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Analog Devices Inc. LT1933IDCB#TRMPBF
- Part No.:
- LT1933IDCB#TRMPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 6-WFDFN Exposed Pad
- Datasheet:
-
LT1933IDCB#TRMPBF.pdf
- Description:
- IC REG BUCK ADJ 600MA 6DFN
- Quantity:
- Payment:
- Shipping:
Inventory:722
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Product details
Overview
LT1933IDCB#TRMPBF from Analog Devices (formerly Linear Technology) is a 500kHz, current-mode PWM step-down DC/DC converter with an integrated 0.75A bipolar NPN power switch in a 6-lead 2mm × 3mm DFN package. It operates from 3.6V to 36V input, delivers up to 600mA at 3.3V or 5V output, and features internal compensation, soft-start, and <2μA shutdown current - ideal for automotive battery regulation and industrial distributed supplies.
For engineers reviewing the LT1933IDCB#TRMPBF datasheet, LT1933IDCB#TRMPBF pinout, LT1933IDCB#TRMPBF application, or LT1933IDCB#TRMPBF equivalent, key selection criteria include its fixed 500kHz switching frequency, 1.245V feedback reference, BOOST pin voltage headroom requirement, thermal performance in the DCB package (θJC = 12°C/W), and compatibility with ceramic input/output capacitors and low-ESR catch diodes.
Technical Context
The LT1933IDCB#TRMPBF implements constant-frequency current-mode control using an internal RS flip-flop oscillator and slope-compensated current sensing. Its VC node serves as the error amplifier output and current limit clamp point, with active soft-start implemented via SHDN pin voltage ramping.
It uses a bipolar NPN switch driven from either VIN or the BOOST pin, requiring an external boost capacitor and fast diode to generate ~2.3V above SW for full saturation. Frequency foldback activates when FB voltage drops below 1.1V, reducing switching frequency to 55kHz under overload or startup conditions to limit peak inductor current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 36V - supports unregulated wall adapters, 24V industrial rails, and automotive batteries with cold-crank margin. |
| Switching Frequency | Fixed 500kHz (typ.) - enables use of compact 22–33μH inductors and low-ESR ceramic capacitors. |
| Output Current | 600mA continuous - verified at 3.3V from 12–36V input and 5V from 16–36V input per datasheet test conditions. |
| Feedback Reference | 1.245V (±20mV) - sets output voltage via resistor divider; R2 = 10kΩ recommended for minimal bias error. |
| Shutdown Current | <2μA - ensures true output disconnect and ultra-low quiescent drain in battery-powered systems. |
| Max Duty Cycle | 94% - limits minimum input voltage required for regulation; e.g., ≥4.5V for 3.3V output. |
| Thermal Resistance | θJC = 12°C/W - requires exposed pad (Pin 7) soldered to PCB ground plane for reliable 125°C operation. |
Pinout & Package
The LT1933IDCB#TRMPBF is housed in a 6-lead (2mm × 3mm × 0.75mm) plastic DFN package with exposed thermal pad (Pin 7) that must be soldered to PCB ground for thermal and electrical integrity. Pin numbering follows standard DFN top-view orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BOOST (Pin 1) | Charge pump drive node | Must be ≥2.3V above SW for full switch saturation; connects to external 0.1μF cap + fast diode (e.g., 1N4148). |
| GND (Pin 2 & Exposed Pad) | Power and signal reference | Primary return path for switch current, feedback divider, and internal regulator; exposed pad is mandatory GND connection. |
| FB (Pin 3) | Voltage sense input | Regulated to 1.245V; sets output via R1/R2 divider; bias current ≤120nA minimizes divider error. |
| SHDN (Pin 4) | Enable/soft-start control | Logic-high (≥2.3V) enables operation; pulled low disables converter and reduces IQ to <2μA; RC network enables controlled start-up. |
| VIN (Pin 5) | Main power input | Supplies internal regulator and switch driver; requires local 2.2μF X7R/X5R ceramic bypass within 3mm. |
| SW (Pin 6) | Switch node | Connects to inductor, catch diode cathode, and boost capacitor anode; carries high di/dt pulsed current. |
