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Analog Devices Inc. LTC1553CG#PBF
- Part No.:
- LTC1553CG#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1553CG#PBF.pdf
- Description:
- IC REG CTRLR INTEL 1OUT 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,500
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Product details
Overview
LTC1553CG#PBF from Analog Devices (formerly Linear Technology) is a 5-bit digitally programmable synchronous buck controller IC designed for Intel Pentium® II VRM 8.2-compliant CPU power supplies. It delivers 1.8V–3.5V output from 5V/12V input, supports 14A output current, features ±1.5% initial voltage accuracy and ±2% typical accuracy over line/load/temperature, and integrates dual N-channel MOSFET gate drivers with internal current-sense architecture using Q1's RDS(ON).
For engineers reviewing the LTC1553CG#PBF datasheet, LTC1553CG#PBF pinout, LTC1553CG#PBF application, or LTC1553CG#PBF equivalent, this page provides verified technical context, exact pin functions, confirmed VRM 8.2 compliance, real-world transient response data, and validated alternative controllers for Pentium II and compatible high-power microprocessor supply designs.
Technical Context
The LTC1553CG#PBF implements a voltage-mode synchronous buck controller with an internal 1.265V precision reference, 5-bit VID DAC, and dual gate drivers (G1/G2) optimized for high-efficiency, low-voltage regulation. Its feedback loop uses SENSE-pin sensing with internal 120kΩ divider and external RC+C compensation at COMP.
It incorporates three parallel protection loops: MIN/MAX comparators for ±5% fast over/under-voltage response (2–3 µs), a current-limit circuit sampling IFB vs IMAX before each G1 falling edge, and thermal shutdown triggered via OUTEN voltage thresholds (2.0V OT warning, 1.7V driver disable, 1.2V shutdown).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | 1.8V to 3.5V, digitally set via 5-bit VID0–VID4 per Intel VRM 8.2 table; disabled codes prevent invalid voltages. |
| Initial Accuracy | ±1.5% at room temperature - ensures immediate compliance with Pentium II VOUT tolerance at power-up. |
| Accuracy Over Conditions | ±2% typical over line (4.5–8V VCC), load (0–14A), and temperature (0°C–70°C) - guarantees stable core voltage under dynamic CPU loads. |
| Oscillator Frequency | 250–350 kHz (typ. 300 kHz); free-running or synchronizable via OUTEN - enables EMI control and inductor size optimization. |
| Output Current Capability | 14A continuous (19A peak) - supports full Pentium II processor power envelope with margin. |
| Power Good Window | ±5% of rated VOUT, with 1ms high-validity delay and 500µs fault detection - meets VRM 8.2 PWRGD timing requirements. |
| Fault Response Times | tPWRGD = 0.5–2 ms ↑, tFAULT = 200–1000 µs, tOT = 15–60 µs - enables rapid system-level fault isolation without software latency. |
Pinout & Package
The LTC1553CG#PBF is housed in a 20-lead plastic SSOP (G package) with 0.65 mm lead pitch and exposed pad for thermal dissipation. Pin numbering follows standard top-view layout with G1 (Pin 20) and G2 (Pin 1) as high-current gate drivers.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| G1 (Pin 20) | Upper N-MOSFET gate driver | Swings PVCC-to-GND; drives Q1; disabled when G2 is active or OUTEN=low - prevents shoot-through. |
| G2 (Pin 1) | Lower N-MOSFET gate driver | Swings PVCC-to-GND; always low when G1 is high - ensures complementary switching and dead-time control. |
| SENSE (Pin 6) | Output voltage feedback input | Connects to +VOUT; internal 120kΩ divider to SGND; requires 0.1µF bypass to SGND for noise immunity and loop stability. |
| IMAX (Pin 7) | Current limit threshold reference | 180µA internal sink sets trip point via external resistor to VIN; eliminates need for discrete sense resistor. |
| IFB (Pin 8) | Current sense input | Monitors switching node between Q1 drain and Q2 source; samples Q1 RDS(ON) drop - enables lossless current limiting. |
| VID0–VID4 (Pins 14–18) | Digital voltage identification inputs | TTL-compatible; internal 20kΩ pull-ups; define 1.8V–3.5V output per VRM 8.2 table; all-high = shutdown. |
| OUTEN (Pin 19) | Enable/thermal monitor input | Three-threshold function: >2V = normal, <2V = OT warning, <1.7V = driver disable, <1.2V = shutdown - supports thermistor-based thermal management. |
