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Texas Instruments LP38853S-ADJ/NOPB
- Part No.:
- LP38853S-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LP38853S-ADJ/NOPB.pdf
- Description:
- IC REG LIN POS ADJ 3A DDPAK
- Quantity:
- Payment:
- Shipping:
Inventory:3,143
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Product details
Overview
LP38853S-ADJ/NOPB from Texas Instruments is an adjustable 3-A fast-response LDO linear regulator with dual-input architecture (VIN and VBIAS), ±2% output voltage accuracy across –40°C to +125°C, 240 mV typical dropout at full load, and integrated soft-start and enable functions-designed for powering DSP/FPGA core rails and SMPS post-regulation in servers and graphics cards.
For engineers reviewing the LP38853S-ADJ/NOPB datasheet, LP38853S-ADJ/NOPB pinout, LP38853S-ADJ/NOPB application, or LP38853S-ADJ/NOPB equivalent, key selection considerations include VBIAS-dependent operating range (3–5.5 V), ADJ-pin feedback topology, SO PowerPAD™ thermal package compatibility, and soft-start capacitor programmability for inrush control.
Technical Context
The LP38853S-ADJ/NOPB uses a CMOS-based NMOS pass transistor architecture enabling ultra-low quiescent current (7–9 mA at 3 A) and wide bandwidth without requiring large external compensation. Its dual-rail operation separates high-current VIN (load path) from low-current VBIAS (control/gate-drive path), allowing stable regulation even when VIN approaches VOUT + 240 mV.
Functional blocks include undervoltage lockout (UVLO threshold 2.45 V with 150 mV hysteresis), precision 500-mV ADJ reference, internal soft-start timer (rSS = 13.5 kΩ), and thermal shutdown at 160°C. Enable logic features 1.25-V turn-on threshold with 100-mV hysteresis and internal 180-kΩ pull-up to VBIAS.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 3 A maximum continuous load-supports high-power digital ICs without derating at TJ ≤ 125°C in SO PowerPAD™ package. |
| Dropout Voltage | 240 mV typical at 3 A-enables operation with minimal VIN headroom, critical for low-voltage core rails (e.g., 0.8 V–1.8 V). |
| VOUT Accuracy | ±2% over –40°C to +125°C-ensures reliable voltage margining for ASIC/FPGA I/O and core supplies under thermal stress. |
| VBIAS Range | 3 V to 5.5 V-must be ≥4.5 V when VOUT > 1.2 V; enables use of standard 3.3 V/5 V bias rails while supporting ultra-low VIN operation. |
| Soft-Start Time | Programmable via CSS: tSS = CSS × 13.5 kΩ × 5-allows precise inrush current limiting (e.g., 675 µs with 10 nF) to prevent input rail sag. |
| PSRR @ 1 kHz | 70 dB (VIN), 58 dB (VBIAS)-rejects switching noise from upstream SMPS or noisy bias sources, preserving signal integrity in mixed-signal systems. |
| Thermal Resistance | RθJA = 48.4°C/W (SO PowerPAD™)-requires PCB copper pour under DAP for thermal management in high-power applications. |
Pinout & Package
LP38853S-ADJ/NOPB is packaged in an 8-pin SO PowerPAD™ (DDA) with exposed thermal pad (DAP) soldered to PCB ground plane for enhanced heat dissipation. The DAP is electrically connected to GND and serves as primary thermal interface.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN | Main power input | High-current path to NMOS pass transistor drain; must be decoupled with ≥10-µF ceramic capacitor close to pin. |
| OUT | Regulated output | Source of NMOS pass transistor; connects to load and output capacitor (COUT ≥10 µF ceramic); requires low-ESR layout. |
| ADJ | Feedback reference node | Connects to resistor divider (R1/R2) setting VOUT = 0.5 V × (1 + R1/R2); sensitive to noise-keep trace short and away from switching nodes. |
| GND | Analog/digital ground | Common return for IN, OUT, BIAS, EN, SS, and ADJ; must tie directly to DAP and system ground plane with multiple vias. |
| BIAS | Bias supply input | Powers internal reference, error amplifier, and gate driver; independent of IN-enables ultra-low VIN operation down to VOUT + 240 mV. |
| EN | Enable control input | Active-high logic (1.25 V threshold); internal 180-kΩ pull-up to VBIAS-leave open or tie to VBIAS if always-on operation required. |
| SS | Soft-start timing node | Controls VREF ramp rate via external CSS; must connect only to capacitor-no resistors or other components permitted on this net. |
