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Analog Devices Inc. LTC1553CG#TRPBF
- Part No.:
- LTC1553CG#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1553CG#TRPBF.pdf
- Description:
- IC REG CTRLR INTEL 1OUT 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,194
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Product details
Overview
LTC1553CG#TRPBF from Analog Devices (formerly Linear Technology) is a 5-bit digitally programmable synchronous buck controller optimized for Pentium® II VRM 8.2 compliant CPU power supplies. It delivers 1.8V–3.5V output from 5V/12V input, supports 19A peak 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 via Q1 RDS(ON).
For engineers reviewing the LTC1553CG#TRPBF datasheet, LTC1553CG#TRPBF pinout, LTC1553CG#TRPBF application, or LTC1553CG#TRPBF equivalent, key selection considerations include VRM 8.2 compliance, VID0–VID4 programmability, IMAX/IFB current-limit architecture, soft-start timing control via external capacitor, and thermal shutdown thresholds tied to OUTEN voltage levels.
Technical Context
The LTC1553CG#TRPBF implements a voltage-mode PWM control architecture with an internal 1.265V precision reference, 5-bit DAC-based VID interface, and dual high-current gate drivers (G1/G2) supporting synchronous rectification. Its feedback loop uses SENSE pin sensing with internal 120kΩ divider and COMP-pin compensation for stability across wide load transients.
It embeds three fast-acting protection comparators: MIN/MAX (±5% output window), FAULT (15% OV), and OT (over-temperature triggered by OUTEN voltage drop). Current limiting operates by sampling IFB against IMAX during G1 off-time, eliminating external sense resistors while enabling adjustable trip points via RIMAX.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | 1.8V to 3.5V, digitally set via VID0–VID4 per Intel VRM 8.2 table; disabled codes prevent invalid voltages. |
| Initial Accuracy | ±1.5% at room temperature - ensures immediate compliance with processor VCC tolerance at power-on. |
| Line/Load/Temp Accuracy | ±2% typical - maintains regulation under full operating conditions without recalibration. |
| Max Output Current | 19A peak - supports high-power Pentium II loads with margin for transient spikes. |
| Oscillator Frequency | 250–350kHz internal, free-running at 300kHz - sets switching node frequency for inductor/capacitor sizing. |
| Power Good Window | ±5% of rated output for ≥1ms high, >500µs low - provides reliable sequencing signal for CPU reset logic. |
| Overvoltage Trip | 12–20% above nominal - disables G1/G2 permanently until power cycle or OUTEN toggle. |
Pinout & Package
Package: 20-lead plastic SSOP (G package), 0.65mm pitch, RoHS-compliant, moisture sensitivity level 3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| G2 (Pin 1) | Lower N-MOSFET gate driver | Swings PVCC-to-GND; held low during soft start; synchronized with G1 nonoverlap timing. |
| PVCC (Pin 2) | High-side driver supply | Must exceed VIN + VGS(ON) of Q1; supports charge-pump or auxiliary 12V source. |
| GND (Pin 3) | Power ground | Low-impedance return for Q2 source; must connect near Q2 source to minimize noise coupling. |
| SGND (Pin 4) | Signal ground | Reference for internal analog circuitry; shorted to GND at device pin to avoid ground loops. |
| VCC (Pin 5) | Logic supply | 5V supply for internal logic; requires 10µF bypass to SGND; separate from Q1 drain routing. |
| SENSE (Pin 6) | Output voltage feedback | Connects to +COUT; internal 120kΩ divider to SGND; sensitive node requiring 0.1µF local bypass. |
| IMAX (Pin 7) | Current limit threshold | 180µA internal sink; sets trip point via external resistor to VIN; enables RDS(ON)-based sensing. |
| IFB (Pin 8) | Current sense input | Connects to Q1 source–Q2 drain node; samples RDS(ON) voltage drop during G1 off-time. |
| SS (Pin 9) | Soft start control | External capacitor sets ramp time; discharged during overload to reduce duty cycle gradually or instantly. |
| COMP (Pin 10) | Error amplifier output | Direct connection to PWM comparator; RC+C network here sets loop bandwidth and phase margin. |
| OT (Pin 11) | Over-temperature flag | Open-drain; pulled low when OUTEN < 2V - signals thermal warning to system controller. |
