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Texas Instruments LMR33640ADDAR
- Part No.:
- LMR33640ADDAR
- Manufacturer:
- Texas Instruments
- Package:
- 8-PowerSOIC (0.154", 3.90mm Width)
- Datasheet:
-
LMR33640ADDAR.pdf
- Description:
- IC REG BUCK ADJ 4A 8SOPWR
- Quantity:
- Payment:
- Shipping:
Inventory:2,715
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Product details
Overview
LMR33640ADDAR from Texas Instruments is a synchronous step-down DC/DC converter delivering up to 4 A output current with input voltage range 3.8 V to 36 V, output voltage adjustable from 1 V to 24 V, peak efficiency >95%, and operating junction temperature from –40°C to +125°C - used in industrial motor drives and PLC power rails.
For engineers reviewing the LMR33640ADDAR datasheet, LMR33640ADDAR pinout, LMR33640ADDAR application, or LMR33640ADDAR equivalent, key selection criteria include its 400-kHz fixed switching frequency, integrated compensation, precision enable threshold (1.231 V typ), power-good flag with glitch filtering, and rugged HSOIC-8 package with PowerPAD™ thermal pad.
Technical Context
The LMR33640ADDAR implements peak-current-mode control with automatic PFM/PWM mode transition to maintain high light-load efficiency. Its internal 5-V LDO powers control circuitry and supports PG flag logic, while valley and peak current limiting plus hiccup-mode short-circuit protection ensure robust operation under overload.
It features an integrated zero-current detector for diode-emulation mode (DEM) at light loads, cycle-by-cycle current limit, thermal shutdown at 165°C, and input UVLO tied to VCC regulation - all enabled within a single 8-pin HSOIC package with dedicated AGND/PGND separation and BOOT-SW bootstrap capacitor routing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.8 V to 36 V - supports wide-VIN industrial supplies including 24-V rail and automotive battery transients. |
| Output Current | 4 A continuous - sufficient for powering FPGA I/O banks, microcontroller cores, or servo gate drivers. |
| Switching Frequency | 400 kHz - balances EMI performance and inductor size; avoids AM radio band and enables compact magnetics. |
| Feedback Reference | 1.0 V ±1.5% - enables precise output regulation across temperature and line/load variations. |
| Quiescent Current | 24 µA typical - minimizes standby power loss in always-on industrial controllers and sensors. |
| Shutdown Current | 5 µA - ensures ultra-low system-level leakage during deep sleep or fault lockout. |
| Thermal Shutdown | 165°C - protects MOSFETs and bond wires during sustained overload or poor PCB heatsinking. |
Pinout & Package
The LMR33640ADDAR is housed in an 8-pin HSOIC (DDA) package measuring 5.00 mm × 4.00 mm, featuring an exposed thermal pad on the bottom for direct soldering to PCB ground plane - critical for achieving RθJB = 13.6°C/W and sustaining 4-A load at 125°C ambient.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PGND (Pin 1) | Power ground return | Low-impedance path for high-frequency switch-node current; must connect directly to thermal pad and bulk input capacitor. |
| VIN (Pin 2) | Main input supply | Accepts 3.8–36 V; requires local 10-µF ceramic capacitor placed adjacent to pin with minimal loop area to PGND. |
| EN (Pin 3) | Enable control input | Logic-compatible input with precision thresholds (1.231 V typ ON); supports external UVLO via resistor divider. |
| PG (Pin 4) | Open-drain power-good flag | Signals regulated output status; requires external pull-up; includes 170-µs glitch filter to reject transient dips. |
| FB (Pin 5) | Feedback voltage sense | Monitors resistive divider output; 1.0-V reference sets VOUT = 1.0 × (1 + RFBT/RFBB). |
| VCC (Pin 6) | Internal 5-V LDO output | Powers internal circuitry; not for external loading; requires 1-µF bypass capacitor to PGND. |
| BOOT (Pin 7) | Bootstrap supply | Drives high-side MOSFET gate; connects to SW via 100-nF ceramic capacitor for charge replenishment. |
| SW (Pin 8) | Switch node | Connects to inductor; carries high dv/dt switching waveform; layout demands shortest possible trace to minimize EMI. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated compensation | Eliminates external Type-II/III compensation network - reduces BOM count by ≥3 components and accelerates design validation. |
