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Texas Instruments TPS65251-3RHAT
- Part No.:
- TPS65251-3RHAT
- Manufacturer:
- Texas Instruments
- Package:
- 40-VFQFN Exposed Pad
- Datasheet:
-
TPS65251-3RHAT.pdf
- Description:
- IC REG BCK ADJ 3A/2A TRPL 40VQFN
- Quantity:
- Payment:
- Shipping:
Inventory:174
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Product details
Overview
TPS65251-3RHAT from Texas Instruments is a triple-output synchronous buck converter IC for multi-rail power management in wide-input industrial and consumer systems. It integrates three high-current DC/DC converters (3 A / 2 A / 2 A), supports 4.5–18 V input, delivers adjustable outputs from 0.8 V to VIN−1 V, and features independent enable, soft-start, and current-limit pins per channel - used in set-top boxes and automotive infotainment.
For engineers reviewing the TPS65251-3RHAT datasheet, TPS65251-3RHAT pinout, TPS65251-3RHAT application, or TPS65251-3RHAT equivalent, key selection criteria include per-channel current limit adjustability via RLIM resistors, 180° out-of-phase Buck 1/Buck 2 operation to reduce input ripple, 256-ms factory-set PGOOD reset delay, and VQFN-40 (6 mm × 6 mm) thermal performance with RθJA = 32.7°C/W.
Technical Context
The TPS65251-3RHAT implements peak current-mode control with integrated high-side and low-side MOSFETs per buck stage (RDS(on) = 95/50 mΩ for Buck 1; 120/80 mΩ for Buck 2 & 3), enabling stable regulation and simplified RC compensation. Its oscillator supports resistor-programmed switching frequency (300 kHz–2.2 MHz) or external synchronization via SYNC pin after PGOOD assertion.
Each buck channel operates independently with dedicated ENx, SSx, FBx, COMPx, and RLIMx pins; Buck 1 and Buck 2 run 180° out-of-phase while Buck 2 and Buck 3 are in-phase - reducing input capacitor RMS current and EMI. The device includes two internal LDOs (3.3 V and 6.5 V) and an active-high open-drain PGOOD output with factory-configured 256-ms reset timeout.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input voltage range | 4.5 V to 18 V - supports 5/9/12/15-V system rails without external pre-regulation. |
| Output current (Buck 1) | 3 A continuous, 3.5 A peak - sufficient for main SoC core supply in DTV and car audio applications. |
| Output current (Buck 2 & 3) | 2 A continuous, 2.5 A peak each - suitable for I/O, memory, and peripheral rails. |
| Switching frequency | 300 kHz to 2.2 MHz - adjustable via ROSC resistor or external SYNC clock for EMI optimization. |
| PGOOD reset timeout | 256 ms (factory-set for TPS65251-3) - defines minimum system reset hold time before host processor release. |
| Thermal resistance | RθJA = 32.7°C/W - enables 3.5-W dissipation at ΔT = 115°C with standard PCB layout. |
| Feedback reference | 0.8 V ±2% - sets output voltage via external resistor divider; supports precise low-voltage rails (e.g., 1.2 V, 1.8 V, 3.3 V). |
Pinout & Package
VQFN-40 (RHA) package, 6.00 mm × 6.00 mm body, exposed thermal pad connected to GND.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN1, EN2, EN3 | Individual enable inputs | Active-high logic; weak internal 1-µA pull-up to V3V allows auto-enable; add capacitor for delayed start-up (~1.67 ms/nF). |
| SS1, SS2, SS3 | Soft-start charge nodes | 5-µA internal current source charges external capacitor; 4.7 nF yields ~1-ms soft-start time per channel. |
| FB1, FB2, FB3 | Feedback inputs | Monitor output voltage via resistor divider referenced to 0.8-V internal reference; supports pre-biased start-up. |
| RLIM1, RLIM2, RLIM3 | Current limit programming | Resistor-to-GND sets peak inductor current: Buck 1 (100–300 kΩ → 1.2–4.1 A), Buck 2/3 (1.1–5.1 kΩ → 1.2–4.1 A). |
| SYNC | External clock input | Accepts 0.2–2.2 MHz sync signal; ignored during startup; requires PGOOD assertion before synchronization engages. |
| PGOOD | Power-good status | Open-drain active-high output asserted only when all three outputs are ≥90% of nominal and sequencing completes; 256-ms reset timer. |
Key Features
| Feature | Design Value |
|---|---|
