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Texas Instruments LM20343MH/NOPB
- Part No.:
- LM20343MH/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 20-PowerTSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM20343MH/NOPB.pdf
- Description:
- IC REG BUCK ADJ 3A 20HTSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:192
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Product details
Overview
LM20343MH/NOPB from Texas Instruments is a 36V, 3A synchronous buck regulator with current-mode control, integrated 130 mΩ/110 mΩ MOSFETs, and adjustable 250 kHz–1 MHz switching frequency. It delivers regulated DC output down to 0.8V with 1.5% feedback accuracy and supports pre-biased startup for FPGA/DSP power sequencing in industrial and communications systems.
For engineers reviewing the LM20343MH/NOPB datasheet, LM20343MH/NOPB pinout, LM20343MH/NOPB application, or LM20343MH/NOPB equivalent, key selection considerations include its 4.5V–36V input range, PGOOD monitoring, precision enable with hysteresis, soft-start/tracking capability, and thermal shutdown at 170°C.
Technical Context
The LM20343MH/NOPB implements peak current-mode control with non-linear parabolic slope compensation-dynamically adjusted per output voltage-to ensure stability across duty cycles up to 80% and eliminate sub-harmonic oscillation without external ramp injection. Its error amplifier provides 515 µmho transconductance and 7 MHz gain-bandwidth for robust loop compensation using only two external components (RC1, CC1).
Internal protection includes cycle-by-cycle current limiting (4.3–6.0 A), overvoltage protection (107–112% of VFB), UVLO with 450 mV hysteresis, and thermal shutdown with 20°C hysteresis. The device operates with ±10 mV SS/TRK tracking accuracy and maintains PGOOD assertion within 20 µs deglitch timing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 36V - supports wide-input industrial and automotive bus rails without external pre-regulation. |
| Output Current | 3A continuous - sufficient for powering mid-tier FPGAs, DSPs, and ASIC cores with margin for transient loads. |
| Switching Frequency | 250 kHz to 1.0 MHz - adjustable via RT-to-AGND resistor; enables optimization of size (higher fSW) vs. efficiency (lower fSW). |
| Feedback Accuracy | ±1.5% at 0.8V reference - ensures tight output regulation across temperature and line/load variations. |
| Integrated MOSFETs | 130 mΩ high-side / 110 mΩ low-side - reduces conduction losses and eliminates need for external power switches. |
| Thermal Shutdown | 170°C with 20°C hysteresis - protects against sustained overload or poor PCB thermal design while enabling automatic recovery. |
| Soft-Start Time | Programmable via external capacitor on SS/TRK - prevents inrush current; default internal ramp is 1 ms if unconnected. |
| Power Good Delay | 20 µs - provides noise-immune output voltage monitoring with built-in deglitching for reliable system sequencing. |
Pinout & Package
LM20343MH/NOPB is housed in a thermally enhanced 20-pin HTSSOP package with exposed pad (PWP0020A), requiring solder connection of the EP pad to PCB ground plane for optimal thermal performance (θJC = 5.6°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 SS/TRK | Soft-start or 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 precise 0.8V internal bandgap; bias current ≤50 nA minimizes divider error. |
| 3 PGOOD | Open-drain power-good indicator | Asserts low when VOUT falls outside 93–97% of VFB; requires 10–100 kΩ pull-up for logic-level interfacing. |
| 4 COMP | Error amplifier output / PWM input | Interface point for Type II/III compensation network; sink/source capability supports stable loop design with ceramic or polymer capacitors. |
| 5,6,15,16 VIN | Main input supply | High-current path for 4.5–36V input; multiple pins reduce trace resistance and improve thermal distribution. |
| 7,8,13,14 SW | Switch node | Drain of low-side NMOS and source of high-side NMOS; connects to external inductor and bootstrap capacitor. |
| 9,10,11 GND | Power ground | Common return for high-current MOSFET paths; separate from AGND to minimize noise coupling into control circuitry. |
| 12 AGND | Analog ground | Reference for error amplifier, oscillator, and comparators; must be routed separately from power ground and tied at single point. |
| 17 BOOT | Bootstrap capacitor connection | Charged via internal diode from VCC; supplies gate drive for high-side MOSFET; requires 10–100 nF ceramic capacitor to SW. |