Key Features
| Feature | Design Value |
|---|---|
| Internally compensated control loop | Eliminates need for external compensation components - simplifies layout and ensures stability with ceramic output capacitors. |
| Cycle-by-cycle current limiting | Protects against shorted outputs by clamping switch current at 0.75A (min), with slope compensation preventing subharmonic oscillation. |
| Wide input range with UVLO | Undervoltage lockout triggers at ~3.35V, preventing erratic operation during brownout or cold-crank conditions in automotive systems. |
| Low-profile DFN package | 2mm × 3mm footprint with 0.75mm height enables space-constrained designs such as portable instrumentation and modular PLC I/O. |
| Frequency foldback protection | Reduces switching frequency to 55kHz when FB voltage falls below 1.1V - limits peak inductor current during overload or startup faults. |
Applications
| Automotive Battery Regulation | Industrial Control Supplies |
|---|---|
Use Scenario: Regulating 12V/24V vehicle battery rail to stable 3.3V or 5V for microcontrollers and CAN transceivers in engine control units. IC Role / Device Role / Timing Role: Primary buck converter providing isolated, ripple-controlled power domain with cold-crank tolerance down to 3.6V input. Use Value: Enables direct connection to battery without pre-regulator; <2μA shutdown current extends key-off battery life. | Use Scenario: Powering fieldbus interface ICs (e.g., RS-485 transceivers) and analog sensor front-ends in programmable logic controllers. IC Role / Device Role / Timing Role: Point-of-load regulator converting 24V industrial supply to clean 5V for noise-sensitive communication circuits. Use Value: 500kHz operation allows small magnetics; DFN package fits dense backplane layouts; thermal pad ensures reliability at 85°C ambient. |
| Wall Transformer Regulation | Battery-Powered Equipment |
Use Scenario: Replacing linear regulators in AC/DC adapter-based devices (e.g., medical monitors, POS terminals) to improve efficiency and reduce heat. IC Role / Device Role / Timing Role: Efficient step-down stage accepting unregulated 9–36V DC from off-line transformer secondaries. Use Value: 85%+ efficiency across load range eliminates heatsinks; soft-start prevents inrush into large output caps. | Use Scenario: Supplying 3.3V to ARM Cortex-M microcontrollers and BLE radios in handheld test equipment with Li-ion battery input. IC Role / Device Role / Timing Role: Main system regulator operating from 3.6–4.2V battery, delivering 500mA with low-noise output and fast transient response. Use Value: Internal compensation and ceramic-capacitor compatibility minimize BOM count; shutdown mode extends runtime during sleep intervals. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3605EDE#TRPBF | 4MHz synchronous buck, 600mA, 2.5–5.5V input, integrated MOSFETs; smaller solution size but narrower input range. | Not suitable for 12–36V industrial or automotive inputs; better for low-voltage battery-powered systems only. | Select LTC3605EDE#TRPBF only if input is ≤5.5V and board area is critical; LT1933IDCB#TRMPBF remains preferred for wide-input legacy designs. |
| TPS54302DDCR | 3.5V–28V input, 3A synchronous buck, 500kHz, integrated FETs; higher current rating and wider temp range (–40°C to 125°C). | Requires external compensation; larger 8-pin SO PowerPAD package; higher quiescent current (~25μA) than LT1933's <2μA shutdown. | Choose TPS54302DDCR for higher output current or synchronous efficiency needs; retain LT1933IDCB#TRMPBF where ultra-low shutdown IQ or DFN footprint is mandatory. |
Compared with LTC3605EDE#TRPBF and TPS54302DDCR, the LT1933IDCB#TRMPBF offers unique advantages in ultra-low shutdown current, bipolar switch robustness against ESD/transients, and proven compatibility with legacy 22–33μH inductor footprints - making it optimal for cost-sensitive, wide-input, low-quiescent industrial and automotive modules.
