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Analog Devices Inc. LTC1625IS#PBF
- Part No.:
- LTC1625IS#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1625IS#PBF.pdf
- Description:
- IC REG CTRLR BUCK/BOOST 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:298
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Product details
Overview
LTC1625IS#PBF from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller that drives external N-channel MOSFETs without requiring a current-sense resistor. It features MOSFET VDS sensing, 150 kHz nominal oscillator frequency, ±1% 1.19 V reference, and supports output voltages from 1.19 V to VIN. It enables high-efficiency, high-current DC/DC conversion in battery-powered portable systems.
For engineers reviewing the LTC1625IS#PBF datasheet, LTC1625IS#PBF pinout, LTC1625IS#PBF application, or LTC1625IS#PBF equivalent, key selection considerations include its no-RSENSE current-mode architecture, forced continuous mode control via FCB pin, Burst Mode™ operation for light-load efficiency, programmable soft start, and dual N-MOSFET synchronous drive capability.
Technical Context
The LTC1625IS#PBF implements constant-frequency current-mode control using internal VDS sensing across the top MOSFET (via TK pin) to eliminate external sense resistors. Its error amplifier adjusts the ITH voltage (0–2.4 V range) to regulate peak inductor current against a 1.19 V reference, with load regulation of ±0.2% and line regulation of 0.01%/V.
It integrates a 5.2 V internal LDO (INTVCC) powered either from VIN or an external EXTVCC source ≥4.7 V, and supports synchronization over a 1.5:1 frequency range (100–225 kHz) via the SYNC pin. Fault protection includes foldback current limiting (150 mV → 30 mV threshold reduction), output overvoltage lockout at 1.28 V, and dropout recovery via a dedicated counter.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 3.7 V to 36 V - supports wide-input industrial and battery systems including 12 V, 24 V, and multi-cell Li-ion inputs. |
| VOUT Range | 1.19 V to VIN - enables adjustable low-voltage rails (e.g., 1.2 V, 1.8 V, 3.3 V, 5 V) and near-100% duty-cycle operation for low-dropout applications. |
| Oscillator Frequency | 135–165 kHz (typ. 150 kHz) - fixed-frequency operation with injection-lock synchronization up to 225 kHz for EMI control. |
| Reference Accuracy | ±1% at 1.19 V - ensures tight output voltage tolerance under varying load, line, and temperature conditions. |
| Shutdown Current | <30 µA - enables micropower shutdown for extended battery life in portable equipment. |
| Current Sense Threshold | 120–170 mV - sets maximum peak inductor current without external resistor; directly tied to RDS(ON) of top MOSFET. |
| Overvoltage Lockout | 1.24–1.32 V - protects downstream circuitry during transients or feedback failure by disabling top MOSFET. |
Pinout & Package
The LTC1625IS#PBF is housed in a 16-lead narrow SSOP package (GN package), with 0.15 mm lead thickness, 0.64 mm body width, and 0.05 mm pitch. Thermal resistance θJA = 130°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EXTVCC (1) | External INTVCC supply input | Enables high-efficiency power sourcing from converter output; switches INTVCC to EXTVCC when >4.7 V. |
| SYNC (2) | Oscillator synchronization input | Locks internal 150 kHz oscillator to external clock (100–225 kHz); enables EMI spread-spectrum or system clock alignment. |
| RUN/SS (3) | Run enable & soft-start control | Pull below 1.4 V to shut down; external capacitor sets ramp time (~1 s/µF) for controlled startup and supply sequencing. |
| FCB (4) | Forced continuous mode control | Tie to ground to disable Burst Mode and enforce continuous conduction-critical for secondary winding regulation. |
| ITH (5) | Error amplifier compensation node | 0–2.4 V control voltage sets current comparator threshold; used for loop compensation and transient response tuning. |
| SGND (6) | Signal ground reference | Return path for VOSENSE and feedback network; must be connected to COUT negative terminal to minimize noise coupling. |
| VOSENSE (7) | Output voltage feedback input | Accepts remote-sensed output or divider output; enables precision regulation independent of PCB trace IR drop. |
| VPROG (8) | Output voltage selection | Open = adjustable via external divider; 0 V = 3.3 V; INTVCC = 5 V - simplifies board-level configuration without rework. |
| PGND (9) | Power ground for bottom gate driver | Low-impedance return for bottom MOSFET source, CVCC, and CIN; must be star-connected to minimize ground bounce. |
| BG (10) | Bottom N-MOSFET gate driver | Drives bottom switch between PGND and INTVCC (5.2 V); supports logic-level MOSFETs with fast 50–150 ns transitions. |
| INTVCC (11) | Internal 5.2 V regulator output | Supplies gate drivers and internal circuitry; requires ≥4.7 µF tantalum decoupling to PGND for stability. |
| BOOST (12) | Bootstrap capacitor top rail | Connects to (+) terminal of bootstrap cap; swings from ~INTVCC −0.7 V to VIN + INTVCC for high-side gate drive. |
