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Analog Devices Inc. LTC1703CG#PBF
- Part No.:
- LTC1703CG#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 28-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1703CG#PBF.pdf
- Description:
- IC REG CTRLR MOBILE 2OUT 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,360
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Product details
Overview
LTC1703CG#PBF from Analog Devices (formerly Linear Technology) is a dual-channel, synchronous buck controller optimized for mobile Pentium III microprocessor core and I/O supplies. It delivers two independent 550kHz PWM outputs driving external N-channel MOSFETs, supports Intel Mobile VID programming (0.9V–2.0V in 25mV/50mV steps) on Channel 1, features internal 0.8V ±1% reference, and operates from 4.5V–5.5V input with up to 15A per channel output capability.
For engineers reviewing the LTC1703CG#PBF datasheet, LTC1703CG#PBF pinout, LTC1703CG#PBF application, or LTC1703CG#PBF equivalent, key selection criteria include dual-phase interleaved operation for reduced input ripple, VID-compliant digital voltage scaling, no external current sense resistor requirement, and support for high-efficiency 2-step power architectures in space-constrained portable systems.
Technical Context
The LTC1703CG#PBF implements two independent voltage-mode PWM controllers with 550kHz fixed-frequency oscillation and 180° phase offset between channels to minimize input capacitor RMS current. Each channel integrates high-current gate drivers (TG/BG) with 0.5Ω RON, internal 25MHz GBW error amplifier, and VDS-based current limiting-eliminating need for external sense resistors.
Channel 1 includes a 5-bit VID DAC with internal pull-up resistors (40kΩ) and diode-clamped inputs compliant with Intel Mobile VID specification; Channel 2 uses standard resistor-divider feedback. The FCB pin forces continuous conduction mode, while FAULT provides latched overvoltage protection (>15% trip threshold, 25µs delay).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 550kHz fixed; enables compact 1µH inductors and low-ESR ceramic output capacitors |
| Output Voltage Range (Ch1) | 0.9V–2.0V in 25mV/50mV steps via VID0–VID4; supports dynamic CPU voltage scaling |
| Reference Voltage | 0.800V ±1% (25°C); ensures ≤±1.5% total DC output regulation without trimming |
| Max Output Current | 15A per channel; sustained delivery enabled by dual-phase interleaving and low-RON drivers |
| Operating Temp Range | 0°C to +85°C (C-grade); validated for notebook and embedded industrial applications |
| Shutdown Current | <100µA with both RUN/SS pins grounded; critical for battery-powered system standby |
| Package | 28-pin SSOP; 5.6mm × 10.2mm footprint compatible with automated SMT assembly |
Pinout & Package
Package: 28-pin Plastic SSOP (G package), 0.025" pitch, JEDEC MS-012AC, body size 5.6mm × 10.2mm, 1.75mm max height.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PVCC (1) | Driver Power Supply | Supplies BG/TG drivers; must be ≥VGS(ON) of QB/QT MOSFETs; bypassed to PGND with ≥1µF |
| BOOST1 (2) | Top-Gate Floating Supply | Charges bootstrap capacitor for TG1; requires 1µF cap to SW1 and optional Schottky from VIN |
| BG1 (3) | Bottom-Gate Driver Output | Drives QB1 source-follower; sinks up to 5A peak; pulled high during FAULT latch |
| TG1 (4) | Top-Gate Driver Output | Floating driver for QT1; powered from BOOST1; returns to SW1 node |
| SW1 (5) | Switching Node | Connects to QT1 drain/QB1 source; used for VDS current sensing and TG1 return path |
| IMAX1 (6) | Current Limit Threshold | Sets overcurrent trip via Kelvin-connected resistor to QB1 source; internal 10µA pull-up |
| FCB (7) | Force Continuous Mode | Pull to SGND to disable Burst Mode; enables third-output generation via auxiliary winding |
| RUN/SS1 (8) | Enable & Soft-Start Control | Pull low to disable Ch1; 3.5µA internal current source sets ramp rate (≈50ms/µF) |
| COMP1 (9) | Error Amplifier Output | Connects RC network for loop compensation; interfaces directly with PWM comparator |
| SGND (10) | Signal Ground Reference | Return for FB/COMP/RUN/SS; must be separated from PGND except at single point near CIN |
| FB1 (11) | Channel 1 Feedback Input | Internally connected to VID resistor network; sets VOUT1 without external divider |
| SENSE (12) | Output Sense Return | Connected to VOUT1; completes VID feedback path; improves load regulation accuracy |
| VID0–VID4 (13–17) | Digital Voltage Programming | 5-bit code selects VOUT1 per Intel Mobile VID table; each pin has 40kΩ pull-up + diode clamp |
