Key Specs

SpecValueConditionSource
Mounting TypeSurface MountDigi-Key
Number Of Outputs3Digi-Key
Operating Temperature Range-40°C ~ 125°C (TA)Digi-Key
Package Case8-SOIC (0.154”, 3.90mm Width) Exposed PadDigi-Key
Supplier Device Package8-SOIC-EPDigi-Key
Switching Frequency (Typ)350kHzDigi-Key
TopologyStep-Down (Buck) (1), Linear (LDO) (2)Digi-Key
Voltage Current Output 11.25V ~ 72V, 500mADigi-Key
Voltage Current Output 25V, 100mADigi-Key
Voltage Current Output 33.3V, 50mADigi-Key
Voltage Supply4.5V ~ 72VDigi-Key
W Led DriverNoDigi-Key
W SequencerNoDigi-Key
W SupervisorNoDigi-Key

When To Use

  1. 43V industrial/24V bus → 3.8V @ 1000A: The 72V maximum input voltage rating combined with a continuous output current capability of up to 1A suits industrial and 24V bus rails well. Using a synchronous buck controller with lower voltage rating risks shoot-through or damage at voltage spikes common on automotive or industrial lines.

  2. 22V automotive/battery rail → 2.5V @ 500.0A: The wide input voltage range from 4.5V to 72V and integrated 0.6Ω high-side MOSFET enable robust operation from automotive battery rails with transient voltage spikes. A linear regulator would dissipate excessive power, causing thermal runaway above 125°C ambient.

  3. 4.5V–72V wide-input supply → 1.2V–3.8V @ 750.0A: The 350kHz switching frequency and built-in current limit of 0.82A provide stable buck regulation for moderate loads across a wide input range. A low-IQ PFM buck would not handle this continuous load current reliably, resulting in voltage collapse under heavy load.

When Not To Use

  1. Output current > 1A continuous: The maximum continuous output current rating is 1000mA (typ), which limits high-current applications. For currents beyond this, a multi-phase buck controller is necessary to distribute thermal and conduction losses.

  2. Quiescent current critical (μA sleep mode): Minimum quiescent current is 240µA (typ), which is too high for ultra-low power standby or coin cell systems. Use a low-IQ PFM buck to minimize battery drain in sleep.

  3. Switching frequency > 500kHz needed: The maximum switching frequency is 1000kHz, but typical operation is 350kHz and foldback frequency minimum is 90kHz, which may limit compact inductor choices at higher frequencies. For applications requiring >500kHz switching, choose a high-frequency buck controller.

Application Notes

IC dissipates ≈274.4W at Vin=72V→Vout=2.5V @ 500.0A (η≈82%). This is IC loss only — the catch diode dissipates additional power. At elevated ambient, a heatsink is required for sustained operation above ~1.5A.

Minimum External Components

Catch diode — Schottky, Vr ≥ 72V, If ≥ 1000A Selection: Schottky forward recovery < 10ns vs 200–500ns for silicon. At 1000kHz (period = 1.0µs), a 500ns-recovery diode is off for only 0.5µs before the next switch-on — it never fully turns off. Failure mode: Standard silicon rectifier: 200–500ns reverse recovery at 1000kHz causes shoot-through current spikes every cycle — IC switch current exceeds rating, causing thermal runaway or immediate failure.

Output inductor — 22µH Selection: Isat ≥ 1250.0A (peak current at max load). DCR < 100mΩ to limit conduction loss. At Vin=38V→Vout=3.8V: range is 10–22µH (30%→15% current ripple). Use 22µH for good regulation; 10µH acceptable if BOM cost is critical. Isat must be ≥ 1250.0A — under-sizing Isat is the leading cause of field failures: the inductor saturates under peak current, spiking IC switch current beyond its rating. Failure mode: Isat below peak inductor current → core saturates → effective inductance collapses → switch current spikes beyond IC rating → thermal shutdown or permanent failure.

Input capacitor — ≥100µF electrolytic + 100nF ceramic (parallel) Selection: Electrolytic handles bulk ripple current; ceramic bypasses switching spikes. Voltage rating ≥ 72V with 20% margin. Failure mode: Insufficient input capacitance: supply rail collapses during switch-on current demand → output droops → erratic regulation and potential latch-up.

Output capacitor — ≥100µF electrolytic Selection: ESR < 200mΩ to keep output ripple below 50mVpp. Voltage rating ≥ 3V. Failure mode: High-ESR electrolytic: output ripple voltage = ESR × ΔIL. At 1A ripple and 500mΩ ESR → 500mVpp ripple — exceeds spec for virtually all loads.

Design Equations

Inductor sizing: At Vin=38V→Vout=3.8V: range is 10–22µH (30%→15% current ripple). Use 22µH for good regulation; 10µH acceptable if BOM cost is critical. Isat must be ≥ 1250.0A — under-sizing Isat is the leading cause of field failures: the inductor saturates under peak current, spiking IC switch current beyond its rating.

Gotchas

  1. Bootstrap voltage margin underestimated: Designers often assume the bootstrap capacitor voltage can drop below SW + 4V during startup or high load. This causes the high-side MOSFET to fail switching fully, resulting in distorted output voltage and increased losses. Fix by using a minimum 4V margin above SW with a proper bootstrap capacitor (X7R recommended) and verify with scope on BST-SW node during load transients.

  2. Insufficient output capacitance derating: The effective capacitance is specified as 50% lower than nominal. Using nominal capacitor values without derating causes loop instability or output voltage ripple under load. Measure capacitance under bias and temperature, and size output capacitors accordingly.

  3. Feedback voltage reference tolerance overlooked: The feedback voltage reference varies between 1.21V and 1.29V; designs that assume 1.25V fixed can set incorrect output voltages, causing regulation errors or premature hiccup mode triggering at loads near 30% setpoint. Include tolerance in FB resistor calculations and validate output voltage across temperature.

  4. ESD protection margin ignored during handling: The device has 2kV Human Body Model and 750V Charged Device Model ratings, but improper PCB handling or test procedures can cause latch-up or permanent damage, especially with sensitive exposed pad grounding. Always use ESD-safe handling and verify PCB grounding of the EP.