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Analog Devices Inc. LT1959CS8#TRPBF
- Part No.:
- LT1959CS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1959CS8#TRPBF.pdf
- Description:
- IC REG BUCK SEPIC ADJ 4.5A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,743
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Product details
Overview
LT1959CS8#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic 500 kHz current-mode buck switching regulator with an integrated 4.5 A NPN power switch, 1.21 V feedback reference, and BOOST pin for switch saturation. It operates from 4.0 V minimum input and delivers adjustable output down to 1.21 V, optimized for portable computers and battery-powered systems requiring high efficiency at light-to-full load.
For engineers reviewing the LT1959CS8#TRPBF datasheet, LT1959CS8#TRPBF pinout, LT1959CS8#TRPBF application, or LT1959CS8#TRPBF equivalent, key selection considerations include its 0.07 Ω typical switch on-resistance, cycle-by-cycle current limiting, shutdown current of 15 µA, synchronization capability up to 1 MHz, and SO-8 package compatibility with fused-ground thermal design.
Technical Context
The LT1959CS8#TRPBF implements constant-frequency current-mode control using an internal 500 kHz oscillator, error amplifier (2000 µ℧ transconductance), and peak-current comparator referenced to the VC pin. Its bipolar NPN switch is driven via the BOOST pin to achieve saturation-reducing conduction loss versus standard bipolar designs.
Protection features include full cycle-by-cycle short-circuit limiting, thermal shutdown, undervoltage lockout (2.38 V), and dual-threshold shutdown (0.4 V full micropower mode). Frequency foldback below 0.5 V FB voltage and current limit foldback below 0.8 V FB voltage enhance robustness during output short-circuit conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Rating | 4.5 A at ≤50% duty cycle; enables ≥3.7 A continuous output with 5 V → 3.3 V conversion using 10 µH inductor |
| Feedback Reference Voltage | 1.21 V (±20 mV over temp); sets output voltage via external resistor divider with <0.1% error at R2 ≤ 2.5 kΩ |
| Switch On Resistance | 0.07 Ω typical (at 4.5 A); reduces conduction loss and improves efficiency vs. non-boosted bipolar switches |
| Minimum Input Voltage | 4.0 V (guaranteed); supports operation from single-cell Li-ion or 5 V rail with margin |
| Shutdown Supply Current | 15 µA typical; enables ultra-low-power standby in battery systems without external disconnect |
| Synchronization Range | 580 kHz to 1 MHz; allows EMI reduction or multi-regulator phase alignment via external logic-level SYNC signal |
| Operating Junction Temp | 0°C to 125°C (C-grade); validated for industrial and portable computing environments with θJA = 30°C/W on 0.5 in² copper |
Pinout & Package
LT1959CS8#TRPBF is housed in an 8-lead plastic SO (SO-8) package with fused ground pin (Pin 4) thermally connected to the internal tab. The package supports standard surface-mount reflow and requires direct attachment to a large copper area for thermal management.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Input supply and collector of internal NPN switch | Must be bypassed near-pin with low-ESR capacitor; high dI/dt edges require short trace to GND and catch diode |
| BOOST (Pin 2) | Boost drive voltage source for NPN switch saturation | Requires external capacitor + diode to generate VIN + 5 V; enables 0.07 Ω effective RCE(sat) |
| GND (Pin 4) | Power and signal reference ground | Fused ground pin; must connect directly to PCB ground plane to minimize load regulation error and EMI |
| VSW (Pin 5) | Emitter of internal NPN switch | Drives inductor; clamped to –0.8 V max by external catch diode; high dv/dt node requiring tight layout |
| SYNC (Pin 6) | External oscillator synchronization input | Logic-compatible (10–90% duty cycle); unused must be grounded; enables frequency alignment up to 1 MHz |
| SHDN (Pin 7) | Shutdown control with dual thresholds | 2.38 V = UVLO disable; 0.4 V = full micropower shutdown; reduces supply current to 15 µA |
