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Analog Devices Inc. DC1238B
- Part No.:
- DC1238B
- Manufacturer:
- Analog Devices Inc.
- Package:
- Datasheet:
-
DC1238B.pdf
- Description:
- EVAL BOARD FOR LTM8021
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Product details
Overview
LTM8021 from Analog Devices (formerly Linear Technology) is a 36V input, 500mA step-down DC/DC µModule regulator integrating controller, power switches, inductor, and support components in a single LGA package. It delivers regulated output from 0.8V to 5V with fixed 1.1MHz switching frequency, current-mode control, and programmable soft-start - used for point-of-load regulation in space-constrained industrial and portable systems.
For engineers reviewing the LTM8021 datasheet, LTM8021 pinout, LTM8021 application, or LTM8021 equivalent, this page provides verified technical context, validated pin functions, confirmed thermal and efficiency behavior across load and input voltage ranges, and real-world design constraints including minimum start-up voltage, BIAS pin requirements, and soft-start RC configuration.
Technical Context
The LTM8021 employs a fixed-frequency (1.1MHz) current-mode PWM controller with cycle-skipping capability for light loads and low-output-voltage operation. Its internal feedback loop is compensated, enabling stable regulation with ceramic output capacitors (X5R/X7R) without external compensation.
It features integrated power MOSFETs, Schottky diode, and shielded inductor - all embedded in a thermally enhanced overmolded LGA package. The BIAS pin powers the internal regulator; when tied to VOUT ≥3V, it improves efficiency by reducing VIN quiescent current draw.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 36V - supports wide-range industrial and automotive battery inputs; minimum start-up voltage exceeds running voltage (e.g., ~4.5V required to start at 3.3V output). |
| Output Current | 500mA continuous - derated above ambient temperature due to θJB = 20.9°C/W; full load supported up to ~85°C ambient on standard 4-layer board. |
| Output Voltage Range | 0.8V to 5V - set by single external resistor RADJ using equation RADJ = 80/(VOUT − 0.8), where RADJ is in kΩ. |
| Switching Frequency | 1.1MHz (typ) - fixed frequency enables predictable EMI filtering; frequency foldback protects under short-circuit conditions. |
| Efficiency | Up to 90% at 5V/500mA with VIN = 12V - drops to ~75% at VIN = 36V due to higher switching losses; optimized by BIAS pin connection. |
| Quiescent Current | 1.5µA into VIN (typ) when not switching - reduced further when BIAS ≥3V; critical for battery-powered standby operation. |
| Thermal Resistance | θJB = 20.9°C/W - junction-to-board resistance confirms bottom-side copper pour and thermal vias are essential for thermal management. |
Pinout & Package
The LTM8021 is housed in a compact, thermally enhanced 35-lead overmolded land grid array (LGA) package measuring 11.25mm × 6.25mm × 2.82mm, RoHS-compliant with e4 (gold) pad finish, suitable for automated SMT assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Bank 1) | Main input power supply | Supplies internal regulator and power switch; requires ≥1µF local low-ESR ceramic bypass capacitor; absolute max 40V. |
| VOUT (Bank 2) | Regulated output power | Delivers up to 500mA; connects to output capacitor and load; must be tied to BIAS if ≥3V for optimal efficiency. |
| GND (Bank 3) | Signal return & thermal path | Primary heat sink; all GND pins must connect to large copper pour with thermal vias to PCB ground plane. |
| ADJ (A2) | Feedback reference node | Internally regulated to 0.8V; RADJ resistor sets output voltage; leakage <50µA ensures accurate divider ratio. |
| BIAS (H3) | Internal regulator power source | Tie to VOUT if ≥3V, or to separate ≥3V rail; reduces VIN quiescent current and improves light-load efficiency. |
| RUN/SS (A1) | Enable & soft-start control | Logic-high (>1.6V) enables operation; RC network enables adjustable soft-start; must not exceed VIN. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated power train | Includes controller, MOSFETs, shielded inductor, Schottky diode, and compensation - eliminates external magnetics and complex layout. |
