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Analog Devices Inc. LTC7821IUH#PBF
- Part No.:
- LTC7821IUH#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC7821IUH#PBF.pdf
- Description:
- IC REG CTRLR BUCK HYBRID 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,875
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Product details
Overview
LTC7821IUH#PBF from Analog Devices is a hybrid synchronous step-down controller combining soft-switching charge pump and buck topology for high-efficiency intermediate bus conversion. It operates from 10V to 72V input, delivers ±1% output voltage accuracy at 12V, supports 200kHz–1.5MHz programmable switching frequency, and achieves >97% efficiency in 48V-to-12V/20A applications. It is used in telecom power systems requiring low EMI and fast transient response.
For engineers reviewing the LTC7821IUH#PBF datasheet, LTC7821IUH#PBF pinout, LTC7821IUH#PBF application, or LTC7821IUH#PBF equivalent, key selection criteria include its hybrid architecture enabling high-frequency operation without sacrificing efficiency, RSENSE/DCR current sensing flexibility, monotonic start-up, and accurate current sharing for multiphase paralleling.
Technical Context
The LTC7821IUH#PBF implements a proprietary hybrid architecture that integrates a soft-switching charge pump stage with a synchronous buck converter, eliminating hard-switching losses in high-side switches and reducing EMI generation. Its control loop uses an error amplifier (EA) with transconductance gm = 2 mmho and ITH-based peak current mode control.
It features dual-stage capacitor balancing-pre-startup CFLY/CMID charging to VIN/2 via TIMER-pin-controlled current sources, and runtime MID_SENSE window monitoring with HYS_PRGM-programmable threshold. The integrated PLL enables phase-lockable synchronization across multiple controllers for interleaved operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 10V to 72V (80V absolute max); supports 48V/60V intermediate bus rails common in datacom and storage systems. |
| VOUT Accuracy | ±1% over line/load/temperature; ensures stable 12V output regulation without external trimming in precision power systems. |
| fSW Range | 200kHz to 1.5MHz (programmable via FREQ pin); enables compact magnetics and fast load transient response. |
| Current Sensing | RSENSE or DCR options; allows flexible, low-loss inductor current measurement compatible with standard PCB layouts. |
| Operating Temp | –40°C to +125°C junction; qualified for automotive under-hood and industrial embedded environments. |
| Package | 32-pin 5mm × 5mm QFN with exposed thermal pad; provides low θJC = 7.3°C/W for high-power density designs. |
| Efficiency | >97% at 48V→12V/20A/500kHz; reduces thermal stress and system cooling requirements versus conventional controllers. |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN with exposed SGND pad (Pin 33), rated for –40°C to +125°C operating junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW1, SW3 | Switch node connections | SW1 swings from VIN/2 to VIN; SW3 swings from GND to VIN/2 - defines charge pump flying capacitor endpoints. |
| MID / MID_SENSE | Half-supply monitoring node | MID provides Kelvin-sensed VIN/2 reference; MID_SENSE feeds window comparator for fault detection during normal operation. |
| BOOST1–BOOST3 | Floating gate drive supplies | Provide bootstrapped voltages for TG1/BG1/TG2/BG2 drivers; BOOST1 swings up to (VIN + INTVCC), BOOST2 fixed at (VIN/2 + INTVCC). |
| ITH | Error amplifier output & current threshold | Controls peak inductor current via voltage-programmed current comparator; sets loop bandwidth and transient performance. |
| TRACK/SS | Soft-start and tracking input | Regulates VFB to lowest of 0.8V, EXT_REF, or TRACK/SS voltage; internal 10µA pull-up enables RC ramp or supply tracking. |
| MODE/PLLIN | Mode select or sync input | Configures CCM/DCM/Burst Mode when grounded/INTVCC/floating; accepts external clock for phase-locked multiphase operation. |
Key Features
| Feature | Design Value |
|---|---|
| Hybrid soft-switching architecture | Eliminates turn-on loss in high-side MOSFETs, enabling >97% efficiency at 500kHz - unattainable with conventional buck controllers at same frequency. |
| Capacitor balancing circuitry | Automatic pre-startup and runtime balancing of CFLY and CMID to VIN/2 using TIMER-pin-controlled current sources and HYS_PRGM-set window thresholds. |
