LP38843 - 3A Ultra-Low Dropout LDO with Enable | TI
MPN: LP38843 β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.15 | $3.15 |
| 10 | $2.83 | $28.30 |
| 100 | $2.52 | $252.00 |
| 500 | $2.27 | $1,135.00 |
| 1,000 | $2.04 | $2,040.00 |
Drop-in alternatives for LP38843 β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
LP38842
β Drop-Inπ Reference alternative (not in catalog)
LP38841
β Drop-Inπ Reference alternative (not in catalog)
LP38843S-1.2/NOPB
β Drop-Inπ Reference alternative (not in catalog)
LP38843 Maximum Ratings & Electrical Characteristics
| Output Current | 3 A |
| Output Type | Positive Fixed |
| Number of Outputs | 1 |
| Minimum Input Voltage (Vin) | 1.01 V |
| Dropout Voltage | Ultra-low (N-MOS, see datasheet for per-VOUT value) [DATA_NEEDED: exact dropout voltage] |
| Pass Element | N-MOS, CMOS process |
| Bias Supply (Vbias) | [DATA_NEEDED: Vbias voltage range] |
| Enable Pin | Yes |
| Output Capacitor | Stable with ceramic output capacitors |
| Output Voltage Options | 1.2 V, 1.5 V fixed |
| Package | TO-220-5 (NDZ), TO-263 (KTT) |
| Mounting Type | Through Hole (TO-220-5) / Surface Mount (TO-263) |
| Operating Temperature | [DATA_NEEDED: operating temperature range] |
| RoHS Status | Compliant (NOPB / non-Pb versions) |
| Transient Response | Fast response, maintains regulation at full load steps |
LP38843 Pin Configuration
| Pin 1 | Vbias β Bias supply input, drives N-MOS pass transistor gate |
| Pin 2 | GND β Ground |
| Pin 3 | EN β Enable input (LP38843); regulate when active |
| Pin 4 | Vin β Power input supplying the load |
| Pin 5 | Vout β Regulated output voltage |
Safe Operating Area (SOA) & Thermal Characteristics
No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.
Typical Applications
LP38843 is suitable for 6 applications: DSP Core Power Supply, Point-of-Load Regulation, Post-Regulation of Switching Converters, FPGA and Processor I/O Rails, Industrial Control Boards, Test and Measurement Equipment.
DSP Core Power Supply
DSPs such as the TMS320C6000 family require tightly regulated 1.2V or 1.5V core rails that can step from milliamps to amps in nanoseconds. The LP38843 delivers up to 3A with fast transient response, holding the core voltage within spec during load steps, and its ultra-low dropout allows use from a low intermediate rail. Placed as a point-of-load regulator next to the DSP with ceramic output capacitors, it minimizes loop inductance and switching noise.
Recommended
Point-of-Load Regulation
On dense telecom and networking cards, multiple low-voltage high-current rails are best served by local point-of-load regulators rather than centralized supplies. The LP38843's 1.01V minimum input and 3A capability make it an efficient final stage fed by a downstream bulk rail, cutting I-R drop and improving transient performance at each load. Its enable pin allows per-rail sequencing under supervisor control, and ceramic-capacitor stability keeps the BOM compact.
Recommended
Post-Regulation of Switching Converters
Switching converters leave millivolts of ripple and switching spikes on their outputs. Placing the LP38843 after a buck converter strips this ripple before it reaches sensitive analog or RF silicon, because its N-MOS LDO topology provides high ripple rejection at the load point. The ultra-low dropout means only a small headroom is needed, so the efficiency penalty of the linear stage stays small even at 3A loads.
Recommended
FPGA and Processor I/O Rails
FPGA I/O banks at 1.2V to 1.5V draw bursty currents during parallel bus switching. The LP38843's fast loop response handles these bursts without excessive bulk capacitance, and the enable pin supports power-up sequencing required by multi-rail FPGAs. With stable operation on ceramic output capacitors, one LP38843 can be placed per bank close to the load, minimizing PCB plane resistance effects on rail accuracy.
Recommended
Industrial Control Boards
Industrial controllers combining 24V bus power with low-voltage digital logic use an intermediate buck rail followed by LP38843 point-of-load regulators for 1.2V/1.5V logic and DSP cores. The TO-263 package with its exposed tab allows straightforward thermal management on standard FR4, and the wide availability of the TI LP388x family simplifies long-term sourcing for multi-year production runs in factory automation equipment.
Recommended
Test and Measurement Equipment
Bench instruments and ATE boards need clean, accurately fixed low-voltage rails for ADC/DAC and logic supplies. The LP38843 provides a fixed, low-noise 1.2V or 1.5V rail with 3A headroom and no switching artifacts, making it suitable as a final analog-friendly stage after a switching pre-regulator. Its enable pin lets the instrument controller gate individual rails during self-test and calibration routines.
Recommended
Recommended Products Summary
Engineering reference data for LP38843 β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LP38842 | LP38841 | TPS7A8300QRGRRQ1 |
|---|---|---|---|---|
| Package | TO-220-5 (NDZ) / TO-263 (KTT) | TO-220-5 / TO-263 - same | TO-220-5 / TO-263 - same | VQFN-20 (RGR) - different |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Output Current | 3 A | 3 A | 3 A | 2 A |
| Output Type | Fixed 1.2V / 1.5V | Fixed 1.2V / 1.5V / 1.8V options | Adjustable | Adjustable (0.8V - 5.17V) |
| Enable Pin | Yes | No | No | Yes |
| Minimum Input Voltage | 1.01 V | Approx. same (family spec) [DATA_NEEDED] | Approx. same (family spec) [DATA_NEEDED] | 1.4 V |
| Ceramic Capacitor Stability | Yes | Yes | Yes | Yes |
| Dropout Voltage | Ultra-low (N-MOS) [DATA_NEEDED: exact mV] | Ultra-low (same die family) [DATA_NEEDED] | Ultra-low (same die family) [DATA_NEEDED] | ~210 mV at 2A [DATA_NEEDED] |
Key Differentiators
- Enable pin for rail sequencing (vs LP38842)
- Adjustable output flexibility (vs LP38841)
- Lower minimum Vin for lowest-core rails (vs TPS7A8300QRGRRQ1)
Design Notes
The LP38843 requires both Vbias and Vin. Vbias (gate-drive supply, typically 2.7V-5.5V class) must be established for the N-MOS pass element to turn on; sequence Vbias before or simultaneously with Vin, or ensure EN is asserted only after both supplies are valid. Connect Vbias to an always-on 3.3V or 5V rail and use the EN pin for output sequencing control.
At 3A with, for example, 1.8V in and 1.5V out, dissipation is about 0.9W; from a 2.5V rail it rises to 3W. The TO-220-5 tab and TO-263 exposed pad must be soldered to adequate copper area - at least 1 square inch of 1oz copper or an equivalent heatsink for continuous full-load operation. Verify junction temperature against the datasheet derating curve at worst-case ambient.
The LP38843 is stable with ceramic output capacitors, but place the output capacitor within a few millimeters of the Vout pin to minimize parasitic inductance that can degrade transient response and loop stability. Use a low-ESR 10uF-class ceramic on the output and appropriate input capacitance on both Vin and Vbias per the datasheet typical application circuit. Keep the ground pin return path low-impedance.
Compliance Information
NOPB suffix versions (e.g., LP38843T-1.5/NOPB) are lead-free/RoHS compliant per DigiKey listings. This is not an automotive AEC-Q100 qualified part - verify on TI quality pages if automotive use is considered.
