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Texas Instruments LM20343MHX/NOPB
- Part No.:
- LM20343MHX/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 20-PowerTSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM20343MHX/NOPB.pdf
- Description:
- IC REG BUCK ADJ 3A 20HTSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,238
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Product details
Overview
LM20343MHX/NOPB from Texas Instruments is a synchronous buck regulator IC delivering up to 3A continuous output current with 4.5V–36V input range, 0.8V–adjustable output voltage, and externally programmable 250 kHz–1 MHz switching frequency. It integrates 130 mΩ high-side and 110 mΩ low-side MOSFETs and features precision 0.8 V ±1.5% feedback reference for stable point-of-load regulation in FPGA and DSP power rails.
For engineers reviewing the LM20343MHX/NOPB datasheet, LM20343MHX/NOPB pinout, LM20343MHX/NOPB application, or LM20343MHX/NOPB equivalent, key selection considerations include its current-mode control with nonlinear slope compensation, pre-biased startup capability, PGOOD monitoring, and thermal/overvoltage/overcurrent protection-critical for industrial and communications power systems requiring robust transient response and rail sequencing.
Technical Context
The LM20343MHX/NOPB implements peak current mode control with parabolic slope compensation that adapts to output voltage level-ensuring stability across 0.8V–12V outputs without external tuning. Its error amplifier provides 515 µmho transconductance and 7 MHz gain-bandwidth product, enabling stable loop compensation with only two external components (RC1, CC1).
Internal protection includes cycle-by-cycle current limiting (4.3–6.0 A), thermal shutdown at 170°C with 20°C hysteresis, and overvoltage protection triggered at 107–112% of VFB. The SS/TRK pin supports both soft-start timing (via external capacitor) and voltage tracking of higher rails, while the EN pin offers 1.25 V threshold with 50 mV hysteresis for precise UVLO configuration.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5 V to 36 V - supports wide industrial bus voltages including 12 V, 24 V, and 32 V systems without external step-down. |
| Output Current | 3 A continuous - sufficient for powering mid-range FPGAs, DSPs, and ASICs with margin for transient loads. |
| Feedback Reference | 0.8 V ±1.5% - enables accurate output regulation down to 0.8 V and simplifies resistor-divider design for common logic supply rails. |
| Switching Frequency | 250 kHz to 1 MHz - adjustable via RT-to-AGND resistor; allows optimization of efficiency vs. size (e.g., 750 kHz for 4.7 µH inductor). |
| Integrated MOSFETs | 130 mΩ HS / 110 mΩ LS - reduces conduction loss and eliminates need for external power switches, lowering BOM count and layout complexity. |
| Efficiency | 94% peak - achieved with synchronous rectification and low RDS(on), minimizing thermal load in compact PCB layouts. |
| Soft-Start | Programmable via SS/TRK capacitor - prevents inrush current and ensures monotonic startup, critical for multi-rail sequencing with PGOOD. |
| Protection Features | OVP, UVP, OCP, thermal shutdown - autonomous fault handling without external supervision, enhancing system reliability. |
Pinout & Package
LM20343MHX/NOPB is housed in a thermally enhanced 20-pin HTSSOP package with exposed pad (PWP0020A), designed for direct soldering to PCB ground plane to achieve θJA = 27°C/W (4-layer board) and θJC = 5.6°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 SS/TRK | Soft-start/Tracking control | 4.5 µA internal current source charges external capacitor; enables monotonic startup or rail tracking with low-impedance source. |
| 2 FB | Feedback input | Connects to resistor divider; referenced to internal 0.8 V bandgap-sets output voltage with ±1.5% accuracy. |
| 3 PGOOD | Power-good open-drain output | Asserts high when VOUT is within 93–97% of target; requires 10–100 kΩ pull-up for system sequencing. |
| 4 COMP | Error amplifier output | Interface for Type II/III compensation network (RC1, CC1); determines loop stability and transient response. |
| 5,6,15,16 VIN | Main input supply | Accepts 4.5–36 V; multiple pins reduce trace resistance and improve current sharing in high-current paths. |
| 7,8,13,14 SW | Switch node | Drain of HS FET / source of LS FET; connects to inductor and bootstrap capacitor-requires tight layout to minimize ringing. |
| 9,10,11 GND | Power ground | Common return for power MOSFETs; must be tied to exposed pad and PCB ground plane for thermal and EMI performance. |
| 12 AGND | Analog ground | Reference for error amp, comparators, and bias circuits-should be star-connected to GND near COMP/FB pins. |