| Programmable operating modes | Select forced CCM, DCM, or Burst Mode® via MODE/PLLIN pin; optimizes light-load efficiency without external components. |
| Accurate current sharing | Enables parallel operation of multiple LTC7821IUH#PBF controllers with <±5% current mismatch - critical for >40A distributed power rails. |
| EXTVCC input | Accepts external 7V–40V supply to power INTVCC LDO, bypassing VIN-derived regulator and improving overall system efficiency by ~1.2% at full load. |
Applications
| Intermediate Bus Converter | High-Current Distributed Power |
|---|---|
|
Use Scenario: 48V backplane supplying 12V to multiple server blades in a rack-mounted telecom switch. IC Role / Device Role / Timing Role: Primary non-isolated DC-DC controller managing bulk power conversion with soft-switching to meet EN55022 Class B EMI limits. Use Value: Achieves >97% efficiency at 500kHz, allowing smaller inductors and reduced board area versus 150kHz alternatives while maintaining low noise. |
Use Scenario: Redundant 12V/60A power rail feeding FPGA, ASIC, and memory subsystems in AI accelerator modules. IC Role / Device Role / Timing Role: Synchronous controller in paralleled configuration, using CLKOUT and MODE/PLLIN for interleaved 180° phase alignment. Use Value: Enables precise current sharing (<±5%) and synchronized switching to minimize input/output ripple and simplify EMI filter design. |
| Automotive ADAS Domain Controller | Enterprise Storage Power Shelf |
|
Use Scenario: 48V battery-fed 12V intermediate rail powering radar SoCs and camera ISPs in autonomous driving ECUs. IC Role / Device Role / Timing Role: High-reliability step-down controller with monotonic start-up, overtemperature protection, and short-circuit recovery. Use Value: –40°C to +125°C rating and robust fault handling (FAULT/PGOOD signaling) ensure safe operation in under-hood thermal environments. |
Use Scenario: Hot-swappable 12V/100A power module in modular storage enclosures supporting NVMe SSD arrays. IC Role / Device Role / Timing Role: Core controller in scalable multi-phase design, leveraging RSENSE sensing and EXTVCC for efficiency optimization across load range. Use Value: Programmable burst mode and DCR sensing reduce no-load quiescent current to <240µA, minimizing standby power in idle bays. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar hybrid/hard-switching step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC7820IUH#PBF | Lower VIN range (4.5V–60V), no capacitor balancing, no MID_SENSE, fixed 500kHz fSW, no PLL sync. | Suitable for simpler 12V/24V input systems where VIN/2 stability isn't required and EMI constraints are less stringent. | Select LTC7820IUH#PBF only if hybrid topology benefits (soft switching, >97% efficiency at high fSW) are unnecessary and cost sensitivity dominates. |
| MPQ8633BGLE-Z | Monolithic 30V-input buck controller with integrated MOSFETs; no charge pump, no MID node, lower efficiency (~94% @ 48V→12V), no programmable modes. | Targeted at space-constrained, lower-power applications (<15A) where integration outweighs efficiency and EMI performance. | Choose MPQ8633BGLE-Z only for compact, low-complexity designs where external MOSFETs and layout control are not required. |
Compared with LTC7820IUH#PBF and MPQ8633BGLE-Z, the LTC7821IUH#PBF uniquely delivers hybrid soft-switching efficiency at high frequencies, mandatory capacitor balancing for stable VIN/2 generation, and full programmability - making it the only option for demanding 48V→12V/20A+ telecom and storage applications.
Availability
LTC7821IUH#PBF is available at Aetrix Electronics and suitable for telecom infrastructure, enterprise storage systems, and automotive ADAS domain controllers requiring stable component supply, long lifecycle support, and guaranteed industrial temperature grade.
Supply support for LTC7821IUH#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, communications, automotive, and aerospace markets.
The LTC7821IUH#PBF belongs to Analog Devices' Power by Linear™ controller family, designed specifically for high-efficiency, high-density intermediate bus conversion using innovative hybrid topologies to overcome traditional buck limitations.
FAQ
What is the primary function of the LTC7821IUH#PBF in a power system?