| VCC (18) | Analog Core Supply | 3V–7V supply for internal circuits; bypassed to SGND with ≥1µF capacitor |
| FB2 (19) | Channel 2 Feedback Input | Standard resistor-divider input; independent of VID; requires external R-divide network |
| COMP2 (20) | Channel 2 Error Amplifier Output | Identical function to COMP1; separate compensation network required |
| RUN/SS2 (21) | Channel 2 Enable & Soft-Start | Independent control of Ch2; simultaneous grounding disables entire IC |
| FAULT (22) | Latched Overvoltage Flag | Open-drain output; pulls high on >15% VOUT overvoltage; requires power cycle to reset |
| PGND (23) | Power Ground Return | Return for BG drivers and high-current paths; connect near QB1/QB2 sources and CIN– |
| SW2 (24) | Channel 2 Switching Node | Identical role to SW1; connects to QT2 drain/QB2 source |
| TG2 (25) | Channel 2 Top-Gate Driver | Identical to TG1; powered from BOOST2; returns to SW2 |
| BG2 (26) | Channel 2 Bottom-Gate Driver | Identical to BG1; drives QB2; pulled high during FAULT |
| BOOST2 (27) | Channel 2 Top-Gate Supply | Identical to BOOST1; requires 1µF cap to SW2 |
| IMAX2 (28) | Channel 2 Current Limit Set | Identical to IMAX1; sets Ch2 overcurrent threshold with external resistor |
Key Features
| Feature | Design Value |
|---|---|
| Interleaved 2-phase operation | Reduces input capacitor RMS current by ~48% vs. single-phase, enabling smaller, lower-cost CIN |
| Integrated VID DAC (Ch1) | Eliminates external DAC and level-shifting circuitry; supports Intel Mobile VID voltage scaling protocol |
| VDS-based current sensing | Removes need for power-wasting external sense resistor; improves efficiency and thermal performance |
| 25MHz gain-bandwidth error amplifier | Enables complex pole-zero compensation for stable high-crossover loops and fast transient response |
| Burst Mode™ at light load | Automatically transitions to discontinuous conduction then Burst Mode to maintain >80% efficiency down to 100mA |
| Latched FAULT protection | Prevents damage from overvoltage events; holds outputs in safe state until power cycle |
Applications
| Mobile Pentium III Processor Core Supply | Microprocessor I/O Voltage Rail |
|---|---|
Use Scenario: Powers Intel Mobile Pentium III CPU core requiring dynamically scalable 0.9V–2.0V at up to 15A with tight regulation. IC Role / Device Role / Timing Role: Dual-channel synchronous buck controller providing VID-programmed voltage and independent I/O rail. Use Value: Achieves ≤±1.5% DC regulation and <±2.2% transient deviation using internal 0.8V reference and 25MHz error amplifier. | Use Scenario: Generates stable 1.5V/3A I/O supply synchronized with core rail in notebook platforms. IC Role / Device Role / Timing Role: Second independent buck controller (Ch2) with resistor-divider feedback and soft-start control. Use Value: Enables independent enable/disable sequencing and optimized compensation for I/O load profile. |
| Multi-Rail Logic Supply Generator | 2-Step Notebook Power Architecture |
Use Scenario: Generates dual regulated outputs (e.g., 1.2V/12A and 1.8V/5A) from shared 5V intermediate bus. IC Role / Device Role / Timing Role: Dual-phase controller minimizing input ripple and EMI in dense PCB layouts. Use Value: Reduces input RMS current from 9.3A to 4.8A, cutting I²R losses by 3.75× and easing thermal design. | Use Scenario: Secondary regulator in 2-step system where primary converts battery to 5V, LTC1703 converts 5V to CPU core voltage. IC Role / Device Role / Timing Role: High-efficiency, high-density buck controller operating from stable 5V intermediate bus. Use Value: Enables compact layout adjacent to CPU while offloading heat generation to primary 5V supply located remotely. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ISL6225CRZ-T | Single-channel 550kHz controller with VID; no integrated dual-phase logic or FCB pin | Requires two ICs for dual-rail; lacks interleaving benefit and Burst Mode optimization | Select when only one rail needs VID scaling and board area permits discrete dual implementation |
| TPS51220ARUKR | Single-chip dual-phase controller with integrated MOSFET drivers but no VID DAC; 300kHz switching | Fixed 0.6V reference; requires external VID interface circuitry; lower frequency increases inductor size | Select for cost-sensitive designs where VID is not required and larger magnetics are acceptable |
Compared with ISL6225CRZ-T and TPS51220ARUKR, the LTC1703CG#PBF uniquely combines native Intel Mobile VID compliance, true dual-phase interleaving, and VDS current sensing in a single SSOP-28 package-enabling higher integration, tighter regulation, and superior light-load efficiency without external components.
