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Analog Devices Inc. LTC3538EDCB
- Part No.:
- LTC3538EDCB
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3538EDCB.pdf
- Description:
- IC REG BUCK BOOST ADJ 800MA 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,576
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Product details
Overview
LTC3538EDCB from Analog Devices (formerly Linear Technology) is a synchronous 4-switch buck-boost DC/DC converter IC designed for single-cell Li-Ion, multi-cell alkaline, or NiMH battery-powered systems where input voltage may fall above, below, or equal to the regulated output. It delivers up to 800mA continuous output current, operates at a fixed 1MHz switching frequency, features 0.17Ω NMOS and 0.2Ω PMOS internal switches, and supports 1.8V–5.25V adjustable output in an 8-lead DFN package. It is used in miniature hard disk drives requiring stable 3.3V rail generation across wide battery discharge ranges.
For engineers reviewing the LTC3538EDCB datasheet, LTC3538EDCB pinout, LTC3538EDCB application, or LTC3538EDCB equivalent, key selection criteria include its buck-boost topology with seamless mode transition, Burst Mode® operation for <35μA light-load quiescent current, output disconnect in shutdown, internal soft-start, and thermal/short-circuit protection - all critical for portable power management in space-constrained designs.
Technical Context
The LTC3538EDCB implements a proprietary four-switch synchronous buck-boost topology with continuous conduction across buck, buck-boost, and boost regions. Its control architecture uses a voltage-mode error amplifier (VC pin) to modulate duty cycles of internal NMOS (B/C) and PMOS (A/D) switches, enabling smooth transitions without output discontinuity when VIN crosses VOUT.
It integrates dual current-limit mechanisms: a 3.5A peak switch-A current limit with 50ns response and a 2A average input current limit via FB-pin sourcing. Reverse current limiting (500mA typical) prevents negative inductor current during fixed-frequency operation, while Burst Mode® dynamically disables switching to reduce quiescent current to 35μA at light loads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | 4-switch synchronous buck-boost - enables continuous regulation with VIN above, below, or equal to VOUT without external diodes or mode-switching artifacts. |
| Output Current | 800mA continuous - sufficient for μHDD, GPS receivers, and digital camera core rails powered from single Li-Ion cells. |
| Input Voltage Range | 2.4V to 5.5V - supports full discharge curve of 1-cell Li-Ion (2.7–4.2V) and multi-cell alkaline/NiMH stacks. |
| Output Voltage Range | 1.8V to 5.25V (adjustable via FB divider) - covers common logic rails (3.3V, 5V) and analog subsystems. |
| Switching Frequency | 1MHz fixed - minimizes inductor size (e.g., 3.3μH typical) and enables compact filter design while maintaining >90% efficiency at 200mA load. |
| Quiescent Current | 35μA in Burst Mode®, <5μA in shutdown - extends battery life in standby states for handheld devices. |
| Package | 8-lead (2mm × 3mm) DFN with exposed pad - thermally enhanced for 75°C/W junction-to-ambient, requires soldered GND pad for thermal and electrical integrity. |
Pinout & Package
Package: 8-lead plastic DFN (2mm × 3mm), 0.75mm height, exposed thermal pad (Pin 9, GND). Must be soldered to PCB ground plane for thermal performance and electrical stability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 8) | Input power supply connection | Accepts 2.4–5.5V; powers internal circuitry and supplies current to PMOS switch A; requires ≥4.7μF low-ESR ceramic bypass capacitor placed adjacent to pin. |
| SW1 (Pin 7) | Switch node for internal NMOS B and PMOS A | Connects to one end of power inductor; high dI/dt node requiring short, low-inductance PCB trace; optional Schottky diode to GND improves light-load efficiency. |
| SW2 (Pin 6) | Switch node for internal NMOS C and PMOS D | Connects to other end of power inductor and output capacitor; high dI/dt node; optional Schottky diode to VOUT reduces conduction loss in boost mode. |
| VOUT (Pin 5) | Regulated power output | Delivers up to 800mA; connects directly to low-ESR output capacitor (e.g., 22μF ceramic); return path must route to GND pin with minimal impedance. |
| FB (Pin 1) | Feedback input to error amplifier | Senses output voltage via resistive divider; sets VOUT = 1V × (1 + R1/R2); input bias current ≤50nA ensures accuracy with high-value dividers. |