| 17 BOOT | Bootstrap supply | Charged via internal diode from VCC; supplies gate drive for HS FET-requires 0.1 µF ceramic cap between BOOT and SW. |
| 18 VCC | Internal LDO output | Regulated ~5.5 V output (up to 7.2 V input); powers internal circuitry and BOOT driver-requires 0.1–1 µF decoupling. |
| 19 EN | Enable/UVLO input | 1.25 V threshold with 50 mV hysteresis; internal 2 µA pull-up enables default-on operation if left floating. |
| 20 RT | Oscillator frequency adjust | 550 mV bias point; resistor to AGND sets fSW from 250 kHz to 1 MHz per TI's RRT = (78,000/fSW) − 55 formula. |
| EP Exposed Pad | Thermal & electrical ground | Weakly connected to GND internally; must be soldered to large PCB copper area for thermal dissipation and noise reduction. |
Key Features
| Feature | Design Value |
|---|---|
| Nonlinear slope compensation | Parabolic ramp adapts to output voltage-eliminates need for manual slope tuning and ensures stability across full VOUT range (0.8 V–12 V). |
| Pre-biased startup support | Does not sink current during startup if VOUT > 0 V-prevents damage to downstream loads (e.g., FPGAs) powered via parasitic paths. |
| Adjustable soft-start & tracking | Single SS/TRK pin configures either timed ramp (capacitor) or external rail tracking-enables flexible power sequencing in multi-supply systems. |
| Integrated protection suite | OVP (107–112% VFB), thermal shutdown (170°C), and cycle-by-cycle current limit (4.3–6.0 A)-reduces external fault management components. |
| High-accuracy enable input | 1.25 V ±25 mV EN threshold with hysteresis-allows precise line UVLO setting using resistor divider from VIN, independent of internal UVLO. |
| Exposed-pad HTSSOP package | 20-pin thermally optimized package-delivers θJC = 5.6°C/W without heatsink, supporting 3 A continuous operation in space-constrained designs. |
Applications
| Industrial PLC I/O Modules | FPGA Core Voltage Supply |
|---|---|
Use Scenario: Powering isolated digital I/O channels in programmable logic controllers operating from 24 V DC industrial bus. IC Role / Device Role / Timing Role: Primary buck regulator providing clean, sequenced 3.3 V or 5 V rail with PGOOD signaling for controller boot validation. Use Value: 4.5–36 V input range accepts wide bus tolerances; pre-bias startup avoids latch-up during hot-swap I/O card insertion. | Use Scenario: Delivering tightly regulated 1.2 V core voltage to Xilinx Artix-7 or Intel Cyclone V FPGA under dynamic load conditions. IC Role / Device Role / Timing Role: Synchronous buck converter with fast transient response and soft-start tracking for safe core voltage ramp-up alongside auxiliary rails. Use Value: 3 A continuous current and 94% peak efficiency minimize thermal stress; SS/TRK pin enables voltage tracking with 2.5 V I/O rail. |
| Automotive Infotainment Head Units | Telecom Base Station Line Cards |
Use Scenario: Generating 1.8 V and 3.3 V rails for ARM-based application processors and audio codecs in 12 V vehicle systems. IC Role / Device Role / Timing Role: High-voltage input buck regulator with UVLO hysteresis and thermal protection for unregulated automotive battery environments. Use Value: 4.25 V UVLO rising threshold and 350 mV hysteresis prevent restart oscillation during cranking; integrated OVP guards against load dump transients. | Use Scenario: Point-of-load conversion for DSPs and SerDes interfaces on 48 V telecom line cards requiring strict ripple and sequencing. IC Role / Device Role / Timing Role: Adjustable-frequency buck regulator delivering 1.0 V or 1.5 V with PGOOD and EN-controlled sequencing across multiple voltage domains. Use Value: 250–1000 kHz frequency adjustment enables EMI spread-spectrum tuning; precision 0.8 V reference ensures <±1% output tolerance at full load. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM20343MH/NOPB | Tape-and-reel packaging variant; identical electrical specs, pinout, and thermal performance. | No functional difference-used for automated SMT assembly where tape format is required. | Select LM20343MH/NOPB for high-volume pick-and-place; LM20343MHX/NOPB is cut-tape/reel for prototyping or low-volume production. |
| TPS54340DDAR | 3.5 A output, 4.5–42 V input, 2.5% VREF accuracy, no PGOOD or tracking pin; uses different compensation topology. | Lacks SS/TRK and PGOOD-requires external monitoring circuitry for sequencing and fault reporting. | Choose TPS54340DDAR only if higher input voltage (up to 42 V) is needed and PGOOD/track functionality is not required. |
Compared with LM20343MH/NOPB, the LM20343MHX/NOPB offers identical performance in cut-tape form for flexibility in small-batch builds, while TPS54340DDAR trades away critical sequencing features for wider input range-making LM20343MHX/NOPB preferable for FPGA/DSP applications demanding rail coordination and fault visibility.
