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Analog Devices Inc. LT1575CN8#PBF
- Part No.:
- LT1575CN8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LT1575CN8#PBF.pdf
- Description:
- IC LNR REG CTRLR 1OUT 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:138
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Product details
Overview
LT1575CN8#PBF from Analog Devices (formerly Linear Technology) is an adjustable low-dropout linear regulator controller IC that drives external N-channel MOSFETs in source-follower configuration to deliver ultrafast transient response for microprocessor core supplies. It features 1.21 V reference accuracy (±0.6% at 25°C, ±1% over 0°C–70°C), 50 mV current limit threshold, and supports up to 5 A output with <100 ns load-step response - enabling elimination of bulk electrolytic/tantalum output capacitors in Pentium® and PowerPC™ applications.
For engineers reviewing the LT1575CN8#PBF datasheet, LT1575CN8#PBF pinout, LT1575CN8#PBF application, or LT1575CN8#PBF equivalent, key selection considerations include its 8-pin PDIP package, adjustable output via FB pin, high-side current sense architecture, shutdown latchoff timing control, and compatibility with ceramic-only output networks (e.g., 24 × 1 µF X7R).
Technical Context
The LT1575CN8#PBF implements a precision error amplifier with 15 mS transconductance and 84 dB open-loop DC gain, referenced to a trimmed 1.21 V bandgap. Its COMP pin provides direct access to the high-impedance gain node for RC compensation, enabling loop crossover frequencies up to ~1 MHz while maintaining stability.
It integrates multifunction protection: a high-side current limit amplifier (50 mV threshold) feeds a programmable SHDN timer; the SHDN pin serves as comparator input (1.21 V reference, 100 mV hysteresis), supporting latchoff, overvoltage, or thermal shutdown via external resistor dividers - all without requiring additional ICs or complex circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 1.210 V ±0.6% at 25°C; enables precise output setting via external divider on FB pin |
| Output Accuracy | ±1% over 0°C to 70°C ambient; ensures stable core voltage under thermal stress |
| Current Limit Threshold | 50 mV typical; sets overcurrent trip point using external sense resistor (e.g., 10 mΩ → 5 A limit) |
| GATE Drive Capability | 50 mA peak output; slews MOSFET gate fast enough to support sub-microsecond load transients |
| Supply Current (IQ) | 5–19 mA; low quiescent draw minimizes idle power loss in always-on CPU supply rails |
| Line Regulation | 0.01–0.03 %/V; maintains tight output stability across 10–20 V input range |
| Operating Temp Range | 0°C to 70°C ambient; validated for commercial motherboard environments |
Pinout & Package
LT1575CN8#PBF is housed in an 8-lead plastic DIP (N8) package with 0.300-inch wide body and through-hole mounting. Thermal resistance θJA = 100°C/W. Pin 1 is SHDN; pin 3 is GND (analog ground and reference return); pin 4 is FB (adjustable version feedback input); pin 6 is GATE (MOSFET driver output).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SHDN (1) | Multifunction shutdown input | Comparator input (1.21 V ref, 100 mV hysteresis); controls latchoff timer, overvoltage, or thermal shutdown |
| VIN (2) | Main IC supply input | Powers internal circuitry and provides gate drive compliance; max 22 V absolute rating |
| GND (3) | Analog ground / reference return | Return path for 1.21 V reference and FB divider; must be star-connected to minimize noise coupling |
| FB (4) | Error amplifier inverting input | Connects to resistor divider from output; sets regulated voltage as VOUT = 1.21 × (1 + R1/R2) |
| COMP (5) | Error amplifier high-Z gain node | External RC compensation point; determines loop stability and bandwidth (typ. 1 MHz crossover) |
| GATE (6) | MOSFET gate driver output | Drives N-channel MOSFET source follower; delivers 50 mA peak for fast transient recovery |
| INEG (7) | Current limit amplifier negative sense | Connects to low-side of sense resistor; enables high-side current monitoring without affecting main loop |