| FAULT (Pin 12) | Overvoltage fault | Open-drain; latched low on 15% OV event; requires power recycle or OUTEN toggle to clear. |
| PWRGD (Pin 13) | Power good indicator | Open-drain; high only when output remains within ±5% for ≥1ms - used for CPU enable sequencing. |
| VID0–VID4 (Pins 14–18) | Digital voltage select | TTL inputs with 20kΩ internal pull-up; define 1.8V–3.5V in 50mV steps per VRM 8.2 table. |
| OUTEN (Pin 19) | Enable/thermal input | TTL enable with three thresholds: >2V normal, <2V OT warning, <1.7V driver disable, <1.2V shutdown. |
| G1 (Pin 20) | Upper N-MOSFET gate driver | Swings PVCC-to-GND; drives Q1 gate; disabled when G2 is active to prevent shoot-through. |
Key Features
| Feature | Design Value |
|---|---|
| 5-bit VID interface | Enables precise, processor-directed voltage scaling per Intel VRM 8.2 without external DAC or firmware. |
| RDS(ON) current sensing | Eliminates discrete current-sense resistor, reducing BOM count, PCB area, and power loss in high-current path. |
| Triple-threshold OUTEN | Supports integrated thermal monitoring using single NTC thermistor - no extra ADC or comparator required. |
| MIN/MAX fast comparators | Provides ±5% output window protection with 2–3µs response - prevents catastrophic overshoot/undershoot during transients. |
| Synchronous dual gate drivers | Drives both high- and low-side N-MOSFETs directly, enabling >95% efficiency and removing need for P-channel high-side switch. |
Applications
| Desktop CPU Power Supply | Workstation VRM Module |
|---|---|
Use Scenario: Primary 1.8V–3.5V core supply for Intel Pentium II microprocessors in desktop motherboards. IC Role / Device Role / Timing Role: VRM 8.2-compliant synchronous buck controller managing VID decoding, PWM generation, and dual-MOSFET drive. Use Value: Delivers ±2% regulation accuracy and 19A peak current while meeting Intel's strict transient response and sequencing requirements. | Use Scenario: High-reliability 2.8V/3.3V supply for SPARC/Alpha/PA-RISC processors in engineering workstations. IC Role / Device Role / Timing Role: Programmable step-down controller with integrated fault flags (PWRGD, FAULT, OT) for system-level monitoring. Use Value: Enables single-chip implementation of multi-rail CPU power with thermal warning, overvoltage lockout, and soft-start sequencing. |
| Industrial Embedded CPU Board | Legacy Server Power Management |
Use Scenario: Compact 5V-input-to-2.5V core regulator on space-constrained embedded boards running Pentium II derivatives. IC Role / Device Role / Timing Role: Synchronous controller with SS pin-based soft-start and IMAX-adjustable current limit for robust startup. Use Value: Reduces component count vs. discrete solutions and avoids external sense resistor heating in sealed enclosures. | Use Scenario: Replacement VRM controller in aging server platforms requiring long-term availability and documented VRM 8.2 support. IC Role / Device Role / Timing Role: Pin-compatible upgrade path from earlier Linear controllers (e.g., LTC1336) with enhanced accuracy and thermal management. Use Value: Maintains legacy board compatibility while improving output stability and adding overtemperature fault signaling. |
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-T | 6-bit VID, 300kHz fixed frequency, supports 3.3V/2.5V/1.8V VRM 8.5; no IMAX/IFB current sensing - uses external resistor. | Targeted at newer Pentium III systems; lacks RDS(ON) sensing and triple-threshold OUTEN. | Select if upgrading to VRM 8.5 compliance is required and external sense resistor is acceptable. |
| TPS51100PWR | 5-bit VID, 300kHz, integrated MOSFET drivers; uses external current-sense resistor; no dedicated OT pin - relies on thermal shutdown via junction temp. | Designed for mobile CPU power; lower quiescent current but no OUTEN-based thermistor interface. | Select for battery-powered or thermally constrained designs where integrated FET drivers simplify layout. |
Compared with ISL6522CRZ-T and TPS51100PWR, the LTC1553CG#TRPBF uniquely combines VRM 8.2 compliance, RDS(ON)-based current limiting, and a three-level OUTEN thermal interface - making it irreplaceable for legacy Pentium II systems requiring minimal BOM count and direct thermistor integration.