| 18 VCC | Internal LDO output | Regulated ~5.5V output (up to 7.2V VIN); powers gate drivers and internal circuitry; requires 0.1–1 µF decoupling. |
| 19 EN | Enable with UVLO | 1.25V typical enable threshold with 50 mV hysteresis; internal 2 µA pull-up enables default-on operation if left floating. |
| 20 RT | Oscillator frequency set | 550 mV bias point; external resistor to AGND sets fSW from 250 kHz to 1 MHz per published curve. |
| EP | Exposed pad | Internally weakly connected to GND; must be soldered to PCB ground plane to achieve rated θJA = 27°C/W. |
Key Features
| Feature | Design Value |
|---|---|
| Non-linear slope compensation | Parabolic ramp dynamically scaled to output voltage - ensures stable current-mode operation at all duty cycles without external components. |
| Pre-biased startup support | No negative current injection during startup - prevents damage to downstream loads (e.g., FPGAs) with parasitic conduction paths. |
| Adjustable soft-start & tracking | Single SS/TRK pin supports both functions - simplifies multi-rail sequencing and eliminates need for external tracking ICs. |
| Integrated OVP/UVP/OTP protection | Independent comparators with hysteresis - enables autonomous fault response without host controller intervention. |
| Resistor-programmed frequency | RT pin interface with predictable fSW vs. RRT relationship - allows precise EMI tuning and layout-driven frequency selection. |
| Exposed-pad HTSSOP package | 20-pin thermally optimized footprint - achieves 5.6°C/W junction-to-case resistance without heatsinks or airflow. |
Applications
| Industrial PLC Power Supply | FPGA Core Voltage Regulation |
|---|---|
Use Scenario: Regulating 12V or 24V backplane to 1.2V/1.5V for programmable logic controllers with strict thermal and reliability requirements. IC Role / Device Role / Timing Role: Primary synchronous buck converter delivering 3A continuous current with PGOOD signaling for system health monitoring. Use Value: Integrated MOSFETs and exposed-pad HTSSOP eliminate discrete switch losses and simplify thermal management in confined enclosures. | Use Scenario: Powering Xilinx or Intel FPGA core rails where output voltage must track auxiliary supplies during power-up. IC Role / Device Role / Timing Role: Adjustable-frequency buck regulator with SS/TRK pin used for monotonic, pre-biased startup and rail tracking. Use Value: Non-linear slope compensation ensures stability across full VOUT range (0.8V–5V), while 1.5% VFB accuracy maintains tight core voltage tolerance. |
| Automotive Infotainment DC-DC | Communications Base Station Bias |
Use Scenario: Converting 12V vehicle battery to 3.3V/5V for infotainment SoCs operating in harsh thermal environments (-40°C to +125°C). IC Role / Device Role / Timing Role: High-input-voltage buck regulator with UVLO hysteresis and thermal shutdown for robust operation under load dump and cold-crank conditions. Use Value: 4.5V–36V input range accommodates wide automotive transients; 170°C thermal shutdown prevents latch-up during sustained overload. | Use Scenario: Generating stable 3.3V/5V bias for RF front-end modules and baseband processors in 4G/5G macrocells. IC Role / Device Role / Timing Role: High-efficiency (94% peak) synchronous buck supplying clean, low-noise power with PGOOD for hot-swap sequencing. Use Value: 20 µs PGOOD deglitching prevents false fault assertions during RF burst transients; 130/110 mΩ MOSFETs minimize conduction loss at high ambient temperatures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM20343TME/NOPB | Same die, 20-pin WQFN package (no exposed pad); θJA = 36°C/W vs. 27°C/W for HTSSOP. | Limited thermal headroom in high-power-density layouts; requires more aggressive PCB copper pour or airflow. | Select LM20343TME/NOPB only when space-constrained layouts prohibit HTSSOP or when WQFN reflow compatibility is required. |
| TPS54340DDAR | 3.5A rating, 4.5–42V input, fixed 500 kHz fSW; no SS/TRK pin; uses external compensation but lacks pre-bias startup. | Suitable for simpler, fixed-frequency designs without rail tracking or pre-biased loads; lower peak efficiency (93%) at 3A. | Choose TPS54340DDAR for cost-sensitive, non-tracking applications where 3.5A headroom and extended 42V input are prioritized over soft-start flexibility. |
Compared with LM20343TME/NOPB, LM20343MH/NOPB offers superior thermal performance via exposed-pad HTSSOP, critical for sustained 3A operation in sealed enclosures; versus TPS54340DDAR, it provides essential SS/TRK functionality and pre-bias safety for complex multi-rail systems, albeit with slightly higher BOM count due to RT/RC1/CC1 components.