| VC (Pin 8) | Error amplifier output / current limit setpoint | Used for loop compensation; also serves as current clamp point; swings 1 V (light load) to 2 V (full load) |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode control architecture | Enables fast transient response and stable loop compensation without external slope compensation |
| BOOST-driven saturated NPN switch | Achieves >89% efficiency at 4 A (5 V → 3.3 V), outperforming conventional bipolar regulators (~75%) |
| Integrated cycle-by-cycle current limiting | Prevents switch damage during overload; limits peak current to 4.5 A (typical) with foldback below 0.8 V FB |
| Frequency foldback under fault | Reduces switching frequency ~5:1 when FB < 0.5 V, lowering power dissipation in IC and external components during short-circuit |
| Thermal shutdown + fused-GND SO-8 | Protects against sustained overtemperature; fused ground improves thermal resistance (θJA = 30°C/W on 0.5 in² copper) |
Applications
| Portable Computers | Battery-Powered Systems |
|---|---|
Use Scenario: Point-of-load regulation from 5 V main rail to 3.3 V or 2.5 V core logic in ultraportable notebooks. IC Role / Device Role / Timing Role: Primary buck converter delivering up to 4 A with tight output regulation and low quiescent current. Use Value: Enables extended battery life via 15 µA shutdown current and >89% efficiency across 10 mA–4 A load range. |
Use Scenario: Powering microcontrollers, sensors, and RF modules from single-cell Li-ion (3.0–4.2 V) or 3.3 V backup rails. IC Role / Device Role / Timing Role: Adjustable-output buck regulator supporting 1.21 V to 5 V outputs with input down to 4.0 V. Use Value: Maintains regulation through battery discharge curve without external LDO post-regulation. |
| Battery Chargers | Distributed Power |
Use Scenario: Charging circuit auxiliary supply for charge-management ICs and status LEDs in USB-C PD adapters. IC Role / Device Role / Timing Role: Secondary buck stage converting 9–15 V adapter output to 3.3 V system rail. Use Value: Sustains operation during high-voltage input transients while providing cycle-by-cycle current limiting for fault containment. |
Use Scenario: Local DC-DC conversion in telecom line cards or industrial I/O modules where 5 V or 12 V backplane supplies feed multiple 3.3 V/2.5 V loads. IC Role / Device Role / Timing Role: Compact, thermally robust buck regulator with SYNC pin for synchronized switching across multiple rails. Use Value: Reduces conducted EMI via synchronized 500 kHz operation and eliminates need for external current-sense resistors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3866EMSE#PBF | 40 V input, 10 A external MOSFET controller; no integrated switch; requires external gate drivers and FETs | Higher input voltage and current capability; suited for 12 V/24 V industrial inputs, not direct replacement | Select LTC3866EMSE#PBF only when >15 V input or >4.5 A output is required and board space permits discrete FET layout. |
| TPS544B20RHLT | 4.5–18 V input, 4 A integrated buck; 1.2 V reference; uses CMOS FETs; no BOOST pin; 500 kHz fixed frequency | Lower IQ (25 µA shutdown), smaller QFN package; lacks frequency foldback and dual-threshold shutdown | Choose TPS544B20RHLT for space-constrained consumer designs where robust short-circuit protection is secondary to footprint size. |
Compared with LTC3866EMSE#PBF and TPS544B20RHLT, the LT1959CS8#TRPBF uniquely combines integrated 4.5 A bipolar switch with BOOST-assisted saturation, dual-threshold shutdown, and frequency foldback-making it optimal for ruggedized 5 V-input portable and industrial buck applications where thermal performance and fault resilience are critical.
Availability
LT1959CS8#TRPBF is available at Aetrix Electronics and suitable for portable computers, battery-powered systems, and distributed power applications requiring stable component supply, long-term lifecycle support, and guaranteed authenticity.
Supply support for LT1959CS8#TRPBF 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 legacy Linear power products.
The LT1959CS8#TRPBF belongs to Linear's high-efficiency monolithic buck regulator family, designed specifically for compact, thermally demanding applications where integrated switch performance and robust fault handling outweigh controller+MOSFET flexibility.