| Auto PFM/PWM mode transition | Maintains >85% efficiency at 1-mA load while delivering full 4-A capability - ideal for systems with dynamic duty cycles like HVAC controllers. |
| Pin compatibility across family | Shares identical 8-pin HSOIC footprint with LMR33610/20/30 and LMR36510/20 - enables scalable power design without PCB respin. |
| Functional safety documentation support | Includes FIT rate data, failure mode analysis, and diagnostic coverage guidance - accelerates ISO 13849 or IEC 61508 system certification. |
| Hiccup-mode short-circuit protection | Limits average power dissipation during hard shorts to <1 W - prevents thermal runaway and enables safe auto-recovery after fault removal. |
Applications
| Motor Drive Power Rails | PLC Analog I/O Modules |
|---|---|
Use Scenario: Powering gate drivers and position sensor interfaces in drone ESCs and AC inverters requiring stable 5-V or 12-V rails under 4-A peak load. IC Role / Device Role / Timing Role: Primary buck regulator supplying isolated gate-driver bias and ADC reference voltage; operates at fixed 400-kHz switching frequency to avoid interference with motor commutation timing. Use Value: High efficiency (>95% at 2-A load) minimizes heat buildup in enclosed motor housings; thermal shutdown at 165°C prevents damage during stall conditions. | Use Scenario: Generating 3.3-V and 5-V supplies for analog front-end circuits and communication ICs in programmable logic controller backplanes. IC Role / Device Role / Timing Role: System power management IC providing regulated outputs with power-good signaling to coordinate CPU reset and FPGA configuration sequencing. Use Value: Precision enable threshold (1.231 V) enables accurate input UVLO for brownout detection; PG flag with 170-µs glitch filter prevents false resets during relay switching transients. |
| HVAC Control Panels | Elevator Main Control Units |
Use Scenario: Delivering 24-V auxiliary power to fan controllers and damper actuators in building automation systems operating from 24-V DC distribution bus. IC Role / Device Role / Timing Role: Wide-input buck converter stepping down 24-V bus to 12-V or 5-V for microcontrollers and CAN transceivers; uses PFM mode during idle periods to extend battery backup runtime. Use Value: 5-µA shutdown current extends backup battery life; –40°C to +125°C junction rating ensures reliability in unconditioned mechanical rooms. | Use Scenario: Supplying 5-V logic power to safety-critical elevator door monitoring and brake control modules connected to 36-V traction battery. IC Role / Device Role / Timing Role: Functional-safety-capable DC/DC converter providing redundant power with power-good confirmation and thermal derating alerts. Use Value: Documentation support for functional safety design reduces ASIL-B compliance effort; hiccup-mode protection prevents fire hazard during wiring faults. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMR33640DDDA | Same 4-A rating but 1-MHz switching frequency - higher core losses, smaller inductor, increased EMI risk. | Better suited for space-constrained designs where inductor height is limited; less optimal for noise-sensitive analog sections. | Select DDDA for compact layouts needing faster transient response; retain ADDAR for lower EMI and higher efficiency at medium loads. |
| LMR33630ADDAR | 3-A rated variant in identical HSOIC-8 package - lower RDS(on) (HS: 85 mΩ, LS: 58 mΩ) but reduced current headroom. | Appropriate for cost-optimized systems with ≤3-A steady-state load; shares same PCB footprint and layout. | Choose LMR33630ADDAR when peak load stays below 3 A - reduces thermal margin requirement and simplifies heatsinking. |
Compared with LMR33640DDDA and LMR33630ADDAR, the LMR33640ADDAR offers optimal balance of 4-A capability, 400-kHz EMI profile, and thermal robustness - making it preferred for industrial applications demanding reliability over miniaturization or marginal cost savings.
Availability
LMR33640ADDAR is available at Aetrix Electronics and suitable for motor drive systems, factory automation PLCs, and wide-VIN DC/DC power supplies requiring stable component supply across multi-year production cycles.