| Per-channel current limit adjustment | RLIM pins allow precise inductor sizing and overcurrent protection tuning - reduces BOM cost and improves fault margin. |
| 180° out-of-phase Buck 1/Buck 2 operation | Minimizes input ripple current by canceling harmonic components - lowers required input capacitance and EMI filter size. |
| Independent soft-start and enable per buck | Enables flexible power sequencing (e.g., core before I/O) without external controllers or timing circuits. |
| Automatic PFM/PWM mode transition | Improves light-load efficiency while maintaining <2% output ripple - eliminates need for external mode-control logic. |
| Integrated bootstrap regulators | BST1/BST2/BST3 pins drive high-side FET gates using 47-nF ceramic capacitors - simplifies layout and ensures robust gate drive. |
Applications
| Set-Top Box Power Management | Automotive Infotainment System |
|---|---|
Use Scenario: Multi-rail power delivery for SoC, DDR memory, and HDMI interface in cable/satellite STBs. IC Role / Device Role / Timing Role: Primary triple-buck PMIC providing 1.2-V core, 1.8-V memory, and 3.3-V I/O rails with sequenced startup. Use Value: 180° phase shift between Buck 1 and Buck 2 cuts input ripple by >50%, reducing 10-µF X7R input caps per rail. | Use Scenario: Centralized power for head-unit display controller, audio DSP, and CAN interface modules. IC Role / Device Role / Timing Role: High-current synchronous buck regulator delivering 3.3-V MCU supply, 5-V display backlight, and 12-V audio amplifier bias. Use Value: 256-ms PGOOD timeout ensures reliable microcontroller reset timing in automotive cold-crank conditions. |
| Blu-ray Disc Player | Security Camera DVR |
Use Scenario: Powering laser diode driver, video decoder SoC, and USB PHY in optical disc players. IC Role / Device Role / Timing Role: Triple-output DC/DC converter generating 1.1-V SoC core, 1.8-V video processing, and 3.3-V interface rails. Use Value: Adjustable RLIM resistors allow optimized current limits matching laser diode transient loads without overdesigning inductors. | Use Scenario: Compact power solution for multi-sensor IP cameras with H.264 encoding and PoE interface. IC Role / Device Role / Timing Role: Integrated buck regulator supplying 1.2-V image sensor, 1.8-V encoder, and 5-V PoE PD controller. Use Value: LOW_P pin enables forced PWM mode during motion-triggered recording, ensuring consistent 500-kHz switching for predictable EMI profile. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-buck power management applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS65251-1RHAT | Identical architecture and pinout; differs only in PGOOD reset timeout (1000 ms vs. 256 ms). | Suitable where longer system reset hold time is required (e.g., complex FPGA configuration). | Select TPS65251-1RHAT if extended reset duration improves boot reliability in large SoC systems. |
| TPS65251-2RHAT | Same silicon and package; PGOOD reset timeout is 32 ms (vs. 256 ms for TPS65251-3RHAT). | Better suited for fast-boot consumer devices like portable media players. | Choose TPS65251-2RHAT when minimal boot latency is critical and system firmware tolerates shorter reset windows. |
Compared with TPS65251-1RHAT and TPS65251-2RHAT, the TPS65251-3RHAT provides a mid-range 256-ms PGOOD timeout - balancing robustness against cold-start voltage sag and responsiveness for automotive and broadcast equipment where deterministic reset timing is essential.
Availability
TPS65251-3RHAT is available at Aetrix Electronics and suitable for set-top box, automotive infotainment, and security camera DVR applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for TPS65251-3RHAT 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
Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of expertise in power management IC design and high-volume manufacturing.
The TPS65251-x family is designed for compact, high-efficiency multi-rail power delivery in space-constrained consumer and industrial systems - emphasizing integration, thermal performance, and flexible sequencing control.
FAQ
What is the PGOOD reset timeout value for TPS65251-3RHAT?