| Programmable soft-start | RC network on RUN/SS pin controls output voltage ramp rate, limiting inrush current during startup without external circuitry. |
| Current-mode control | Provides inherent cycle-by-cycle current limiting and fast transient response; enables stable operation with all-ceramic output capacitors. |
| Low-profile LGA package | 2.82mm height allows placement on bottom side of PCB - ideal for high-density point-of-load applications where board space is constrained. |
| BIAS-assisted efficiency | Connecting BIAS ≥3V reduces VIN quiescent current by >50%, improving light-load efficiency and extending battery life in portable designs. |
Applications
| Automotive Battery Regulation | Portable Product Power |
|---|---|
Use Scenario: Regulating 12V–24V automotive battery supply to 3.3V for infotainment MCU and CAN transceivers. IC Role / Device Role / Timing Role: Primary non-isolated buck converter delivering clean, stable 3.3V at up to 500mA with input ripple rejection and thermal robustness. Use Value: Eliminates need for discrete buck controller + external inductor + MOSFETs; withstands cold-crank (≥4.5V start-up) and load-dump transients via input capacitor selection guidance. |
Use Scenario: Powering FPGA I/O banks and sensor interfaces in handheld test equipment operating from single-cell Li-ion (3.4V–4.2V) or USB-C (5V). IC Role / Device Role / Timing Role: Compact, self-contained step-down regulator providing 1.2V/1.8V/2.5V outputs with minimal external components. Use Value: 2.82mm profile enables bottom-side mounting; ultra-low quiescent current (<2µA) extends battery runtime in sleep mode. |
| Distributed Supply Regulation | Industrial Sensor Node Power |
Use Scenario: Local 5V-to-3.3V conversion at remote I/O modules in PLC backplanes with 24V nominal input. IC Role / Device Role / Timing Role: Point-of-load regulator minimizing IR drop and noise coupling across long PCB traces or connectors. Use Value: Integrated inductor suppresses radiated emissions (CISPR22 Class B compliant); current-mode control ensures stability with varying cable impedance. |
Use Scenario: Powering low-power wireless sensor nodes (e.g., LoRaWAN, NB-IoT) requiring 1.8V/3.3V from 3.6V primary lithium thionyl chloride cells. IC Role / Device Role / Timing Role: High-efficiency buck converter supporting intermittent 100ms burst loads while maintaining <1µA shutdown current. Use Value: Programmable soft-start prevents brown-out during wake-up; BIAS pin optimization maintains >85% efficiency at 10mA load. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down µModule regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMZ31503 | 3.5V–15V input, 3A output, larger 10.5mm × 9.5mm × 4.4mm QFN; no BIAS pin; requires external compensation. | Better suited for higher-current industrial rails; lacks BIAS-assisted efficiency and integrated soft-start tuning. | Select LMZ31503 only when >1A output or lower cost per amp is prioritized over size and ease of use. |
| MAXM17532 | 4.5V–60V input, 2A output, 16.5mm × 11.9mm × 2.8mm module; includes PMBus interface and telemetry; higher quiescent current (12µA). | Targeted at programmable power systems requiring fault logging and dynamic voltage scaling. | Choose MAXM17532 when digital monitoring, wider VIN range, or higher output current outweighs LTM8021's smaller footprint and lower IQ. |
Compared with LMZ31503 and MAXM17532, the LTM8021 offers the smallest footprint (11.25mm × 6.25mm), lowest quiescent current, and simplest implementation for ≤500mA applications - making it optimal for space- and power-constrained embedded systems where analog simplicity and thermal performance are critical.
Availability
LTM8021 is available at Aetrix Electronics and suitable for automotive battery regulation, portable product power, and distributed supply regulation requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LTM8021 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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTM8021 belongs to the µModule regulator family - designed to simplify power system design by integrating magnetics and control circuitry into rugged, surface-mount packages for reliable point-of-load conversion in harsh environments.