Availability
LTC1553CG#TRPBF is available at Aetrix Electronics and suitable for desktop motherboard design, workstation VRM modules, and industrial embedded CPU power supplies requiring stable component supply and long-lifecycle support.
Supply support for LTC1553CG#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 support for legacy Linear power management ICs including the LTC1553 family.
The LTC1553 product line was designed specifically to meet Intel's Pentium II VRM 8.2 specification, delivering high-efficiency, digitally programmable CPU core power with integrated protection and thermal monitoring.
FAQ
What is the supported output voltage range for the LTC1553CG#TRPBF?
The LTC1553CG#TRPBF supports a digitally programmable output voltage range from 1.8V to 3.5V in 50mV increments, as defined by the 5-bit VID0–VID4 input code per Intel VRM 8.2 specification. Codes outside this range disable the output or force shutdown - ensuring only valid processor voltages are generated by the LTC1553CG#TRPBF.
How does the LTC1553CG#TRPBF implement current limiting without an external sense resistor?
The LTC1553CG#TRPBF senses output current through the RDS(ON) of the upper N-channel MOSFET (Q1) using the IFB pin. During each G1 off-time, the current comparator samples the voltage drop across Q1 and compares it to the IMAX pin voltage. When IFB falls below IMAX, the soft-start capacitor is discharged to reduce duty cycle - enabling adjustable, resistorless current limiting in the LTC1553CG#TRPBF.
What are the three voltage thresholds on the OUTEN pin of the LTC1553CG#TRPBF?
The OUTEN pin of the LTC1553CG#TRPBF has three defined thresholds: >2V enables normal operation; <2V triggers OT (over-temperature warning); <1.7V disables G1/G2 drivers to halt switching; and <1.2V initiates full shutdown with ~130µA quiescent current. All transitions require >30µs hold time - providing noise immunity while enabling precise thermal monitoring via a single NTC thermistor in the LTC1553CG#TRPBF.
Does the LTC1553CG#TRPBF support external clock synchronization?
Yes, the LTC1553CG#TRPBF can synchronize its internal 300kHz oscillator to a faster external clock applied to the OUTEN pin. This allows designers to optimize switching frequency for EMI reduction or inductor/capacitor selection without modifying the LTC1553CG#TRPBF's internal timing architecture.
What package type is used for the LTC1553CG#TRPBF?
The LTC1553CG#TRPBF is packaged in a 20-lead plastic SSOP (Small Outline Package) with 0.65mm lead pitch, designated as the "G" package by Linear Technology. It is RoHS-compliant, moisture sensitivity level 3, and pin-compatible with other LTC1553 variants in the same package family.
LTC1553CG#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LTC1553CG#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1553CG#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 LTC1553CG#TRPBF reliable?
The price and inventory of LTC1553CG#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1553CG#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1553CG#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1553CG#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1553CG#TRPBF?
LTC1553CG#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1553CG#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 LTC1553CG#TRPBF?
For technical support, including LTC1553CG#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1553CG#TRPBF requirements.
6.How does Aetrix verify that LTC1553CG#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1553CG#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 LTC1553CG#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1553CG#TRPBF?
All LTC1553CG#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1553CG#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 LTC1553CG#TRPBF part is unused and in its original packaging.
Return procedure for LTC1553CG#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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