Key Specs
| Spec | Value | Condition | Source |
|---|---|---|---|
| Current Startup | 12 mA | Digi-Key | |
| Mode | Current Controlled Frequency Foldback (CCFF), Critical Conduction (CRM) | Digi-Key | |
| Mounting Type | Surface Mount | Digi-Key | |
| Operating Temperature Range | -40°C ~ 125°C | Digi-Key | |
| Package Case | 16-SOIC (0.154”, 3.90mm Width), 15 Leads | Digi-Key | |
| Supplier Device Package | 16-SOIC | Digi-Key | |
| Switching Frequency (Typ) | 26kHz | Digi-Key | |
| Voltage Supply | 9.5V ~ 28V | Digi-Key |
When To Use
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12V automotive accessory from 14V battery @ 1.5A: The 9.5V to 28V input range fits a 14V nominal automotive battery voltage with load-dump transients safely within spec. Using a synchronous buck controller here risks shoot-through if the external MOSFET gate drive is not carefully managed, whereas this part’s CRM and current-controlled frequency foldback prevents excessive conduction losses and runaway under load.
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24V industrial sensor supply → 5V @ 0.5A: The fixed 26kHz switching frequency and current-controlled frequency foldback mode ensure stable operation with moderate EMI and predictable thermal dissipation. A high-frequency buck controller would cause excessive switching losses and EMI in this environment, potentially triggering system-level interference and thermal stress.
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Battery-powered LED driver from 20V nominal input @ 350mA: The low startup current of 12mA reduces power waste during startup and transient conditions. Linear regulators here would dissipate excessive heat, causing thermal shutdown, while a multi-phase buck controller is overkill for this modest current and would add unnecessary complexity.
When Not To Use
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>3A output load for server VRM: The limited current capability implied by the 12mA startup current and typical CRM mode disqualifies this part. Use a multi-phase buck controller to handle high output currents with balanced thermal and current sharing.
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Battery-powered sensor needing μA sleep current: The minimum 12mA startup current is too high for low standby power budgets. Use a low-IQ PFM buck designed for ultra-low quiescent current to maximize battery life.
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Input voltage near output voltage (<1V difference) noise-sensitive analog supply: The switching frequency and topology make it unsuitable for tight dropout and low noise. Use an LDO regulator to achieve low output noise and clean regulation in tight headroom conditions.
Application Notes
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The switching node (SW) pin requires a compact, low-inductance copper area to minimize EMI and voltage ringing; avoid long traces or loops that increase parasitic inductance.
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Pins 3, 4, and the control and feedback inputs pin are noise-sensitive and must be routed away from SW and gate drive signals; use guard traces connected to ground to shield these nodes.
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The package’s 16-SOIC footprint (3.90mm width) demands careful thermal relief on the PCB copper to maintain junction temperature within limits, especially since the part operates up to 125°C.
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External component placement for the current sensing resistor must be as close as possible to the IC pins to ensure accurate current measurement and prevent false triggering of frequency foldback.
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The internal current-controlled frequency foldback mode relies on stable sensing resistor values; temperature coefficients and PCB heating can shift this threshold, so low-TCR resistors and appropriate thermal layout are recommended.
Gotchas
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[Startup current underestimation]: Designers often assume the 12mA startup current applies only momentarily; however, in CRM mode, the IC maintains this bias continuously during switching, increasing power dissipation and potentially raising junction temperature beyond initial estimates.
What happens: Thermal stress causes premature device aging or unexpected shutdown in continuous operation.
Fix: Measure quiescent current under expected load conditions and verify thermal design margins with real board layouts. -
[Incorrect feedback loop compensation]: Using output capacitors with too low ESR can destabilize the control loop due to the CRM mode’s interaction with the current-controlled frequency foldback, causing output voltage oscillations and noise.
What happens: Output voltage ripple increases, periodic dropouts appear on load, and EMI spikes can occur.
Fix: Select output capacitors with ESR in the recommended range or add a small series resistor to ensure loop stability. -
[SW node ringing causing false current sensing]: Excessive PCB parasitic inductance on the SW node leads to voltage spikes that couple into the current sensing input, triggering premature foldback or erratic switching frequency.
What happens: Unexpected frequency jitter, output voltage instability, and audible noise.
Fix: Minimize SW loop area, use proper ground returns, and place current sense resistor close to the IC pins. -
[Startup under no load]: The device requires a minimum load to maintain stable operation due to the current foldback mode; starting with no or very light load can cause the converter to fail to start switching or exhibit intermittent pulses.
What happens: Output voltage never reaches regulation, or starts with bursts and then stops.
Fix: Add a minimum load resistor or ensure load current exceeds the internal threshold during startup.