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Analog Devices Inc. LTC3538EDCB#TRMPBF
- Part No.:
- LTC3538EDCB#TRMPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3538EDCB#TRMPBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 800MA 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:167
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Product details
Overview
LTC3538EDCB#TRMPBF from Analog Devices (formerly Linear Technology) is a synchronous 4-switch buck-boost DC/DC converter IC designed for single-cell Li-Ion/Polymer or multi-cell alkaline/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 integrated 0.17Ω NMOS and 0.2Ω PMOS switches, and supports 1.8V–5.25V output voltage adjustment via external resistor divider. It is used in miniature hard disk drives requiring stable 3.3V rail from a varying 2.4V–4.2V battery source.
For engineers reviewing the LTC3538EDCB#TRMPBF datasheet, LTC3538EDCB#TRMPBF pinout, LTC3538EDCB#TRMPBF application, or LTC3538EDCB#TRMPBF equivalent, key selection criteria include its seamless buck-buck-boost mode transition, Burst Mode® operation enabling 35μA quiescent current, internal soft-start (1.5ms), <5μA shutdown current, and thermally enhanced 8-lead DFN (2mm × 3mm, 0.75mm height) package with exposed GND pad.
Technical Context
The LTC3538EDCB#TRMPBF implements a proprietary four-MOSFET synchronous topology that enables continuous conduction across buck, buck-boost, and boost regions without discontinuity or mode-hopping artifacts. Its voltage-mode PWM control uses the VC pin as an error amplifier output to directly modulate switch duty cycles, with phasing logic ensuring zero-voltage switching transitions during mode boundaries.
It integrates dual current-limit protection: a 3.5A peak input current limit with 50ns response and a 2A average input current limit enforced via FB pin current injection. Reverse current limiting (500mA typical) prevents output-to-input backfeed in fixed-frequency mode, while output disconnect in shutdown eliminates battery drain.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | 4-switch synchronous buck-boost - enables uninterrupted regulation when VIN crosses VOUT (e.g., Li-Ion discharge from 4.2V to 2.7V while maintaining 3.3V output). |
| Output Current | 800mA continuous - sufficient for μHDD spindle motors and logic rails in portable storage devices. |
| Input Voltage Range | 2.4V to 5.5V - supports single Li-Ion (2.9–4.2V), two alkaline/NiMH (2.4–3.6V), or USB 5V input with step-down capability. |
| Output Voltage Range | 1.8V to 5.25V - adjustable via external resistor divider; factory-trimmed feedback reference is 1.00V ±2%. |
| Switching Frequency | 1MHz fixed - minimizes inductor and capacitor size while balancing efficiency and EMI; no external clock required. |
| Quiescent Current | 35μA in Burst Mode - extends battery runtime in standby states of MP3 players and GPS receivers. |
| Shutdown Current | <5μA - ensures negligible battery leakage during system sleep or power-off. |
| Package | 8-lead DFN (2mm × 3mm, 0.75mm height) with exposed thermal pad - provides low θJA (75°C/W) for high-power-density layouts. |
Pinout & Package
The LTC3538EDCB#TRMPBF is housed in an 8-lead plastic DFN package (DCB) measuring 2mm × 3mm × 0.75mm, featuring an exposed GND pad (Pin 9) that must be soldered to PCB for thermal and electrical integrity. Pin pitch is 0.5mm; top marking is "LCRB".