FAQ
What is the minimum input voltage supported by the LT1959CS8#TRPBF?
The LT1959CS8#TRPBF guarantees operation down to 4.0 V input across temperature. This is defined by internal bias regulation stability-not absolute dropout-and actual minimum usable input depends on output voltage and load. For example, at 3.3 V output and 4 A load, VIN must exceed ~4.3 V to maintain regulation per typical performance curves. The LT1959CS8#TRPBF achieves this with its BOOST-assisted switch saturation, enabling reliable start-up from single-cell Li-ion sources.
How does the BOOST pin function in the LT1959CS8#TRPBF?
The BOOST pin on the LT1959CS8#TRPBF provides a drive voltage higher than VIN to saturate the internal NPN power switch, reducing effective on-resistance to 0.07 Ω. It requires an external capacitor and Schottky diode (e.g., MBRS330T3) connected between VIN and BOOST. Without BOOST, switch conduction loss would rise significantly-dropping efficiency from >89% to ~75%. The LT1959CS8#TRPBF's BOOST circuit draws 90–140 mA at 4.5 A switch current, enabling high efficiency without external MOSFETs.
Does the LT1959CS8#TRPBF support synchronization, and what is its range?
Yes, the LT1959CS8#TRPBF supports external synchronization via the SYNC pin (Pin 6), which accepts logic-level signals with 10–90% duty cycle. Its synchronizing range extends from the nominal 500 kHz up to 1 MHz. When unsynchronized, the oscillator operates at 460–540 kHz (typical 500 kHz). The LT1959CS8#TRPBF requires SYNC to be grounded when unused. This feature enables EMI reduction and multi-rail phase alignment in dense PCB layouts.
What protection features are built into the LT1959CS8#TRPBF?
The LT1959CS8#TRPBF integrates cycle-by-cycle current limiting, thermal shutdown, undervoltage lockout (2.38 V), and dual-threshold shutdown (0.4 V full micropower mode). It also implements frequency foldback (down to ~100 kHz) and current limit foldback when FB voltage drops below 0.5 V and 0.8 V respectively-critical for safe operation during output short-circuit. These protections are fully internal; no external components are needed. The LT1959CS8#TRPBF's fused-ground SO-8 package further enhances thermal reliability.
Can the LT1959CS8#TRPBF be used for 5 V to 1.8 V conversion, and what inductor value is recommended?
Yes, the LT1959CS8#TRPBF is explicitly rated for 5 V to 1.8 V conversion, as confirmed in its Applications section and Typical Application schematic (TA01). For 4 A output, a 1.8 µH inductor is recommended to minimize size while maintaining continuous conduction mode. The LT1959CS8#TRPBF's current-mode control ensures stability with this low inductance, and its BOOST pin sustains efficiency despite the high duty cycle (~36%). Inductor selection must respect peak current rating: IPEAK ≈ IOUT + (VOUT × (VIN − VOUT)) / (2 × f × L × VIN).
LT1959CS8#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck, SEPIC
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.3V
- Voltage - Input (Max):
- 15V
- Voltage - Output (Min/Fixed):
- 1.21V
- Voltage - Output (Max):
- 12.9V
- Current - Output:
- 4.5A (Switch)
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1959CS8#TRPBF FAQ
1.How can I place an order for LT1959CS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1959CS8#TRPBF 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 LT1959CS8#TRPBF reliable?
The price and inventory of LT1959CS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1959CS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1959CS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1959CS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1959CS8#TRPBF?
LT1959CS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1959CS8#TRPBF 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 LT1959CS8#TRPBF?
For technical support, including LT1959CS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1959CS8#TRPBF requirements.
6.How does Aetrix verify that LT1959CS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1959CS8#TRPBF 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 LT1959CS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1959CS8#TRPBF?
All LT1959CS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1959CS8#TRPBF, 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 LT1959CS8#TRPBF part is unused and in its original packaging.
Return procedure for LT1959CS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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