| TG (13) | Top N-MOSFET gate driver | Drives top switch referenced to SW node; swing amplitude = INTVCC − diode drop, enabling efficient high-side drive. |
| SW (14) | Switch node | Connects to inductor, bootstrap cap (−), and top MOSFET source; high dv/dt node requiring careful layout and minimal parasitic inductance. |
| TK (15) | Top MOSFET Kelvin sense | Direct connection to top MOSFET drain (separate from VIN) enables accurate VDS sensing and eliminates RSENSE. |
| VIN (16) | Main input supply | 3.7–36 V input; requires RC filter (4.7 Ω / 0.1 µF) for >3 A applications to suppress high-frequency noise. |
Key Features
| Feature | Design Value |
|---|---|
| No current-sense resistor required | Uses MOSFET VDS sensing via TK pin to eliminate 1–5% efficiency loss and PCB area associated with discrete sense resistors. |
| Programmable soft start | Capacitor on RUN/SS pin provides controlled output ramp-up (~1 s/µF), preventing inrush current and enabling precise power sequencing. |
| Pin-selectable output voltage | VPROG pin selects 3.3 V (0 V), 5 V (INTVCC), or adjustable (open) - reduces BOM variants and simplifies design reuse across platforms. |
| Forced continuous mode control | FCB pin disables Burst Mode to maintain regulation on auxiliary windings or low-noise loads where discontinuous operation causes instability. |
| 99% duty cycle dropout operation | Dropout counter maintains bootstrap capacitor charge during near-100% duty cycles, enabling operation with VIN as low as VOUT + 0.3 V. |
| Logic-controlled micropower shutdown | IQ < 30 µA in shutdown with VRUN/SS = 0 V - extends runtime in battery-backed systems such as PDAs and wireless modems. |
Applications
| Notebook and Palmtop Computers | Cellular Telephones |
|---|---|
Use Scenario: Regulating core voltage (1.2 V) and I/O rail (3.3 V) in space-constrained mobile computing platforms with multi-cell Li-ion batteries (7–28 V). IC Role / Device Role / Timing Role: Primary synchronous buck controller managing high-current CPU/GPU power delivery with adaptive load-line response. Use Value: Eliminates sense resistor losses to achieve >90% efficiency at 4 A, while Burst Mode extends standby time beyond 72 hours on single-cell charge. | Use Scenario: Powering RF power amplifiers and baseband processors in GSM/UMTS handsets operating from 3.4–4.2 V battery packs. IC Role / Device Role / Timing Role: High-efficiency step-down controller delivering stable 2.8 V and 1.8 V rails with fast transient response to burst-mode transmission demands. Use Value: Achieves 92% peak efficiency at 1.5 A and maintains regulation during 200 mA load steps within 50 µs, minimizing RF interference from switching noise. |
| Battery Chargers | Distributed Power Systems |
Use Scenario: Generating isolated 5 V/3 A auxiliary supply in multi-chemistry smart chargers (Li-ion, NiMH) accepting 9–24 V DC input. IC Role / Device Role / Timing Role: Primary-side controller driving synchronous rectification in non-isolated buck stage feeding isolated flyback or forward converter. Use Value: Enables 94% efficiency at full load and <30 µA quiescent current in standby, meeting Energy Star Level VI requirements for no-load power. | Use Scenario: Local point-of-load regulation in telecom shelf systems where 48 V backplane supplies 3.3 V/10 A to FPGA and ASIC subsystems. IC Role / Device Role / Timing Role: High-current synchronous buck controller supporting parallel MOSFET configurations and external clock synchronization to avoid beat frequencies. Use Value: Delivers 93% efficiency at 10 A with <±0.5% output deviation across –40°C to +85°C, ensuring reliable operation in uncooled chassis environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3741EFE#PBF | Integrated high-side MOSFET (60 V, 4 A), fixed 200 kHz frequency, no VDS sensing - requires external sense resistor. | Targeted at higher input voltage (up to 60 V) and lower current (<4 A) applications; lacks programmable soft start and Burst Mode. | Select LT3741EFE#PBF only if integrated MOSFET simplifies layout and input exceeds 36 V; not suitable for no-RSENSE or ultra-low-IQ designs. |
| TPS54620RGYR | Integrated dual MOSFETs (30 V, 6 A), 350–550 kHz frequency, current-mode control with external sense resistor; IQ = 15 µA in Eco-mode. | Higher switching frequency enables smaller magnetics but increases gate loss; lacks VDS sensing and forced continuous mode pin. | Choose TPS54620RGYR for compact, high-density designs needing integrated FETs and wider VIN range (up to 30 V), but expect added sense resistor loss and no TK-based sensing. |
Compared with LT3741EFE#PBF and TPS54620RGYR, the LTC1625IS#PBF uniquely delivers true no-RSENSE operation, pin-selectable outputs, and dedicated FCB control for secondary regulation - making it optimal for cost-sensitive, high-efficiency portable and distributed power applications where external MOSFET flexibility and thermal management are critical.