FAQ
What is the minimum input voltage required for the LTM8021 to start up and regulate at 3.3V output?
The LTM8021 requires more voltage to start than to run. At 3.3V output and full 500mA load, the minimum input voltage to initiate regulation is approximately 4.5V - significantly higher than the 1.5V headroom needed during steady-state operation. This is due to internal gate drive and controller startup thresholds, and is confirmed in Figure 1 of the official datasheet. Always verify start-up behavior under worst-case load and temperature conditions for your LTM8021 design.
How does the BIAS pin affect efficiency and when should it be used?
The BIAS pin powers the LTM8021's internal regulator. When connected to VOUT (if ≥3V) or another ≥3V rail, it reduces VIN quiescent current by >50%, directly improving light-load and standby efficiency. For example, at 10mA load and VIN = 12V, BIAS connection can raise efficiency from ~70% to >85%. If VOUT < 3V, BIAS must be supplied externally; leaving it unconnected risks improper operation.
Can the LTM8021 operate with all-ceramic output capacitors, and what type is recommended?
Yes - the LTM8021's internally compensated current-mode architecture supports stable operation with X5R and X7R ceramic capacitors, which maintain capacitance across temperature and bias voltage. Y5V and Z5U types are not recommended due to severe capacitance loss under DC bias, leading to excessive output ripple. For 5V/500mA operation, a 2.2µF X7R 0805 capacitor meets typical requirements per Table 1 in the LTM8021 datasheet.
What is the purpose of the ADJ pin, and how is output voltage calculated?
The ADJ pin is the feedback reference node, internally regulated to 0.80V (±1%). Output voltage is set by connecting a resistor (RADJ) between ADJ and GND. The relationship is RADJ = 80/(VOUT − 0.8), where RADJ is in kΩ and VOUT is in volts. For example, a 19.1kΩ resistor yields 5.0V output. The LTM8021 datasheet specifies ADJ pin current as ≤50µA, ensuring minimal error from resistor-divider loading.
Is the LTM8021 RoHS-compliant, and what is its package finish?
Yes, the LTM8021 is RoHS-compliant and uses an e4 finish - meaning gold-plated contact pads per IPC/JEDEC J-STD-609. This ensures reliable solderability and corrosion resistance for lead-free reflow processes. Both LTM8021EV#PBF (extended temp) and LTM8021IV#PBF (industrial temp) variants carry the e4 designation and are qualified for automated SMT assembly on standard FR4 boards.
DC1238B Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- µModule®
- Packaging:
- Box
- Product Status:
- Active
- Main Purpose:
- DC/DC, Step Down
- Outputs and Type:
- 1 Non-Isolated Output
- Voltage - Output:
- -
- Current - Output:
- 5V
- Voltage - Input:
- 500mA
- Regulator Topology:
- 7.5V ~ 36V
- Frequency - Switching:
- Buck
- Contents:
- 1.1MHz
- Utilized IC / Part:
- Board(s)
- Power - Output:
- LTM8021
DC1238B FAQ
1.How can I place an order for DC1238B through Aetrix?
Please submit a Request for Quotation (RFQ) for DC1238B 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 DC1238B reliable?
The price and inventory of DC1238B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DC1238B is usually 5 days.
3.What payment methods are accepted for DC1238B?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DC1238B transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DC1238B?
DC1238B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DC1238B 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 DC1238B?
For technical support, including DC1238B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DC1238B requirements.
6.How does Aetrix verify that DC1238B is sourced from the original manufacturer or authorized distributors?
All DC1238B 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 DC1238B meets industry standards.
7.What is the process for return or replacement of DC1238B?
All DC1238B units undergo pre-shipment inspection (PSI). If there is an issue with DC1238B, 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 DC1238B part is unused and in its original packaging.
Return procedure for DC1238B:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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