My Inquiry
My Account
Texas Instruments LP38855SX-1.2/NOPB
- Part No.:
- LP38855SX-1.2/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LP38855SX-1.2/NOPB.pdf
- Description:
- IC REG LINEAR 1.2V 1.5A DDPAK
- Quantity:
- Payment:
- Shipping:
Inventory:779
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LP38855SX-1.2/NOPB from Texas Instruments is a 1.5A fast-response, high-accuracy LDO linear regulator with dual-rail operation (VIN and VBIAS), delivering a fixed 1.2V output with ±1.0% tolerance at 25°C, 130 mV typical dropout at full load, and stable operation with 10 µF ceramic output capacitance. It serves as a core voltage regulator for DSPs, FPGAs, and SMPS post-regulation in server and graphics applications.
For engineers reviewing the LP38855SX-1.2/NOPB datasheet, LP38855SX-1.2/NOPB pinout, LP38855SX-1.2/NOPB application, or LP38855SX-1.2/NOPB equivalent, key selection criteria include its dual-supply architecture (VIN/VBIAS), ultra-low ground current (12 mA at 1.5A), enable-controlled sequencing, thermal shutdown (160°C), and DDPAK/TO-263 package compatibility with PCB copper plane heat-sinking.
Technical Context
The LP38855SX-1.2/NOPB employs an N-MOS pass transistor driven by a separate VBIAS rail (3.0–5.5V), enabling ultra-low VIN operation down to VOUT + VDO while isolating bias circuitry from high-current paths. Its CMOS control architecture delivers low quiescent current and wide bandwidth without requiring large external compensation.
It integrates under-voltage lockout (UVLO) on VBIAS (2.45V threshold, 150 mV hysteresis), enable input with 1.25V turn-on threshold (100 mV hysteresis), and thermal shutdown (160°C, 10°C hysteresis). Output stability is guaranteed with ≥10 µF X5R/X7R ceramic COUT and ≥1 µF CBIAS.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.2V ±1.0% at TJ = 25°C; ±2.0% over 0°C to +125°C - ensures tight core voltage compliance for digital ICs. |
| Max Output Current | 1.5A continuous - supports high-current FPGA I/O banks and ASIC cores without derating at moderate ambient. |
| Dropout Voltage | 130 mV typical at 1.5A - enables regulation from 1.33V input, critical for low-voltage post-regulation after buck converters. |
| VBIAS Range | 3.0V to 5.5V - decouples control logic power from noisy high-current VIN, improving PSRR and noise immunity. |
| Ground Current | 12 mA typical from VIN at 1.5A load - minimizes system-level power loss in high-efficiency power trees. |
| PSRR @ 1 kHz | 65 dB for VIN ripple, 58 dB for VBIAS ripple - suppresses switching noise from upstream SMPS and bias rails. |
| Thermal Shutdown | 160°C junction temperature with 10°C hysteresis - provides robust fault protection during overload or inadequate heatsinking. |
Pinout & Package
LP38855SX-1.2/NOPB uses the DDPAK/TO-263 (Package Number KTT0005B) 5-lead surface-mount package with exposed thermal tab soldered to PCB copper for enhanced thermal performance (θJA = 32°C/W minimum with 1-in² copper).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN | Enable control input | Active-high logic input (1.25V threshold); internal 180 kΩ pull-up to VBIAS - enables precise power sequencing without external components. |
| IN | Main power input | High-current VIN rail (up to 1.5A); must be ≥ VOUT + VDO and ≤ VBIAS - carries load current and dissipates primary power loss. |
| GND | Analog ground reference | Common return for feedback and control circuits; requires low-impedance connection to minimize noise coupling. |
| OUT | Regulated output | Delivers stable 1.2V to load; must connect ≥10 µF ceramic capacitor within 1 cm and directly to GND pin. |
| BIAS | Bias supply input | Low-current VBIAS rail (3.0–5.5V); powers internal reference, error amplifier, and N-MOS gate drive - isolates control integrity from VIN noise. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-rail architecture (VIN + VBIAS) | Enables ultra-low VIN operation while maintaining high PSRR and low noise via independent bias path. |
| Stable with 10 µF ceramic COUT | Eliminates need for tantalum or electrolytic capacitors, reducing board area, cost, and aging-related failure modes. |
| Fast transient response | Supports dynamic load steps in DSP/FPGA cores without excessive output droop or overshoot (see Fig. 18–20). |
| Low shutdown current | 1 µA typical IIN(GND) when EN = low - preserves battery or standby power in always-on systems. |