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (Pin 1) | Feedback input to error amplifier | Connects to resistor divider tap from VOUT; sets output voltage per VOUT = 1V × (1 + R1/R2); input bias current ≤50nA enables high-resistor-divider use. |
| VC (Pin 2) | Error amplifier output | Controls switch duty cycle; pulling VC < 0.25V disables IC; compensation network (RZ/CZ1/CP1) connects here for loop stability. |
| GND (Pin 3) | Analog ground reference | Small-signal ground return for FB, VC, BURST; must connect to exposed pad via single-point star ground to avoid noise coupling. |
| 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. |
| VOUT (Pin 5) | Regulated power output | Delivers up to 800mA; requires low-ESR ceramic capacitor (e.g., 22μF X5R) placed adjacent to pin with short GND return path. |
| SW2 (Pin 6) | Switch node for internal MOSFETs C and D | Connects to inductor second terminal and optional Schottky diode cathode (to VOUT) for efficiency boost in boost/buck-boost modes. |
| SW1 (Pin 7) | Switch node for internal MOSFETs A and B | Connects to inductor first terminal and optional Schottky diode cathode (to GND) for efficiency boost in buck mode; high di/dt node. |
| VIN (Pin 8) | Main power input | Supplies IC bias and switch A; requires ≥4.7μF low-ESR ceramic bypass cap placed within 2mm of pin and GND. |
Key Features
| Feature | Design Value |
|---|---|
| Continuous buck-buck-boost transfer function | Eliminates output voltage glitch or regulation loss when VIN crosses VOUT - critical for battery-powered systems with wide discharge range. |
| Integrated 0.17Ω NMOS / 0.2Ω PMOS switches | Enables high-efficiency conversion without external FETs; reduces BOM count and layout complexity in space-constrained μHDD and handheld designs. |
| Burst Mode® operation | Reduces IQ to 35μA at light loads while maintaining regulation - extends usable battery capacity in intermittent-use applications like GPS receivers. |
| Internal soft-start (1.5ms) | Prevents inrush current and output overshoot during power-up; ensures controlled VOUT ramp regardless of load or output capacitance value. |
| Output disconnect in shutdown | Blocks reverse current flow from VOUT to VIN when disabled - protects battery from parasitic drain in powered-off state. |
| Thermal shutdown & short-circuit protection | Automatically disables IC if junction temperature exceeds 125°C or output is shorted - safeguards device and system under fault conditions. |
Applications
| Miniature Hard Disk Drives (μHDD) | MP3 Players |
|---|---|
|
Use Scenario: Powering 3.3V spindle motor and controller ASIC from a single Li-Ion cell (2.9–4.2V) during read/write and idle states. IC Role / Device Role / Timing Role: Primary buck-boost regulator providing stable 3.3V rail with seamless mode transition as battery discharges. Use Value: Enables full 800mA motor drive capability across entire battery range without voltage droop or brownout, extending playback time by 12% vs. fixed-buck solutions. |
Use Scenario: Generating 3.3V system rail for audio codec, flash memory, and display driver from 2× alkaline cells (2.4–3.6V). IC Role / Device Role / Timing Role: Main DC/DC converter operating in Burst Mode® during music decode pauses to minimize quiescent draw. Use Value: Achieves 35μA sleep current, doubling standby duration versus fixed-frequency alternatives while maintaining fast wake-up response. |
| Digital Cameras | Cellular Handsets |
|
Use Scenario: Supplying 2.8V image sensor and 3.3V processor core from shared Li-Po battery during burst capture and preview modes. IC Role / Device Role / Timing Role: Dual-rail capable regulator (via separate FB dividers) delivering precise, low-noise power with minimal ripple. Use Value: 1MHz fixed frequency avoids audible noise in audio circuits; 20mVpp output ripple at 500mA ensures clean sensor analog performance. |
Use Scenario: Providing 3.3V RF transceiver and 2.8V baseband processor supply from single-cell Li-Ion in GSM/UMTS handsets. IC Role / Device Role / Timing Role: High-efficiency buck-boost converter supporting dynamic load steps (e.g., TX burst) without output sag. Use Value: 800mA peak current and 1.5ms soft-start prevent VOUT dip during transmit events, improving RF signal integrity and call reliability. |
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 |
|---|---|---|---|
| MAX77827BEWI+T | Higher 1.2A output current; 2.5MHz switching; I²C programmable VOUT; no Burst Mode® - uses pulse-skipping instead. | Requires digital interface and firmware support; better suited for multi-rail PMIC integration than standalone replacement. | Select when programmability, higher current, or smaller inductors are prioritized over ultra-low IQ in sleep. |
| TPS63020DSJR | Lower 600mA output; 2.5MHz switching; 3.5μA shutdown current; integrated compensation - no VC pin for external loop tuning. | Lacks VC pin and Burst Mode®, limiting light-load efficiency optimization and custom loop design flexibility. | Choose for cost-sensitive, lower-current applications where simplified layout and guaranteed stability outweigh IQ and tuning needs. |
Compared with MAX77827BEWI+T and TPS63020DSJR, the LTC3538EDCB#TRMPBF offers superior light-load efficiency via Burst Mode®, direct VC-loop control for optimized transient response, and proven robustness in high-reliability μHDD deployments - making it preferred where battery life and analog performance are critical.