Availability
LTC1703CG#PBF is available at Aetrix Electronics and suitable for mobile processor core supplies, notebook multi-rail power systems, and 2-step intermediate-bus architectures requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC1703CG#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 precision instrumentation, communications, and power conversion markets.
The LTC1703CG#PBF belongs to Linear's legacy high-efficiency power controller product line, specifically engineered for mobile computing applications demanding dynamic voltage scaling, minimal PCB area, and robust thermal performance in dual-rail configurations.
FAQ
What is the maximum supported output current per channel for the LTC1703CG#PBF?
The LTC1703CG#PBF supports up to 15A per channel when paired with appropriately rated external N-channel MOSFETs (e.g., IRF7811 for QT1/QB1), 1µH inductors, and sufficient output capacitance (e.g., 180µF ×6). This rating assumes proper thermal management, 4.5V–5.5V input, and operation within the 0°C to +85°C ambient range specified for the C-grade device. The LTC1703CG#PBF itself does not limit current-external component selection and layout determine actual achievable current.
Does the LTC1703CG#PBF require an external current sense resistor?
No, the LTC1703CG#PBF does not require an external current sense resistor. It implements VDS-based current limiting by monitoring the voltage drop across the bottom N-channel MOSFET (QB1/QB2) during its on-state. The IMAX1/IMAX2 pins set the current limit threshold using a single external resistor to PGND, eliminating power loss and board space associated with traditional sense resistors. This architecture is confirmed in the datasheet's "Current Limit Loop" section and functional block diagram.
How does the VID interface on the LTC1703CG#PBF work, and which channel supports it?
The VID interface on the LTC1703CG#PBF is implemented exclusively on Channel 1 (pins VID0–VID4, FB1, SENSE) and conforms to the Intel Mobile VID specification. It uses internal 40kΩ pull-up resistors and diode clamps to accept logic-level inputs, generating precise 0.9V–2.0V outputs in 25mV/50mV steps per Table 1. Channel 2 (FB2) requires a standard resistor divider and is not VID-enabled. The LTC1703CG#PBF's internal VID network includes R11 (10kΩ) between SENSE and FB1, eliminating need for external feedback resistors on Ch1.
What is the purpose of the FCB (Force Continuous Bar) pin on the LTC1703CG#PBF?
FCB (Pin 7) on the LTC1703CG#PBF forces both converter channels into continuous conduction mode regardless of load, disabling automatic transition to discontinuous conduction or Burst Mode™. When FCB voltage drops below 0.8V (e.g., tied to SGND), synchronous operation is maintained at all loads. This is essential for noise-sensitive applications or when generating a third regulated output via auxiliary winding feedback. Leaving FCB floating is prohibited; it must be tied to VCC (default) or SGND (forced continuous).
Can the LTC1703CG#PBF operate with a 3.3V input supply?
No, the LTC1703CG#PBF cannot reliably operate with a 3.3V input supply. Its absolute maximum ratings specify VCC and PVCC minimums of 3V, but the recommended operating input range is 4.5V to 5.5V, as explicitly stated in the Typical Application schematic (VIN = 4.5V to 5.5V) and validated in efficiency curves (Figure 1). At 3.3V, the internal gate drivers may not fully enhance external N-channel MOSFETs, leading to excessive conduction losses, thermal runaway, and failure to meet regulation specs. The LTC1703CG#PBF is designed for 5V intermediate bus architectures.
LTC1703CG#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Controller, Mobile Intel Pentium® III
- Voltage - Input:
- 3V ~ 7V
- Number of Outputs:
- 2
- Voltage - Output:
- 0.9V ~ 2V
- Operating Temperature:
- 0°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SSOP
LTC1703CG#PBF FAQ
1.How can I place an order for LTC1703CG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1703CG#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 LTC1703CG#PBF reliable?
The price and inventory of LTC1703CG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1703CG#PBF is usually 5 days.
3.What payment methods are accepted for LTC1703CG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1703CG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1703CG#PBF?
LTC1703CG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1703CG#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 LTC1703CG#PBF?
For technical support, including LTC1703CG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1703CG#PBF requirements.
6.How does Aetrix verify that LTC1703CG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1703CG#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 LTC1703CG#PBF meets industry standards.
7.What is the process for return or replacement of LTC1703CG#PBF?
All LTC1703CG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1703CG#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 LTC1703CG#PBF part is unused and in its original packaging.
Return procedure for LTC1703CG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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