| VC (Pin 2) | Error amplifier output | Controls switch duty cycle; loop compensation network (RZ/CZ1/CP1) connects here; pulling VC < 0.25V disables IC with 1.5μA shutdown current. |
| GND (Pin 3) | Analog and power ground reference | Small-signal ground for FB/VC/BURST; must connect to exposed pad (Pin 9) at single point to avoid noise coupling into feedback path. |
| BURST (Pin 4) | Mode select input | Logic-high (≥1.4V) enables Burst Mode® for ultra-low IQ; logic-low (≤0.4V) forces fixed-frequency PWM operation; input current ≤1μA. |
Key Features
| Feature | Design Value |
|---|---|
| Seamless buck-boost operation | Continuous transfer function across VIN/VOUT crossover eliminates output glitches during battery discharge, critical for real-time μHDD and GPS applications. |
| Burst Mode® efficiency optimization | Reduces quiescent current to 35μA at light loads while maintaining regulation, extending runtime in standby without sacrificing transient response. |
| Integrated power MOSFETs | 0.17Ω NMOS (B/C) and 0.2Ω PMOS (A/D) switches enable high efficiency (>90%) without external FETs or gate drivers, reducing BOM count and layout complexity. |
| Output disconnect in shutdown | Prevents reverse current flow from VOUT to VIN when disabled, protecting batteries and upstream sources in portable systems with shared power rails. |
| Comprehensive protection suite | Includes thermal shutdown, short-circuit protection, reverse current limiting (500mA), and dual-stage overcurrent limiting (peak + average) for robust field operation. |
Applications
| Miniature Hard Disk Drives (μHDD) | GPS Receivers |
|---|---|
Use Scenario: Powering 3.3V spindle motor and controller ICs from a single Li-Ion cell (2.7–4.2V) across full discharge cycle. IC Role / Device Role / Timing Role: Primary buck-boost regulator providing regulated 3.3V rail with seamless mode transition as battery voltage drops below 3.3V. Use Value: Maintains stable 3.3V output without brownouts during deep discharge, enabling reliable data access and motor control down to 2.4V input. |
Use Scenario: Generating clean 3.3V supply for RF front-end and baseband processor in handheld GPS units. IC Role / Device Role / Timing Role: Low-noise, high-efficiency DC/DC converter minimizing conducted EMI that could degrade GNSS signal acquisition. Use Value: 1MHz fixed frequency allows predictable filtering; Burst Mode® extends battery life during satellite search intervals with minimal output ripple. |
| Digital Cameras | Cellular Handsets |
Use Scenario: Supplying 3.3V to image sensor and ISP during burst capture, with rapid load transients from flash LED activation. IC Role / Device Role / Timing Role: High-current (800mA) buck-boost regulator supporting peak sensor power demands while maintaining regulation. Use Value: Internal 3.5A peak current limit and fast transient response prevent voltage droop during flash strobes, ensuring image integrity. |
Use Scenario: Providing 3.3V system rail from single-cell Li-Poly battery in feature phones with display backlight and audio codec. IC Role / Device Role / Timing Role: Compact, thermally efficient power solution meeting tight board area constraints in slim handset form factors. Use Value: 2mm × 3mm DFN package with exposed pad enables high power density; <5μA shutdown current preserves battery during long idle periods. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck-boost DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3440EDD | Lower 600mA output current; 3MHz switching frequency; no Burst Mode®; requires external compensation. | Less suitable for μHDD or high-pulse-load cameras due to reduced current capability and higher IQ in light-load conditions. | Select LTC3538EDCB when 800mA continuous output, Burst Mode® efficiency, or seamless VIN/VOUT crossover is required. |
| TPS63020DSJR | Higher 2A output current; 2.5MHz switching; integrated compensation; slightly larger 3mm × 2mm QFN package. | Better for high-current applications like portable medical devices, but less optimized for ultra-low-IQ portable standby. | Choose LTC3538EDCB for proven low-noise 1MHz operation and <35μA Burst Mode® in space-constrained consumer electronics. |
Compared with LTC3440EDD and TPS63020DSJR, the LTC3538EDCB offers superior light-load efficiency via Burst Mode®, tighter thermal performance in its 2mm × 3mm DFN, and smoother mode transitions - making it optimal for battery-powered μHDD, GPS, and digital imaging where regulation continuity and standby longevity are critical.