Availability
LTC3538EDCB#TRMPBF is available at Aetrix Electronics and suitable for miniature hard disk drives, MP3 players, digital cameras, cellular handsets, and GPS receivers requiring stable component supply with consistent parametric performance and long-term manufacturability.
Supply support for LTC3538EDCB#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 its precision analog and power management product lines. Linear pioneered high-performance DC/DC converters with proprietary topologies and low-noise regulation.
The LTC3538EDCB#TRMPBF belongs to Linear's high-efficiency buck-boost converter family, engineered specifically for battery-powered portable electronics where input voltage varies across the output setpoint - enabling single-supply operation without voltage doublers or LDO post-regulation.
FAQ
What is the maximum continuous output current of the LTC3538EDCB#TRMPBF?
The LTC3538EDCB#TRMPBF delivers up to 800mA continuous output current under typical conditions (TA = 25°C, VOUT = 3.3V, VIN = 3.6V). This rating assumes proper thermal management using the exposed GND pad and a 4-layer PCB with adequate copper area. Peak current capability reaches 1.4A before current limiting activates, but sustained operation above 800mA requires derating based on ambient temperature and airflow.
Does the LTC3538EDCB#TRMPBF support output voltages below 3.3V?
Yes, the LTC3538EDCB#TRMPBF supports output voltages from 1.8V to 5.25V via an external resistor divider connected to the FB pin. The internal feedback reference is precisely trimmed to 1.00V ±2%, so setting VOUT = 2.5V requires R1/R2 = 1.5 (e.g., R1 = 150kΩ, R2 = 100kΩ). Operation down to 1.8V is fully characterized and supported across the –40°C to 85°C temperature range.
How does Burst Mode® operation affect output voltage ripple on the LTC3538EDCB#TRMPBF?
In Burst Mode®, the LTC3538EDCB#TRMPBF delivers energy in short bursts and then sleeps, causing variable-frequency ripple typically around 2% peak-to-peak at light loads. This differs from fixed-frequency PWM ripple, which is deterministic and centered at 1MHz. Adding more output capacitance (e.g., increasing COUT from 22μF to 47μF) or using Type III compensation with a feed-forward capacitor across R1 reduces this ripple amplitude without disabling Burst Mode®.
Can the LTC3538EDCB#TRMPBF be used with a 5V USB input to generate 3.3V?
Yes, the LTC3538EDCB#TRMPBF accepts VIN from 2.4V to 5.5V, making it suitable for USB-powered 3.3V applications. In buck mode (VIN > VOUT), it achieves >92% efficiency at 500mA with 5V input. A typical application circuit uses a 3.3μH inductor and 22μF ceramic output capacitor. The BURST pin can be tied to GND for fixed-frequency operation to minimize conducted EMI in noise-sensitive USB peripherals.
What thermal considerations apply to the LTC3538EDCB#TRMPBF package?
The LTC3538EDCB#TRMPBF uses an 8-lead DFN (DCB) package with an exposed GND pad (Pin 9) that must be soldered to a thermal pad on the PCB. Thermal resistance is θJA = 75°C/W on a 4-layer board; θJC = 13.5°C/W to the exposed pad. To maintain TJ < 125°C at 800mA, ensure ≥200mm² of 2-oz copper connected to the pad via ≥4 thermal vias (0.3mm diameter), and avoid placing heat-generating components nearby.
LTC3538EDCB#TRMPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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#TRMPBF FAQ
1.How can I place an order for LTC3538EDCB#TRMPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3538EDCB#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 LTC3538EDCB#TRMPBF reliable?
The price and inventory of LTC3538EDCB#TRMPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3538EDCB#TRMPBF is usually 5 days.
3.What payment methods are accepted for LTC3538EDCB#TRMPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3538EDCB#TRMPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3538EDCB#TRMPBF?
LTC3538EDCB#TRMPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3538EDCB#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 LTC3538EDCB#TRMPBF?
For technical support, including LTC3538EDCB#TRMPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3538EDCB#TRMPBF requirements.
6.How does Aetrix verify that LTC3538EDCB#TRMPBF is sourced from the original manufacturer or authorized distributors?
All LTC3538EDCB#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 LTC3538EDCB#TRMPBF meets industry standards.
7.What is the process for return or replacement of LTC3538EDCB#TRMPBF?
All LTC3538EDCB#TRMPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3538EDCB#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 LTC3538EDCB#TRMPBF part is unused and in its original packaging.
Return procedure for LTC3538EDCB#TRMPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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