| IPOS (8) | Current limit amplifier positive sense | Tied to input rail; also enables differential voltage monitoring for safe startup under slow-ramp conditions |
Key Features
| Feature | Design Value |
|---|---|
| Ultrafast transient response | Eliminates need for bulk electrolytic/tantalum output capacitors - only 24 × 1 µF ceramics required for Pentium® loads |
| FET RDS(ON)-defined dropout | Dropout voltage set solely by external MOSFET's on-resistance; enables sub-100 mV dropout at 5 A with suitable FET |
| 1% output tolerance over temperature | Ensures reliable microprocessor core voltage compliance across full operating range without derating |
| High-side sense current limit | Active protection with 50 mV threshold; avoids gain variation issues inherent in PNP-based solutions |
| Multifunction SHDN pin | Single pin supports latchoff timeout, overvoltage, and thermal shutdown - reduces BOM count and board space |
Applications
| Pentium® Processor Core Supply | PowerPC™ I/O Supply |
|---|---|
|
Use Scenario: Regulating 3.3 V core voltage for Intel Pentium® processors during rapid 0.2 A → 5 A load steps. IC Role / Device Role / Timing Role: Adjustable LDO controller driving IRFZ24 N-MOSFET; provides sub-100 ns transient recovery via 1 MHz loop bandwidth. Use Value: Enables use of only 24 × 1 µF ceramic capacitors instead of bulky electrolytics - saving >30% board area and eliminating ESR-related instability. |
Use Scenario: Generating stable 2.8 V or 3.3 V I/O supply for IBM PowerPC™ systems with tight ±100 mV transient tolerance. IC Role / Device Role / Timing Role: Fixed-output variant controller (e.g., LT1575CN8-2.8) managing high di/dt I/O switching noise. Use Value: Maintains 1% output accuracy over 0°C–70°C while rejecting input ripple - critical for signal integrity in high-speed bus interfaces. |
| GTL Bus Termination | Low-Voltage Logic (LVL) Supply |
|
Use Scenario: Providing dynamically adjustable 1.2 V termination voltage for GTL+ buses in server memory controllers. IC Role / Device Role / Timing Role: Adjustable controller (LT1575CN8) with remote sensing via FB pin; compensates for PCB trace IR drop. Use Value: Delivers <1 mV load regulation (typ.) - ensures consistent bus voltage across varying channel loading and temperature. |
Use Scenario: Powering 1.5 V or 1.8 V logic families (e.g., LVCMOS) in FPGA I/O banks requiring clean, low-noise bias. IC Role / Device Role / Timing Role: Fixed-output controller (e.g., LT1575CN8-1.5) with ceramic-only output filtering and 50 mV current limit. Use Value: Achieves <10 µV RMS output noise (typ.) - prevents timing jitter in high-speed clock distribution networks. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LDO controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1702AIS8#PBF | Switching controller (synchronous buck), not linear; higher efficiency but requires inductor and more complex layout | Used where >85% efficiency at 5 A is mandatory; unsuitable for ultra-low-noise analog rails | Select when thermal limits or battery life constrain linear solution; avoid for noise-sensitive PLL supplies |
| LT1585CT-3.3#PBF | Monolithic 3.3 V fixed LDO (3 A), no external MOSFET; lower integration but no gate drive or current sense flexibility | Suitable for simpler, lower-current applications (<3 A) where board space permits TO-220 package | Choose for cost-sensitive designs with modest transient demands; cannot match LT1575CN8#PBF's 5 A capability or ceramic-only operation |
Compared with LTC1702AIS8#PBF and LT1585CT-3.3#PBF, the LT1575CN8#PBF uniquely balances ultrafast transient response, external MOSFET flexibility, and ceramic-only output requirements - making it optimal for high-performance microprocessor core supplies where noise, size, and dynamic regulation are prioritized over raw efficiency.
Availability
LT1575CN8#PBF is available at Aetrix Electronics and suitable for Pentium® processor core supplies, PowerPC™ I/O rails, GTL bus termination, and low-voltage logic supplies requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT1575CN8#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 acquired Linear Technology in 2017 and maintains full technical and manufacturing continuity for legacy Linear products including the LT1575 family.