| Integrated UVLO and thermal protection | Prevents malfunction during brownout or thermal overload without external monitoring circuitry. |
Applications
| ASIC Power Supplies in Servers | DSP Core Voltage Regulation |
|---|---|
Use Scenario: Powering multi-core ASICs in rack-mounted servers where tight voltage tolerance and low noise are required for signal integrity. IC Role / Device Role / Timing Role: Primary core LDO delivering 1.2V to ASIC logic blocks with ±1.0% accuracy across temperature and load. Use Value: Maintains timing margins under dynamic load transients via fast response and 65 dB PSRR at 1 kHz, reducing bit errors. | Use Scenario: Regulating voltage for real-time DSP processors in telecom baseband units with strict EMI and thermal constraints. IC Role / Device Role / Timing Role: Low-noise post-regulator following a buck converter, supplying clean 1.2V to DSP I/O and memory interfaces. Use Value: 150 µVRMS integrated output noise (10 Hz–100 kHz) prevents clock jitter and ADC quantization errors. |
| FPGA I/O Bank Supply | SMPS Post-Regulator |
Use Scenario: Providing configurable 1.2V I/O supply to Xilinx/Intel FPGA banks in industrial control modules operating from -40°C to +125°C. IC Role / Device Role / Timing Role: High-accuracy, thermally robust LDO ensuring consistent I/O voltage margin across extended temperature range. Use Value: ±2.0% output tolerance over -40°C to +125°C guarantees setup/hold timing compliance in worst-case thermal conditions. | Use Scenario: Tightening output voltage accuracy and reducing ripple/noise of a 12V-to-1.2V two-stage power architecture in graphics cards. IC Role / Device Role / Timing Role: Final-stage LDO suppressing residual switching noise from upstream DC/DC converter. Use Value: 58 dB PSRR on VBIAS rail rejects noise coupled through shared bias supplies, improving overall system SNR. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LDO regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPL7407LADGQR | 7-channel 500mA NMOS array with 1.2V fixed output; no VBIAS rail; higher dropout (250 mV @ 500mA) | Targeted at GPIO/peripheral driving, not high-current core regulation | Use only for distributed low-power loads; insufficient for 1.5A FPGA core rails. |
| TPS7A8300RGRT | 2A LDO with 1.2V option, 75 mV dropout, single-rail (VIN only), 6.5 µVRMS noise | Higher current and lower noise, but lacks VBIAS isolation and requires higher minimum VIN | Preferred when VIN ≥ 1.275V and board space allows larger 20-pin QFN; not suitable for ultra-low-VIN scenarios. |
Compared with TPL7407LADGQR and TPS7A8300RGRT, LP38855SX-1.2/NOPB uniquely balances 1.5A capability, ultra-low dropout, and dual-rail architecture-enabling reliable regulation from marginal input voltages where single-rail LDOs fail, while offering better thermal management than multi-channel alternatives.
Availability
LP38855SX-1.2/NOPB is available at Aetrix Electronics and suitable for server core supplies, FPGA I/O banks, and SMPS post-regulation requiring stable component supply, long-term production continuity, and RoHS-exempt lead-finish compliance for high-reliability thermal cycling.
Supply support for LP38855SX-1.2/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 leader specializing in analog, embedded processing, and power management technologies, with decades of LDO design heritage and automotive-grade reliability validation.
The LP38855 product line was engineered for high-current, low-noise point-of-load regulation in computing and communications infrastructure-specifically addressing thermal, accuracy, and transient challenges in multi-rail digital systems.
FAQ
What is the minimum input voltage required for LP38855SX-1.2/NOPB to regulate 1.2V output?
The minimum VIN is VOUT + VDO = 1.2V + 0.13V = 1.33V (typical at 1.5A). However, VIN must also be ≤ VBIAS and ≥ (VOUT + VDO) across all load/temperature conditions. The datasheet specifies VIN operating range as (VOUT + VDO) to VBIAS, so actual minimum depends on VBIAS selection and worst-case VDO (180 mV max per Electrical Characteristics table).
Can LP38855SX-1.2/NOPB operate with VBIAS = 2.8V?
No. LP38855SX-1.2/NOPB requires VBIAS between 3.0V and 5.5V per Operating Ratings. At 2.8V, the device enters UVLO (threshold ≈2.45V, hysteresis 150 mV), disabling regulation. Operation below 3.0V is undefined and may result in unstable output or uncontrolled shutdown.