| PWRGD (Pin 13) | Open-drain power-good output | Asserts high only after VOUT settles within ±5% for ≥1ms; deasserts within 500µs if out-of-regulation - satisfies VRM 8.2 sequencing. |
Key Features
| Feature | Design Value |
|---|---|
| VRM 8.2 Compliance | Fully implements Intel Pentium II DC/DC specification including VID coding, PWRGD timing, and fault signaling - eliminates validation risk in x86 platforms. |
| RDS(ON)-Based Current Limit | Uses upper FET's on-resistance as current sensor - removes 5–10 mΩ sense resistor, reducing BOM cost, PCB area, and power loss in high-current path. |
| Dual Fast Protection Loops | MIN/MAX comparators respond in 2–3 µs to ±5% VOUT excursions - protects CPU from transient overvoltage/undervoltage faster than main error amplifier loop. |
| Thermal Monitoring via OUTEN | Three internal voltage thresholds on single pin enable direct NTC thermistor interface - simplifies thermal design without external ADC or comparator. |
| Synchronous Gate Drive | G1/G2 drivers support 14A+ output with 90–150 ns rise/fall times and 30–100 ns nonoverlap - maximizes efficiency by minimizing conduction and switching losses. |
Applications
| Intel Pentium II CPU Power Supply | SPARC/Alpha PA-RISC Core Regulator |
|---|---|
|
Use Scenario: Primary core voltage regulator for desktop/server Pentium II processors requiring strict VRM 8.2 compliance and fast transient response. IC Role / Device Role / Timing Role: Synchronous buck controller managing 5V/12V-to-1.8V–3.5V conversion with VID-programmable output and integrated fault signaling. Use Value: Delivers ±2% output accuracy across 0–14A load steps and 0°C–70°C ambient, meeting Intel's tight core voltage tolerance for stable CPU operation. |
Use Scenario: High-current, low-voltage supply for SPARC, Alpha, and PA-RISC microprocessors with similar VRM-like voltage programming needs. IC Role / Device Role / Timing Role: Programmable synchronous controller supporting multi-voltage rail sequencing and fast PWRGD assertion for RISC CPU boot integrity. Use Value: Leverages same 5-bit VID interface and ±5% PWRGD window used in Pentium II systems - enables reuse of firmware and layout across architectures. |
| High-Efficiency 12V-to-2.8V Server PSU | Industrial Embedded Microprocessor Supply |
|
Use Scenario: 12V input, 2.8V/14A output supply in dense server power modules where thermal management and efficiency are critical. IC Role / Device Role / Timing Role: Controller with PVCC charge-pump support (for 12V input), dual gate drive, and OT-triggered driver disable to prevent MOSFET thermal runaway. Use Value: Achieves >95% efficiency at full load (per typical curves) and shuts down drivers at 1.7V OUTEN - protects power stage during sustained overload. |
Use Scenario: Reliable, long-lifecycle power supply for industrial embedded systems using legacy x86 or RISC CPUs requiring stable low-voltage rails. IC Role / Device Role / Timing Role: Robust controller with shutdown supply current of 130–250 µA and guaranteed operation from 0°C to 70°C - supports extended-temperature deployments. Use Value: Maintains ±2% regulation across wide input (4.5–8V VCC) and load (0–14A), ensuring consistent performance in variable industrial 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 |
|---|---|---|---|
| ISL6522CRZ | 6-bit VID, 0.8V–2.0V range, integrated MOSFET drivers, 300kHz fixed frequency - lacks RDS(ON) current sensing and OUTEN thermal thresholds. | Targeted at later Pentium III/4 VRM specs; narrower voltage range excludes 2.8V–3.5V use cases supported by LTC1553CG#PBF. | Select ISL6522CRZ only for newer VRM 8.4/8.5 designs requiring sub-2V outputs; not drop-in for Pentium II 2.8V+ configurations. |
| TPS51116PWR | Single-chip solution with integrated 30V/30A MOSFETs, 5-bit VID, 300kHz frequency - no external gate drive flexibility or RDS(ON) current limit option. | Designed for space-constrained notebooks; lacks separate PVCC/G1/G2 pins and thermistor-ready OUTEN logic. | Choose TPS51116PWR for compact, low-component-count designs; LTC1553CG#PBF remains preferred for high-reliability, thermally monitored server PSUs. |
Compared with ISL6522CRZ and TPS51116PWR, the LTC1553CG#PBF uniquely combines VRM 8.2 compliance, 1.8V–3.5V programmability, RDS(ON)-based current limiting, and triple-threshold thermal monitoring on OUTEN - making it irreplaceable for legacy Pentium II and compatible high-power, thermally demanding applications.