The LTC7821IUH#PBF functions as a hybrid synchronous step-down controller that merges a soft-switching charge pump with a buck converter to achieve high efficiency and low EMI. Unlike conventional controllers, it regulates output voltage by controlling four external N-channel MOSFETs in a unique topology where SW1 and SW3 define flying capacitor endpoints, and MID serves as the VIN/2 reference node. This architecture enables >97% efficiency at 500kHz in 48V-to-12V conversion, making LTC7821IUH#PBF ideal for high-density intermediate bus applications.
How does the capacitor balancing feature work in the LTC7821IUH#PBF?
The LTC7821IUH#PBF performs automatic capacitor balancing during startup and runtime using dedicated circuitry. At power-up, the TIMER pin controls current sources that charge CFLY and CMID to exactly VIN/2 before enabling switching. During normal operation, the MID_SENSE pin monitors deviation from VIN/2 against a window set by HYS_PRGM; if exceeded, switching halts and rebalancing initiates. This ensures stable half-supply generation critical for hybrid topology integrity - a function absent in standard buck controllers and essential for reliable LTC7821IUH#PBF operation.
Can the LTC7821IUH#PBF be synchronized to an external clock source?
Yes, the LTC7821IUH#PBF supports external synchronization via the MODE/PLLIN pin. When a clean clock signal is applied, the internal PLL locks the oscillator to that frequency and phase, enabling precise interleaving across multiple LTC7821IUH#PBF controllers. This capability is confirmed in the datasheet's "Oscillator and Phase Lock Loop" section, where fSYNC_LOW (200kHz) and fSYNC_HIGH (1500kHz) are specified. Synchronization eliminates beat frequencies, reduces input/output ripple, and improves thermal distribution - making it vital for multiphase LTC7821IUH#PBF deployments in high-current systems.
What are the key differences between the LTC7821IUH#PBF and LTC7820IUH#PBF?
The LTC7821IUH#PBF includes capacitor balancing, MID/MID_SENSE pins, MODE/PLLIN synchronization, and a wider VIN range (10V–72V) versus LTC7820IUH#PBF (4.5V–60V). Crucially, LTC7821IUH#PBF implements the full hybrid architecture with soft switching, enabling >97% efficiency at 500kHz, while LTC7820IUH#PBF is a simplified hard-switching controller lacking VIN/2 stabilization. These differences make LTC7821IUH#PBF mandatory for applications requiring strict EMI compliance and high-frequency efficiency - capabilities not present in LTC7820IUH#PBF.
Does the LTC7821IUH#PBF support both RSENSE and DCR current sensing?
Yes, the LTC7821IUH#PBF explicitly supports both RSENSE and DCR current sensing, as stated in its FEATURES list and confirmed in the "Current Sense Threshold vs ITH Voltage" graph (Figure 7821 G18). The ISNS+ and ISNS– pins accept Kelvin connections to either a discrete sense resistor or the DCR network of the output inductor. This dual-mode flexibility allows designers to optimize for accuracy (RSENSE) or cost/PCB area (DCR), and is a documented capability of the LTC7821IUH#PBF - unlike monolithic alternatives that restrict sensing methods.
LTC7821IUH#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 32-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 10V ~ 72V
- Frequency - Switching:
- 200kHz ~ 1.5MHz
- Duty Cycle (Max):
- 40%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-QFN (5x5)
LTC7821IUH#PBF FAQ
1.How can I place an order for LTC7821IUH#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC7821IUH#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 LTC7821IUH#PBF reliable?
The price and inventory of LTC7821IUH#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC7821IUH#PBF is usually 5 days.
3.What payment methods are accepted for LTC7821IUH#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC7821IUH#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC7821IUH#PBF?
LTC7821IUH#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC7821IUH#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 LTC7821IUH#PBF?
For technical support, including LTC7821IUH#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC7821IUH#PBF requirements.
6.How does Aetrix verify that LTC7821IUH#PBF is sourced from the original manufacturer or authorized distributors?
All LTC7821IUH#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 LTC7821IUH#PBF meets industry standards.
7.What is the process for return or replacement of LTC7821IUH#PBF?
All LTC7821IUH#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC7821IUH#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 LTC7821IUH#PBF part is unused and in its original packaging.
Return procedure for LTC7821IUH#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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