| DAP | Thermal pad / GND | Exposed copper pad on bottom of package; electrically GND and thermally critical-requires ≥60% solder coverage and thermal vias to inner ground planes. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-rail input architecture | Separates high-current VIN (load path) from low-current VBIAS (control path), enabling stable regulation at VIN = VOUT + 240 mV while minimizing quiescent loss. |
| Adjustable output (0.8–1.8 V) | Set via precision 500-mV ADJ reference and external resistor divider-supports dynamic core voltage scaling for DSP/FPGA power management. |
| Stable with 10-µF ceramic COUT | No ESR requirements or additional compensation needed-reduces BOM count and simplifies layout versus traditional LDOs requiring tantalum or polymer caps. |
| Integrated soft-start | Programmable rise time via CSS eliminates inrush current spikes into large output capacitance-prevents input rail collapse during power-up sequencing. |
| Overtemperature & overcurrent protection | Thermal shutdown at 160°C with 10°C hysteresis and current limit ~5.8 A-protects device and system during fault conditions without external circuitry. |
Applications
| Server Core Voltage Regulation | FPGA I/O Supply |
|---|---|
Use Scenario: Regulating 1.2 V core voltage for multi-core Xeon processors in 1U rack servers with tight thermal constraints and strict ripple limits. IC Role / Device Role / Timing Role: Primary LDO post-regulator delivering clean, fast-transient 3-A core power; replaces less efficient discrete solutions with integrated soft-start and thermal protection. Use Value: 240-mV dropout enables use of lower-voltage intermediate bus (e.g., 1.45 V), reducing conduction losses by >15% versus higher-dropout alternatives. | Use Scenario: Providing 1.8 V I/O supply to Xilinx Kintex-7 FPGA banks where simultaneous switching noise (SSN) must be minimized. IC Role / Device Role / Timing Role: Low-noise, high-PSRR LDO supplying FPGA I/O banks; leverages 70-dB PSRR at 1 kHz to suppress SMPS ripple from adjacent power stages. Use Value: 150 µVRMS output noise (10 Hz–100 kHz) ensures signal integrity for high-speed transceivers and memory interfaces. |
| Graphics Card GPU Core Supply | SMPS Post-Regulator |
Use Scenario: Delivering dynamically scaled 0.8–1.1 V GPU core voltage in gaming laptops with aggressive thermal envelopes and battery-life targets. IC Role / Device Role / Timing Role: Adjustable LDO used in conjunction with GPU DVFS controller; ADJ pin accepts variable reference to track core voltage demands in real time. Use Value: ±2% accuracy over –40°C to +125°C maintains safe voltage margins during GPU thermal throttling events. | Use Scenario: Tightening output regulation of 3.3 V buck converter feeding industrial PLC I/O modules subject to line/load transients. IC Role / Device Role / Timing Role: Fast-response post-regulator absorbing SMPS ripple and load steps; exploits 240-mV dropout to minimize power loss in cascade configuration. Use Value: 15-µs turn-on delay and sub-µs transient response (<10 µs recovery) maintain <1% output deviation during 2-A load steps. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable LDO applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS75733KTTT | Fixed 3.3-V output; 3-A rating; 250-mV dropout; no VBIAS rail or ADJ pin. | Suitable only for fixed-voltage applications; lacks programmability and dual-rail flexibility. | Select when output voltage is static and board space permits larger TO-263 package. |
| TPS7A8300RGRT | Adjustable 0.8–3.95 V; 3-A; 115-mV dropout; single-input (VIN-only); 7-µVRMS noise. | Lower dropout and noise, but requires higher minimum VIN and lacks VBIAS optimization for ultra-low VIN use cases. | Prefer for ultra-low-noise analog supplies where VIN ≥ VOUT + 115 mV is feasible. |
Compared with TPS75733KTTT and TPS7A8300RGRT, LP38853S-ADJ/NOPB uniquely supports ultra-low VIN operation via dedicated VBIAS rail, making it optimal for systems where input voltage headroom is constrained below 500 mV-especially in post-regulation and battery-sensitive designs.
Availability
LP38853S-ADJ/NOPB is available at Aetrix Electronics and suitable for server core supplies, FPGA I/O rails, graphics card GPU regulation, and SMPS post-regulation requiring stable component supply, long-term lifecycle support, and consistent parametric performance across temperature extremes.