The LT1575 series was designed specifically for ultrafast transient-response microprocessor core regulators, targeting elimination of bulk output capacitance while delivering ±1% accuracy and robust protection in commercial-grade motherboards.
FAQ
What is the primary function of the LT1575CN8#PBF in a power supply design?
The LT1575CN8#PBF is an adjustable low-dropout linear regulator controller IC that drives external N-channel MOSFETs to regulate output voltage with ultrafast transient response. Unlike monolithic LDOs, it offloads power handling to the MOSFET while retaining precision control - enabling ceramic-only output filtering and sub-microsecond load-step recovery in LT1575CN8#PBF-based designs.
Can the LT1575CN8#PBF be used with fixed-output voltages like 3.3 V or 1.5 V?
No - the LT1575CN8#PBF is the adjustable version and requires an external resistor divider on the FB pin to set output voltage. Fixed-output variants exist (e.g., LT1575CN8-3.3#PBF), but LT1575CN8#PBF itself must be configured externally. Its FB pin accepts feedback from any output voltage, making it flexible for custom values such as 1.25 V or 2.5 V in LT1575CN8#PBF implementations.
How does the SHDN pin on the LT1575CN8#PBF provide overvoltage protection?
The SHDN pin on the LT1575CN8#PBF functions as the positive input to an internal comparator referenced to the 1.21 V bandgap. When an external resistor divider raises SHDN above 1.21 V (with 100 mV hysteresis), the comparator latches the GATE output low, disabling the external MOSFET. This mechanism allows simple, accurate overvoltage protection without additional ICs in LT1575CN8#PBF circuits.
What is the role of the INEG and IPOS pins in the LT1575CN8#PBF current limit function?
The INEG and IPOS pins form the differential input of a high-side current sense amplifier in the LT1575CN8#PBF. A sense resistor placed between them develops a voltage proportional to load current; when this reaches 50 mV, the amplifier triggers current limit action. If unused, INEG can be tied to IPOS to disable sensing - preserving full functionality of the LT1575CN8#PBF in non-current-limited configurations.
Why does the LT1575CN8#PBF eliminate the need for bulk electrolytic capacitors?
The LT1575CN8#PBF achieves ~1 MHz loop bandwidth and ultrafast transient response (<100 ns), allowing it to correct large load steps before bulk capacitance would react. Its architecture supports stable operation with only high-frequency ceramic capacitors (e.g., 24 × 1 µF), eliminating ESR-dependent electrolytics. This reduces cost, size, and failure risk - a defining feature of every LT1575CN8#PBF application.
LT1575CN8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- Positive Adjustable
- Number of Outputs:
- 1
- Current - Supply:
- 12mA
- Voltage - Input:
- 10V ~ 20V
- Operating Temperature:
- 0°C ~ 70°C
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LT1575CN8#PBF FAQ
1.How can I place an order for LT1575CN8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1575CN8#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 LT1575CN8#PBF reliable?
The price and inventory of LT1575CN8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1575CN8#PBF is usually 5 days.
3.What payment methods are accepted for LT1575CN8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1575CN8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1575CN8#PBF?
LT1575CN8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1575CN8#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 LT1575CN8#PBF?
For technical support, including LT1575CN8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1575CN8#PBF requirements.
6.How does Aetrix verify that LT1575CN8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1575CN8#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 LT1575CN8#PBF meets industry standards.
7.What is the process for return or replacement of LT1575CN8#PBF?
All LT1575CN8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1575CN8#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 LT1575CN8#PBF part is unused and in its original packaging.
Return procedure for LT1575CN8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT1575CN8#PBF Tags
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LT1575CS8#PBF
Analog Devices Inc.
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RT9008GE
Richtek USA Inc.
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S-816A40AMC-BAPT2U
ABLIC Inc.
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MIC5156YM
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MIC5156-3.3YM
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MIC5158YM-TR
Microchip Technology
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MAX8564AEUB+
Analog Devices Inc./Maxim Integrated
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LT1573CS8#PBF
Analog Devices Inc.
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UC2834DW
Texas Instruments
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RT9194GE
Richtek USA Inc.
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S-816A33AMC-BAIT2U
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