Availability
LM20343MHX/NOPB is available at Aetrix Electronics and suitable for industrial PLCs, FPGA power supplies, automotive infotainment systems, and telecom line cards requiring stable component supply, long-term lifecycle support, and consistent parametric performance across temperature and load.
Supply support for LM20343MHX/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 expertise in high-reliability power conversion ICs.
The LM20343MHX/NOPB belongs to TI's high-voltage synchronous buck regulator product line, engineered for robust point-of-load regulation in harsh environments-including industrial automation, automotive, and communications infrastructure-where wide input range, integrated protection, and sequencing capability are essential.
FAQ
What is the minimum recommended output voltage for LM20343MHX/NOPB?
The LM20343MHX/NOPB supports adjustable output voltages down to 0.8 V, set by the feedback resistor divider connected to the FB pin. This 0.8 V reference voltage has ±1.5% accuracy across temperature and load, enabling precise regulation for modern low-voltage logic cores such as FPGA I/O banks and ARM processor cores. Operation below 0.8 V is not supported.
How does the SS/TRK pin function in LM20343MHX/NOPB during startup?
In LM20343MHX/NOPB, the SS/TRK pin serves dual roles: when used as soft-start, an internal 4.5 µA current source charges an external capacitor to generate a controlled voltage ramp, preventing inrush current; when used as track input, it follows an external voltage ramp (e.g., from a higher rail) with low-impedance sourcing, enabling coordinated power-up of multiple regulators. If left unconnected, LM20343MHX/NOPB defaults to a 1 ms internal soft-start.
Can LM20343MHX/NOPB operate with a pre-biased output voltage?
Yes, LM20343MHX/NOPB supports pre-biased startup: when the output voltage is non-zero at power-on (e.g., due to back-powering from other rails), the device will not sink current through the low-side FET until the soft-start ramp exceeds the FB pin voltage. This behavior protects sensitive loads like FPGAs and ASICs from reverse current damage during hot-swap or multi-rail sequencing events.
What is the purpose of the RT pin in LM20343MHX/NOPB, and how is it configured?
The RT pin in LM20343MHX/NOPB adjusts the internal oscillator frequency from 250 kHz to 1 MHz by connecting an external resistor (RRT) between RT and AGND. The pin maintains a nominal 550 mV bias voltage, and RRT value is calculated using TI's formula RRT = (78,000 / fSW) − 55 (with fSW in kHz and RRT in kΩ). Omitting RRT disables operation.
Does LM20343MHX/NOPB require external MOSFETs for operation?
No, LM20343MHX/NOPB integrates both high-side (130 mΩ) and low-side (110 mΩ) power MOSFETs, eliminating the need for external switches. This integration reduces component count, simplifies PCB layout, and improves efficiency-especially at medium loads (1–3 A)-while maintaining full control over switching frequency, compensation, and protection functions via its dedicated pins.
LM20343MHX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 20-PowerTSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 28.8V
- Current - Output:
- 3A
- Frequency - Switching:
- 250kHz ~ 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-HTSSOP
LM20343MHX/NOPB FAQ
1.How can I place an order for LM20343MHX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM20343MHX/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 LM20343MHX/NOPB reliable?
The price and inventory of LM20343MHX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM20343MHX/NOPB is usually 5 days.
3.What payment methods are accepted for LM20343MHX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM20343MHX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM20343MHX/NOPB?
LM20343MHX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM20343MHX/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 LM20343MHX/NOPB?
For technical support, including LM20343MHX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM20343MHX/NOPB requirements.
6.How does Aetrix verify that LM20343MHX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM20343MHX/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 LM20343MHX/NOPB meets industry standards.
7.What is the process for return or replacement of LM20343MHX/NOPB?
All LM20343MHX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM20343MHX/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 LM20343MHX/NOPB part is unused and in its original packaging.
Return procedure for LM20343MHX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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