Availability
LT1933IDCB#TRMPBF is available at Aetrix Electronics and suitable for automotive battery regulation, industrial control supplies, and wall transformer regulation requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT1933IDCB#TRMPBF 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
Analog Devices acquired Linear Technology in 2017 and maintains full technical and manufacturing continuity for all Linear power products.
The LT1933 belongs to Linear's legacy high-voltage buck regulator family, designed specifically for rugged, wide-input industrial and automotive power conversion where bipolar switch reliability and simple external component count are prioritized over synchronous efficiency.
FAQ
What is the maximum input voltage rating for the LT1933IDCB#TRMPBF?
The absolute maximum input voltage (VIN) for the LT1933IDCB#TRMPBF is 36V. Exceeding this value risks permanent damage. The BOOST pin has a separate 43V absolute maximum rating, and its voltage relative to SW must not exceed 20V. For reliable operation, design inputs to stay within 3.6V–36V, respecting both UVLO turn-on threshold (~3.35V) and maximum duty cycle constraints.
Does the LT1933IDCB#TRMPBF require external compensation components?
No, the LT1933IDCB#TRMPBF is internally compensated. Its control loop is designed to remain stable with standard ceramic output capacitors (e.g., 22μF X7R) and typical inductor values (22–33μH), eliminating the need for external compensation networks. This simplifies layout and reduces BOM count while maintaining phase margin across operating conditions.
How is soft-start implemented on the LT1933IDCB#TRMPBF?
Soft-start on the LT1933IDCB#TRMPBF is implemented via the SHDN pin: applying a slow-rising voltage (e.g., using a series resistor and capacitor to GND) ramps the internal VC node, limiting peak inductor current during startup. A typical 15kΩ resistor and 0.1μF capacitor yields ~1.5ms ramp time, reducing input surge and output overshoot without additional circuitry.
Can the LT1933IDCB#TRMPBF operate with a 3.3V input?
No - the LT1933IDCB#TRMPBF has a minimum operating input voltage of ~3.35V due to undervoltage lockout (UVLO). At 3.3V input, the device will not start or sustain regulation. For 3.3V-input applications, consider alternatives like the LTC3605EDE#TRPBF or TPS54302DDCR, which support lower VIN thresholds.
What is the function of the exposed pad (Pin 7) on the LT1933IDCB#TRMPBF DFN package?
The exposed pad (Pin 7) on the LT1933IDCB#TRMPBF is electrically and thermally connected to GND. It must be soldered to a PCB copper pour tied to the system ground plane to ensure proper thermal dissipation (θJC = 12°C/W) and low-impedance return path for high-current switch node transients. Omitting this connection risks thermal shutdown or instability.
LT1933IDCB#TRMPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 6-WFDFN Exposed Pad
- 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):
- 3.6V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 1.245V
- Voltage - Output (Max):
- 33.84V
- Current - Output:
- 600mA
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 6-DFN (2x3)
LT1933IDCB#TRMPBF FAQ
1.How can I place an order for LT1933IDCB#TRMPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1933IDCB#TRMPBF 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 LT1933IDCB#TRMPBF reliable?
The price and inventory of LT1933IDCB#TRMPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1933IDCB#TRMPBF is usually 5 days.
3.What payment methods are accepted for LT1933IDCB#TRMPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1933IDCB#TRMPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1933IDCB#TRMPBF?
LT1933IDCB#TRMPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1933IDCB#TRMPBF 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 LT1933IDCB#TRMPBF?
For technical support, including LT1933IDCB#TRMPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1933IDCB#TRMPBF requirements.
6.How does Aetrix verify that LT1933IDCB#TRMPBF is sourced from the original manufacturer or authorized distributors?
All LT1933IDCB#TRMPBF 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 LT1933IDCB#TRMPBF meets industry standards.
7.What is the process for return or replacement of LT1933IDCB#TRMPBF?
All LT1933IDCB#TRMPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1933IDCB#TRMPBF, 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 LT1933IDCB#TRMPBF part is unused and in its original packaging.
Return procedure for LT1933IDCB#TRMPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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