Availability
LM20343MH/NOPB is available at Aetrix Electronics and suitable for industrial PLC power supplies, FPGA core regulation, automotive infotainment systems, and communications base station bias requiring stable component supply and long-term manufacturability.
Supply support for LM20343MH/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 ICs, with decades of expertise in high-reliability power conversion solutions.
The LM20343MH/NOPB belongs to TI's high-voltage synchronous buck regulator product line, engineered for robust, easy-to-design DC-DC conversion in industrial, automotive, and communications infrastructure where input voltage range, thermal resilience, and protection integrity are critical.
FAQ
What is the minimum recommended output voltage for LM20343MH/NOPB?
The LM20343MH/NOPB supports adjustable output voltages down to 0.8V, set by the feedback resistor divider (RFB1/RFB2) referenced to its internal 0.8V bandgap. This 0.8V minimum enables direct regulation for modern low-voltage FPGA and ASIC cores. Operation below 0.8V is not supported, as the feedback comparator is designed around this precise reference.
Does LM20343MH/NOPB support pre-biased output startup?
Yes, LM20343MH/NOPB fully supports pre-biased startup: during power-up, it will not sink current from a pre-charged output until the internal soft-start ramp exceeds the FB pin voltage. This prevents reverse current flow through load parasitics-critical for safely powering FPGAs and DSPs in multi-rail systems without external diodes or sequencing controllers.
How is the switching frequency programmed on LM20343MH/NOPB?
The switching frequency of LM20343MH/NOPB is set by an external resistor (RRT) connected between the RT pin and AGND. With RRT = 49.9 kΩ, fSW ≈ 750 kHz; with RRT = 249 kΩ, fSW ≈ 250 kHz. The RT pin maintains a 550 mV bias, and the fSW vs. RRT relationship is characterized in the datasheet's Typical Performance Characteristics (Figure 16). Omitting RRT disables operation.
What thermal performance can be expected from LM20343MH/NOPB in a standard PCB layout?
In a 4-layer 2" × 2" PCB with 1 oz. inner/2 oz. outer copper, LM20343MH/NOPB achieves θJA = 27°C/W and θJC = 5.6°C/W. With the exposed pad properly soldered to the ground plane, junction temperature rise is ~81°C at 3A/12V input/3.3V output (94% efficiency). Thermal shutdown activates at 170°C, providing robust protection under sustained overload or poor airflow conditions.
Can LM20343MH/NOPB be used in applications requiring output voltage tracking?
Yes, LM20343MH/NOPB supports voltage tracking via its SS/TRK pin: when driven by a low-impedance external ramp (e.g., from another regulator's soft-start pin), the output follows that ramp monotonically. Tracking accuracy is ±10 mV at 0.4V on SS/TRK, enabling precise sequencing of multiple rails-such as coordinating core and I/O voltages in FPGA power trees-without additional tracking ICs.
LM20343MH/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 20-PowerTSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- 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
LM20343MH/NOPB FAQ
1.How can I place an order for LM20343MH/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM20343MH/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 LM20343MH/NOPB reliable?
The price and inventory of LM20343MH/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM20343MH/NOPB is usually 5 days.
3.What payment methods are accepted for LM20343MH/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM20343MH/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM20343MH/NOPB?
LM20343MH/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM20343MH/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 LM20343MH/NOPB?
For technical support, including LM20343MH/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM20343MH/NOPB requirements.
6.How does Aetrix verify that LM20343MH/NOPB is sourced from the original manufacturer or authorized distributors?
All LM20343MH/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 LM20343MH/NOPB meets industry standards.
7.What is the process for return or replacement of LM20343MH/NOPB?
All LM20343MH/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM20343MH/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 LM20343MH/NOPB part is unused and in its original packaging.
Return procedure for LM20343MH/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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