 2A, and the load current should not exceed 1.5A. The gate

driver circuit is powered by the external bootstrap capacitor between BST and SW (C4), which is recharged each

sufficient time during each cycle to recharge the bootstrap capacitor. A 0.022 µF ceramic capacitor is

recommended for C4.

Soft-start

The soft-start feature allows the regulator to gradually reach a steady state operating point, thereby reducing

(UVLO) an internal 11.5 µA current source charges the external capacitor (C6) at the SS pin to 2.5V (t2 in

Figure 7). The increasing SS voltage at the non-inverting input of the regulation comparator gradually increases

the output voltage from zero to the desired value. The soft-start feature keeps the load inductor current from

reaching the current limit threshold during start-up, thereby reducing inrush currents.

shutdown using the RON/SD pin.

Thermal Shutdown

The LM5010A should be operated below the Maximum Operating Junction Temperature rating. If the junction

temperature increases during a fault or abnormal operating condition, the internal Thermal Shutdown circuit

activates typically at 175°C. The Thermal Shutdown circuit reduces power dissipation by disabling the buck

switch and the on-timer. This feature helps prevent catastrophic failures from accidental device overheating.

When the junction temperature reduces below approximately 155°C (20°C typical hysteresis), normal operation

resumes.

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