Availability
LTC1553CG#PBF is available at Aetrix Electronics and suitable for Intel Pentium II CPU power supplies, SPARC/Alpha core regulators, and industrial embedded microprocessor supplies requiring stable component supply, long-term lifecycle support, and VRM 8.2 compliance.
Supply support for LTC1553CG#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving aerospace, industrial, communications, and computing markets.
The LTC1553CG#PBF belongs to Linear's legacy high-efficiency power controller family, specifically engineered for Intel VRM-compliant CPU core supplies - emphasizing precision voltage regulation, fast transient response, and robust fault protection in high-current buck topologies.
FAQ
What is the operating temperature range for the LTC1553CG#PBF?
The LTC1553CG#PBF is specified for an operating temperature range of 0°C to 70°C, matching the commercial-grade requirement for desktop Pentium II platforms. Its over-temperature protection triggers at 1.9–2.12V on the OT pin when OUTEN drops below 2V, and full shutdown occurs below 1.2V - providing layered thermal safety within this ambient range.
Does the LTC1553CG#PBF require an external current sense resistor?
No, the LTC1553CG#PBF does not require an external current sense resistor. It implements lossless current limiting by sensing the voltage drop across the RDS(ON) of the upper N-channel MOSFET (Q1) via the IFB pin, referenced against the IMAX pin voltage set by an external resistor - eliminating BOM cost and PCB footprint while maintaining fault protection.
How is the output voltage programmed on the LTC1553CG#PBF?
The LTC1553CG#PBF uses a 5-bit digital VID interface (VID0–VID4) to program output voltage from 1.8V to 3.5V in 50mV steps, per Intel VRM 8.2 Table 3. Each pin is TTL-compatible with internal 20kΩ pull-up resistors; all five pins high or floating forces shutdown - ensuring safe default behavior during configuration errors.
What package type is used for the LTC1553CG#PBF?
The LTC1553CG#PBF is packaged in a 20-lead plastic SSOP (Small Outline Package) with gull-wing leads and 0.65 mm pitch, designated as the "G" package by Linear Technology. This surface-mount package supports automated assembly and provides adequate thermal dissipation for its 14A output capability when mounted on appropriate copper area.
Can the LTC1553CG#PBF be synchronized to an external clock?
Yes, the LTC1553CG#PBF can be synchronized to an external clock signal applied to the OUTEN pin. Its internal oscillator operates at 300 kHz (250–350 kHz range), and connecting a faster external clock to OUTEN overrides the free-running frequency - enabling EMI reduction and precise timing alignment in multi-rail power systems.
LTC1553CG#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Controller, Intel Pentium® II
- Voltage - Input:
- 5V, 12V
- Number of Outputs:
- 1
- Voltage - Output:
- 1.8V ~ 3.5V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
LTC1553CG#PBF FAQ
1.How can I place an order for LTC1553CG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1553CG#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 LTC1553CG#PBF reliable?
The price and inventory of LTC1553CG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1553CG#PBF is usually 5 days.
3.What payment methods are accepted for LTC1553CG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1553CG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1553CG#PBF?
LTC1553CG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1553CG#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 LTC1553CG#PBF?
For technical support, including LTC1553CG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1553CG#PBF requirements.
6.How does Aetrix verify that LTC1553CG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1553CG#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 LTC1553CG#PBF meets industry standards.
7.What is the process for return or replacement of LTC1553CG#PBF?
All LTC1553CG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1553CG#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 LTC1553CG#PBF part is unused and in its original packaging.
Return procedure for LTC1553CG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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