Supply support for LMR33640ADDAR 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 - serving industrial, automotive, and communications markets since 1930.
The LMR33640ADDAR belongs to TI's SIMPLE SWITCHER® family of easy-to-use DC/DC converters, engineered specifically for rugged industrial environments where reliability, wide input range, and simplified design are mandatory.
FAQ
What is the switching frequency of the LMR33640ADDAR?
The LMR33640ADDAR operates at a fixed 400-kHz switching frequency. This value is factory-trimmed and not user-adjustable. It provides a practical trade-off between inductor size, efficiency, and EMI performance - enabling use of standard low-DCR shielded power inductors while avoiding the AM broadcast band. The 400-kHz option is designated by the "ADDA" suffix in the part number, distinguishing it from the 1-MHz "DDDA" variant.
Does the LMR33640ADDAR require external compensation components?
No, the LMR33640ADDAR integrates full Type-II compensation circuitry internally. This eliminates the need for external compensation capacitors and resistors typically required in traditional current-mode buck controllers. As a result, the LMR33640ADDAR achieves stable operation with only five external components: input capacitor, output capacitor, power inductor, and two feedback resistors - significantly reducing design time and board area.
How does the power-good (PG) flag on the LMR33640ADDAR behave during startup?
During startup, the LMR33640ADDAR asserts the open-drain PG flag high approximately 4 ms after EN is pulled above its rising threshold (1.231 V). This delay ensures output voltage has settled within regulation before signaling "power good." The flag remains high as long as FB voltage stays between 92% and 107% of the 1.0-V reference, with built-in 170-µs glitch filtering to ignore brief transients. If EN is pulled low, PG is forced low immediately.
What thermal performance can be expected from the LMR33640ADDAR in an HSOIC-8 package?
In the HSOIC-8 (DDA) package, the LMR33640ADDAR achieves a junction-to-board thermal resistance (RθJB) of 13.6°C/W when the exposed thermal pad is properly soldered to a minimum 1-in² copper pour on the PCB. With adequate copper area and airflow, it sustains 4-A output continuously at +85°C ambient. Thermal shutdown activates at 165°C junction temperature, with recovery at 148°C - protecting against sustained overload or inadequate heatsinking.
Is the LMR33640ADDAR pin-compatible with other members of the SIMPLE SWITCHER® family?
Yes, the LMR33640ADDAR is pin-to-pin compatible with LMR33610ADDAR, LMR33620ADDAR, and LMR33630ADDAR (all 36-V, 1-A to 3-A variants), as well as LMR36510ADDAR and LMR36520ADDAR (65-V, 1-A and 2-A variants). This allows seamless scalability across power levels using identical PCB layout - reducing design reuse effort and qualification time for multi-tier product families.
LMR33640ADDAR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-PowerSOIC (0.154", 3.90mm 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):
- 3.8V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 1V
- Voltage - Output (Max):
- 24V
- Current - Output:
- 4A
- Frequency - Switching:
- 400kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO PowerPad
LMR33640ADDAR FAQ
1.How can I place an order for LMR33640ADDAR through Aetrix?
Please submit a Request for Quotation (RFQ) for LMR33640ADDAR 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 LMR33640ADDAR reliable?
The price and inventory of LMR33640ADDAR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LMR33640ADDAR is usually 5 days.
3.What payment methods are accepted for LMR33640ADDAR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LMR33640ADDAR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LMR33640ADDAR?
LMR33640ADDAR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LMR33640ADDAR 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 LMR33640ADDAR?
For technical support, including LMR33640ADDAR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LMR33640ADDAR requirements.
6.How does Aetrix verify that LMR33640ADDAR is sourced from the original manufacturer or authorized distributors?
All LMR33640ADDAR 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 LMR33640ADDAR meets industry standards.
7.What is the process for return or replacement of LMR33640ADDAR?
All LMR33640ADDAR units undergo pre-shipment inspection (PSI). If there is an issue with LMR33640ADDAR, 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 LMR33640ADDAR part is unused and in its original packaging.
Return procedure for LMR33640ADDAR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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