Availability
LTC1625IS#PBF is available at Aetrix Electronics and suitable for notebook computers, cellular telephones, and battery charger designs requiring stable component supply, long-lifecycle support, and guaranteed industrial-grade (-40°C to +85°C) performance.
Supply support for LTC1625IS#PBF 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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC1625IS#PBF belongs to ADI's legacy Linear Technology power management portfolio, specifically designed for high-efficiency, synchronous step-down DC/DC conversion in portable, battery-powered, and distributed power systems where minimal external components and ultra-low quiescent current are essential.
FAQ
What is the operating temperature range for the LTC1625IS#PBF?
The LTC1625IS#PBF is rated for industrial temperature operation from –40°C to +85°C. This is confirmed in the Absolute Maximum Ratings table, where the "LTC1625I" grade (denoted by the 'I' suffix in the part number) specifies this range. The 'S' in LTC1625IS#PBF indicates the narrow SSOP package, and the '#PBF' denotes lead-free RoHS-compliant finish. The device maintains full electrical specifications across this range.
Does the LTC1625IS#PBF require an external current-sense resistor?
No, the LTC1625IS#PBF does not require an external current-sense resistor. It uses MOSFET VDS sensing via the TK (Kelvin sense) pin connected directly to the drain of the top N-channel MOSFET. This architecture eliminates sense resistor power loss and PCB area, and is explicitly stated in the product description as "No RSENSE" and "Current mode control with MOSFET VDS sensing eliminates the need for a sense resistor."
How is the output voltage programmed on the LTC1625IS#PBF?
The LTC1625IS#PBF supports three output voltage configurations via the VPROG pin: open-circuit for adjustable output using an external resistor divider on VOSENSE; 0 V for fixed 3.3 V output; or INTVCC (≈5.2 V) for fixed 5 V output. These selections are validated in the Electrical Characteristics table under "VOUT Regulated Output Voltage," which lists min/typ/max values for each mode.
What protection features does the LTC1625IS#PBF include?
The LTC1625IS#PBF includes foldback current limiting (reducing peak current from 150 mV to 30 mV threshold during overload), output overvoltage lockout (1.24–1.32 V), logic-controlled micropower shutdown (IQ < 30 µA), and dropout recovery via internal counter. These are documented in the Features list, Absolute Maximum Ratings, and Applications Information sections of the datasheet.
Can the LTC1625IS#PBF be synchronized to an external clock?
Yes, the LTC1625IS#PBF can be synchronized to an external clock via the SYNC pin. It supports injection locking over a 1.5:1 frequency range (e.g., 100–225 kHz for a nominal 150 kHz oscillator), with a defined clock waveform requirement (high level >1.2 V for 1–4 µs). This is specified in the Features list ("Programmable Fixed Frequency with Injection Lock") and detailed in the Electrical Characteristics table under fH/fOSC and VSYNC parameters.
LTC1625IS#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Boost
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 3.9V ~ 36V
- Frequency - Switching:
- 150kHz
- Duty Cycle (Max):
- 99%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
LTC1625IS#PBF FAQ
1.How can I place an order for LTC1625IS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1625IS#PBF 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 LTC1625IS#PBF reliable?
The price and inventory of LTC1625IS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1625IS#PBF is usually 5 days.
3.What payment methods are accepted for LTC1625IS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1625IS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1625IS#PBF?
LTC1625IS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1625IS#PBF 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 LTC1625IS#PBF?
For technical support, including LTC1625IS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1625IS#PBF requirements.
6.How does Aetrix verify that LTC1625IS#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1625IS#PBF 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 LTC1625IS#PBF meets industry standards.
7.What is the process for return or replacement of LTC1625IS#PBF?
All LTC1625IS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1625IS#PBF, 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 LTC1625IS#PBF part is unused and in its original packaging.
Return procedure for LTC1625IS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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