Is an external pull-down resistor required on the EN pin of LP38855SX-1.2/NOPB?
No. LP38855SX-1.2/NOPB features an internal 180 kΩ pull-up resistor to VBIAS on the EN pin. If enable functionality is unused, connect EN directly to VBIAS. A pull-down is only needed if active low control is required; in that case, ensure the driving source can sink sufficient current to overcome the internal pull-up and pull EN below 1.15V (VEN(ON) – hysteresis).
What is the maximum allowable copper area for thermal performance of LP38855SX-1.2/NOPB in DDPAK/TO-263 package?
Per Figure 27 in the datasheet, increasing copper area beyond 1 square inch yields diminishing returns for θJA reduction. The minimum achievable θJA is 32°C/W with ≥1 in² of 1-oz copper (no solder mask). Larger areas do not significantly improve thermal resistance, making 1 in² the practical design optimum for cost and layout efficiency.
Does LP38855SX-1.2/NOPB require a specific ESR range for the output capacitor?
No. Unlike many older LDOs, LP38855SX-1.2/NOPB is explicitly designed to be stable with low-ESR ceramic capacitors (X5R/X7R, ≥10 µF) and does not require ESR-based zero compensation. The datasheet warns against Z5U/Y5F ceramics due to capacitance drift, but imposes no ESR minimum or maximum - enabling use of modern low-ESR MLCCs without risk of oscillation.
LP38855SX-1.2/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 1.2V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 0.18V @ 1.5A
- Current - Output:
- 1.5A
- Current - Quiescent (Iq):
- 300 µA
- Current - Supply (Max):
- 15 mA
- PSRR:
- 80dB ~ 65dB (120Hz ~ 1kHz)
- Control Features:
- Enable
- 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-5)
LP38855SX-1.2/NOPB FAQ
1.How can I place an order for LP38855SX-1.2/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LP38855SX-1.2/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 LP38855SX-1.2/NOPB reliable?
The price and inventory of LP38855SX-1.2/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LP38855SX-1.2/NOPB is usually 5 days.
3.What payment methods are accepted for LP38855SX-1.2/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LP38855SX-1.2/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LP38855SX-1.2/NOPB?
LP38855SX-1.2/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LP38855SX-1.2/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 LP38855SX-1.2/NOPB?
For technical support, including LP38855SX-1.2/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LP38855SX-1.2/NOPB requirements.
6.How does Aetrix verify that LP38855SX-1.2/NOPB is sourced from the original manufacturer or authorized distributors?
All LP38855SX-1.2/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 LP38855SX-1.2/NOPB meets industry standards.
7.What is the process for return or replacement of LP38855SX-1.2/NOPB?
All LP38855SX-1.2/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LP38855SX-1.2/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 LP38855SX-1.2/NOPB part is unused and in its original packaging.
Return procedure for LP38855SX-1.2/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LP38855SX-1.2/NOPB Tags
-
MIC5504-1.8YM5-TR
Microchip Technology
-
MIC5504-3.3YM5-TR
Microchip Technology
-
MIC5365-3.0YC5-TR
Microchip Technology
-
MIC5365-1.8YC5-TR
Microchip Technology
-
MIC5365-2.5YC5-TR
Microchip Technology
-
MIC5365-3.3YC5-TR
Microchip Technology
-
MIC5365-3.3YD5-TR
Microchip Technology
-
MIC5317-3.3YM5-TR
Microchip Technology
-
TLV1117LV33DCYR
Texas Instruments
-
MIC5317-3.3YMT-TZ
Microchip Technology
-
MIC5528-3.3YMT-TR
Microchip Technology
-
TLV75801PDRVR
Texas Instruments
Tech Hub
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
LDO regulator guide covering low dropout voltage, power dissipation, thermal design, PSRR, output noise, capacitor stability, adjustable LDO circuits, LDO vs buck converter and datasheet selection chec…
Conditional Access Module guide covering CAM meaning, CI/CI+ interface, smart card authorization, DVB security workflow, TV and set-top box compatibility, internal electronics, ESD protection, connecto…
Guide to electronic component obsolescence covering EOL risk, PCN/PDN notices, last-time buy planning, replacement options, form-fit-function validation, counterfeit risk and BOM lifecycle management.
18650 battery guide covering lithium-ion cell basics, 3.6V/3.7V voltage, 4.2V charging, mAh and Wh capacity, protected cells, chargers, BMS, series-parallel packs, holders, welding and sourcing checks.…