The TPS65251-3RHAT has a factory-configured PGOOD reset timeout of 256 ms. This value is fixed and non-adjustable; it defines the minimum time the PGOOD signal remains low after power-up until all three buck outputs reach ≥90% of their nominal voltages and sequencing completes. This timing ensures reliable microcontroller or FPGA initialization in automotive and broadcast applications where input voltage stability may vary during cold cranking or brown-out events. The TPS65251-3RHAT part number guarantees this specific timeout value.
How does the TPS65251-3RHAT achieve reduced input ripple?
The TPS65251-3RHAT reduces input ripple through 180° out-of-phase operation between Buck 1 and Buck 2, while Buck 2 and Buck 3 run in-phase. This interleaving cancels fundamental and harmonic components of input current, lowering RMS ripple by up to 50% compared to in-phase operation. As a result, designers can use smaller input capacitors (e.g., single 10-µF X7R per rail) and reduce EMI filter complexity. The phase relationship is hardwired and requires no external configuration - it is inherent to the TPS65251-3RHAT's internal oscillator architecture.
Can the TPS65251-3RHAT operate with different input voltages per buck channel?
Yes, the TPS65251-3RHAT supports independent input supplies: VIN1, VIN2, and VIN3 are separate pins, allowing each buck channel to be powered from distinct sources (e.g., 12 V for Buck 1, 5 V for Buck 2, and 9 V for Buck 3). Each input must remain within the 4.5–18 V operating range and be bypassed with a 10-µF ceramic capacitor. This flexibility enables mixed-voltage system designs, such as powering a high-current SoC rail from a main DC bus while deriving lower-power I/O rails from auxiliary supplies - all managed by a single TPS65251-3RHAT IC.
What is the purpose of the LOW_P pin on the TPS65251-3RHAT?
The LOW_P pin on the TPS65251-3RHAT controls the light-load operating mode: when pulled high (≥1.55 V), it enables automatic PFM/PWM transition for improved efficiency at partial load; when pulled low (≤1.24 V), it forces constant-frequency PWM mode across all load conditions. This ensures predictable switching frequency and minimized output ripple during dynamic operation - critical for noise-sensitive applications like audio amplifiers or RF subsystems. The pin's threshold is referenced to the internal V3V rail, and its state is sampled after PGOOD assertion. This behavior is identical across all TPS65251-x variants, including the TPS65251-3RHAT.
How is current limit configured for each buck channel in the TPS65251-3RHAT?
Current limit for each buck channel in the TPS65251-3RHAT is configured externally via a resistor from RLIMx to GND: RLIM1 sets Buck 1 limit (100–300 kΩ → 1.2–4.1 A), while RLIM2 and RLIM3 set Buck 2 and Buck 3 limits (1.1–5.1 kΩ → 1.2–4.1 A). These resistors directly program peak inductor current, enabling precise overcurrent protection and optimal inductor selection. The relationship is monotonic and documented in the datasheet's Figure 6-6 through 6-18. No calibration or trimming is required - the TPS65251-3RHAT interprets resistance values directly, making current limit setup deterministic and repeatable across production units.
TPS65251-3RHAT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 40-VFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 3
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 18V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 17V
- Current - Output:
- 3A, 2A
- Frequency - Switching:
- 300kHz ~ 2.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 40-VQFN (6x6)
TPS65251-3RHAT FAQ
1.How can I place an order for TPS65251-3RHAT through Aetrix?
Please submit a Request for Quotation (RFQ) for TPS65251-3RHAT 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 TPS65251-3RHAT reliable?
The price and inventory of TPS65251-3RHAT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TPS65251-3RHAT is usually 5 days.
3.What payment methods are accepted for TPS65251-3RHAT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TPS65251-3RHAT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TPS65251-3RHAT?
TPS65251-3RHAT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TPS65251-3RHAT 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 TPS65251-3RHAT?
For technical support, including TPS65251-3RHAT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TPS65251-3RHAT requirements.
6.How does Aetrix verify that TPS65251-3RHAT is sourced from the original manufacturer or authorized distributors?
All TPS65251-3RHAT 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 TPS65251-3RHAT meets industry standards.
7.What is the process for return or replacement of TPS65251-3RHAT?
All TPS65251-3RHAT units undergo pre-shipment inspection (PSI). If there is an issue with TPS65251-3RHAT, 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 TPS65251-3RHAT part is unused and in its original packaging.
Return procedure for TPS65251-3RHAT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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