Supply support for LP38853S-ADJ/NOPB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, designing and manufacturing analog ICs, embedded processors, and connectivity solutions for industrial, automotive, and communications markets.
LP38853S-ADJ/NOPB belongs to TI's high-performance LDO portfolio targeting high-current, low-dropout, fast-transient applications-including processor core, FPGA, and ASIC power delivery where precision, thermal efficiency, and reliability are critical.
FAQ
What is the minimum recommended VBIAS voltage for LP38853S-ADJ/NOPB when configuring VOUT = 1.5 V?
The minimum recommended VBIAS voltage for LP38853S-ADJ/NOPB is 4.5 V when VOUT exceeds 1.2 V. Since 1.5 V > 1.2 V, VBIAS must be set between 4.5 V and 5.5 V to ensure proper gate drive and output accuracy. Operating below 4.5 V risks degraded line/load regulation and potential instability per the datasheet's Recommended Operating Conditions table.
Can LP38853S-ADJ/NOPB operate without an external soft-start capacitor?
Yes, LP38853S-ADJ/NOPB can operate without an external soft-start capacitor: the SS pin may be left open if soft-start is not required. However, TI recommends placing a small capacitor (e.g., 100 pF–1 nF) to mitigate noise sensitivity. Leaving SS unconnected eliminates controlled ramp-up, resulting in full inrush current into COUT-acceptable only in systems with robust input staging.
What is the function of the DAP pad on the LP38853S-ADJ/NOPB SO PowerPAD™ package?
On the LP38853S-ADJ/NOPB, the DAP (exposed thermal pad) is electrically connected to GND and serves as the primary thermal interface. It must be soldered to a PCB ground plane with ≥60% solder coverage and multiple thermal vias to achieve the specified RθJA of 48.4°C/W. Failure to properly connect the DAP results in excessive junction temperature and premature thermal shutdown.
How does the ADJ pin reference voltage tolerance affect overall VOUT accuracy in LP38853S-ADJ/NOPB?
The ADJ pin reference voltage in LP38853S-ADJ/NOPB is specified as 500 mV ±1.5% at 25°C and ±2% over –40°C to +125°C. Since VOUT = 0.5 V × (1 + R1/R2), this reference tolerance directly propagates into output error-e.g., a ±2% ADJ error contributes ±2% to total VOUT inaccuracy, independent of resistor tolerance. High-precision resistors alone cannot compensate for ADJ drift.
Is LP38853S-ADJ/NOPB compatible with ceramic output capacitors smaller than 10 µF?
No-LP38853S-ADJ/NOPB is characterized and guaranteed stable only with ≥10-µF ceramic output capacitance (COUT). Using smaller values violates the stability criteria defined in the datasheet's Electrical Characteristics and may cause oscillation or poor transient response. TI explicitly states "Stable with 10-µF Ceramic Capacitors" as a key feature; design deviations require full loop analysis.
LP38853S-ADJ/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Packaging:
- Bulk
- Product Status:
- Active
- Output Configuration:
- Positive
- Output Type:
- Adjustable
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 1.8V
- Voltage Dropout (Max):
- 0.45V @ 3A
- Current - Output:
- 3A
- Current - Quiescent (Iq):
- 300 µA
- Current - Supply (Max):
- 9 mA
- PSRR:
- 80dB ~ 70dB (120Hz ~ 1kHz)
- Control Features:
- Enable, Soft Start
- Protection Features:
- Over Current, Over Temperature, Short Circuit, Under Voltage Lockout (UVLO)
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TO-263 (DDPAK-7)
LP38853S-ADJ/NOPB FAQ
1.How can I place an order for LP38853S-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LP38853S-ADJ/NOPB on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LP38853S-ADJ/NOPB reliable?
The price and inventory of LP38853S-ADJ/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LP38853S-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LP38853S-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LP38853S-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LP38853S-ADJ/NOPB?
LP38853S-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LP38853S-ADJ/NOPB order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LP38853S-ADJ/NOPB?
For technical support, including LP38853S-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LP38853S-ADJ/NOPB requirements.
6.How does Aetrix verify that LP38853S-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LP38853S-ADJ/NOPB products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LP38853S-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LP38853S-ADJ/NOPB?
All LP38853S-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LP38853S-ADJ/NOPB, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LP38853S-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LP38853S-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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