Availability
LTC3538EDCB is available at Aetrix Electronics and suitable for miniature hard disk drives, GPS receivers, digital cameras, and cellular handsets requiring stable component supply with guaranteed long-term manufacturability and consistent parametric performance.
Supply support for LTC3538EDCB 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 its precision analog and power management product lines. Linear Technology was renowned for high-performance DC/DC converters, references, and amplifiers targeting demanding industrial and portable applications.
The LTC3538EDCB belongs to Linear's buck-boost converter family engineered specifically for single-cell battery systems where input voltage varies across the output rail - emphasizing seamless regulation, low quiescent current, and compact integration for handheld electronics.
FAQ
What is the maximum continuous output current of the LTC3538EDCB?
The LTC3538EDCB delivers up to 800mA continuous output current under typical conditions (e.g., VOUT = 3.3V, VIN = 3.6V, TA = 25°C). This rating assumes proper thermal management using the exposed pad soldered to a PCB ground plane. Peak switch current capability reaches 3.5A, supporting transient loads without dropout.
Does the LTC3538EDCB support output voltages outside the 1.8V–5.25V range?
No - the LTC3538EDCB's feedback reference is fixed at 1.00V (±2%), and its internal error amplifier is specified only for output voltages between 1.8V and 5.25V. Attempting to set VOUT outside this range via external resistor dividers may result in regulation inaccuracy, instability, or failure to maintain regulation across temperature and load.
How does Burst Mode® operation affect output ripple on the LTC3538EDCB?
In Burst Mode®, the LTC3538EDCB delivers energy in discrete packets then sleeps, causing variable-frequency ripple typically ~2% peak-to-peak at light loads. This is inherent to the topology and not a defect. Ripple can be reduced by increasing output capacitance or adding a feed-forward capacitor across the upper FB divider resistor, as documented in the datasheet.
Can the LTC3538EDCB be used with input voltages below 2.4V?
No - the absolute minimum input voltage is 2.4V per Absolute Maximum Ratings. Operation below this risks improper startup, undefined regulation behavior, or failure to sustain output under load. The minimum start-up voltage is specified at 2.302V (typical), but reliable continuous operation requires VIN ≥ 2.4V.
What is the role of the exposed pad (Pin 9) on the LTC3538EDCB DFN package?
The exposed pad (Pin 9) is electrically and thermally connected to GND. It must be soldered to a PCB ground plane to ensure proper thermal dissipation (θJA = 75°C/W) and low-impedance grounding for internal power switches and analog circuitry. Leaving it unconnected degrades efficiency, increases junction temperature, and may cause instability or premature thermal shutdown.
LTC3538EDCB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck-Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.4V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 1.8V
- Voltage - Output (Max):
- 5.25V
- Current - Output:
- 800mA
- Frequency - Switching:
- 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (2x3)
LTC3538EDCB FAQ
1.How can I place an order for LTC3538EDCB through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3538EDCB 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 LTC3538EDCB reliable?
The price and inventory of LTC3538EDCB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3538EDCB is usually 5 days.
3.What payment methods are accepted for LTC3538EDCB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3538EDCB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3538EDCB?
LTC3538EDCB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3538EDCB 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 LTC3538EDCB?
For technical support, including LTC3538EDCB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3538EDCB requirements.
6.How does Aetrix verify that LTC3538EDCB is sourced from the original manufacturer or authorized distributors?
All LTC3538EDCB 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 LTC3538EDCB meets industry standards.
7.What is the process for return or replacement of LTC3538EDCB?
All LTC3538EDCB units undergo pre-shipment inspection (PSI). If there is an issue with LTC3538EDCB, 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 LTC3538EDCB part is unused and in its original packaging.
Return procedure for LTC3538EDCB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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