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Analog Devices Inc. LTC7821EUH#PBF
- Part No.:
- LTC7821EUH#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC7821EUH#PBF.pdf
- Description:
- IC REG CTRLR BUCK HYBRID 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:197
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Product details
Overview
LTC7821EUH#PBF from Analog Devices is a hybrid synchronous step-down controller implementing soft-switching charge pump + buck architecture 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 LTC7821EUH#PBF datasheet, LTC7821EUH#PBF pinout, LTC7821EUH#PBF application, or LTC7821EUH#PBF equivalent, key selection considerations include its hybrid topology's soft-switching advantage over conventional controllers, RSENSE/DCR current sensing flexibility, monotonic start-up behavior, and precise capacitor balancing control for flying-capacitor stability.
Technical Context
The LTC7821EUH#PBF integrates a proprietary hybrid architecture combining a soft-switching charge pump stage with a synchronous buck stage-enabling zero-voltage switching (ZVS) on high-side switches to reduce switching losses and EMI. Its control loop uses an error amplifier (EA) with transconductance gm = 2 mmho and ITH-based current limit programming.
It features dual-stage capacitor balancing: pre-startup balancing of CFLY and CMID to VIN/2 via TIMER-pin-controlled current sources, and runtime monitoring of MID_SENSE against a resistor-programmable window set by HYS_PRGM. The PLL-enabled MODE/PLLIN pin allows phase-locking to external clocks up to 1.5MHz for multiphase synchronization.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 10V to 72V (80V absolute max); enables direct use in 48V telecom and industrial intermediate bus rails without pre-regulation. |
| VOUT Accuracy | ±1% over line/load/temperature; ensures stable 12V output for sensitive downstream logic and ASICs without post-regulation. |
| fSW Range | 200kHz to 1.5MHz (programmable via FREQ pin); higher frequencies allow smaller inductors (e.g., 2µH) and faster load transient response. |
| Current Sensing | RSENSE or DCR option; supports low-loss, Kelvin-connected sensing networks for accurate peak-current mode control. |
| Capacitor Balancing | Automatic CFLY/CMID charging to VIN/2 during startup and fault recovery; eliminates manual pre-biasing and prevents asymmetric voltage stress. |
| Thermal Protection | TEMP pin with 1.25V trip threshold (100ms timeout); enables PCB hot-spot monitoring using external PTC resistor. |
| Package | 32-pin 5mm × 5mm QFN with exposed pad (Pin 33 = SGND); optimized for thermal dissipation (θJC = 7.3°C/W) in high-power density layouts. |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN with exposed thermal pad (Pin 33 = SGND), rated for –40°C to 125°C 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 flying-capacitor and mid-rail switching nodes. |
| MID, MID_SENSE | Half-supply rail monitor | MID provides VIN/2 reference; MID_SENSE enables Kelvin sensing for window-comparator-based fault detection. |
| TG1, TG2, BG1, BG2 | Floating gate drivers | TG1/TG2 drive upper MOSFETs referenced to SW1/SW3; BG1/BG2 drive lower MOSFETs referenced to PGND or MID. |
| BOOST1–BOOST3 | Bootstrap supplies | Provide floating bias for TG1/BG1 (BOOST1), TG2/BG2 (BOOST2), and SW3-referenced driver (BOOST3). |
| ITH, VFB, ISNS+, ISNS− | Control loop interfaces | ITH sets peak current limit; VFB closes output voltage loop; ISNS± enable precision current sensing with ±50mV threshold. |
| RUN, FAULT, PGOOD | System control/status | RUN enables operation above 1.3V; FAULT asserts on capacitor imbalance or overtemperature; PGOOD indicates ±7.5% VOUT regulation. |
Key Features
| Feature | Design Value |
|---|---|
| Hybrid soft-switching topology | Reduces switching losses and EMI vs. hard-switched buck controllers - enables 500kHz operation with >97% efficiency in 48V→12V conversion. |
| Programmable operating mode | Select CCM, DCM, or Burst Mode® via MODE/PLLIN pin - optimizes light-load efficiency without compromising transient response. |
| Accurate capacitor balancing | Internal current sources and TIMER-pin timing ensure CFLY and CMID settle precisely to VIN/2 before enabling switching - prevents device overstress. |
| EXTVCC input | Accepts external 7V–40V supply to power INTVCC LDO - improves efficiency by bypassing internal VIN-derived regulator under high-VIN conditions. |
| Monotonic start-up | TRACK/SS pin controls regulated ramp of VFB - avoids output voltage overshoot and ensures controlled sequencing with other rails. |
Applications
| Telecom Intermediate Bus | High-Density Server PSU |
|---|---|
|
Use Scenario: 48V backplane powering multiple 12V point-of-load converters in 1RU server chassis. IC Role / Device Role / Timing Role: Primary intermediate bus converter delivering 20A at 12V with <100ns transient response and <10mV ripple. Use Value: Hybrid topology achieves >97% efficiency at 500kHz, reducing heat sink size and enabling fanless operation in thermally constrained enclosures. |
Use Scenario: Distributed 12V rail generation across multi-board compute modules with strict EMI compliance (CISPR 32 Class B). IC Role / Device Role / Timing Role: Synchronized multiphase controller using CLKOUT and MODE/PLLIN pins to align switching edges across parallel LTC7821EUH#PBF units. Use Value: Soft-switching reduces high-frequency harmonics, easing filter design and eliminating need for ferrite beads on output. |
| Automotive ADAS Power | Industrial PLC Backplane |
|
Use Scenario: 24V vehicle battery powering 12V vision processing subsystem with ASIL-B functional safety requirements. IC Role / Device Role / Timing Role: Fault-tolerant controller with independent FAULT/PGOOD signaling, TEMP pin for board hotspot monitoring, and UVLO hysteresis (0.28V). Use Value: Built-in capacitor balancing and monotonic start-up prevent inrush-induced voltage collapse during cold-crank conditions (down to 6V). |
Use Scenario: 48V industrial DC bus supplying isolated 12V/5V rails for I/O modules in harsh factory environments. IC Role / Device Role / Timing Role: Robust controller with ±1% VOUT accuracy over –40°C to 125°C, EXTVCC support for auxiliary supply redundancy, and RSENSE/DCR flexibility for aging-resistant current sensing. Use Value: Wide temperature rating and integrated protection (overvoltage, undervoltage, overtemperature) eliminate need for external supervision ICs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar hybrid/hard-switched step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC7820IUH#PBF | Lower VIN range (4.5V–60V), no capacitor balancing, fixed 500kHz fSW, no CLKOUT or MODE/PLLIN. | Suitable for simpler 12V/24V input systems without flying-capacitor topology or multiphase sync needs. | Select when hybrid topology complexity is unnecessary and cost sensitivity outweighs efficiency gains. |
| MP2918GL-Z | Hard-switched 4-switch buck-boost controller; no soft-switching; supports 4.5V–60V VIN; lacks MID_SENSE, TIMER, or HYS_PRGM pins. | Used where bidirectional capability or wider VOUT range is required, but EMI and peak efficiency are secondary. | Choose only if topology flexibility (buck-boost) is mandatory and >97% efficiency at high fSW is not required. |
Compared with LTC7820IUH#PBF and MP2918GL-Z, the LTC7821EUH#PBF uniquely delivers soft-switching benefits in a fixed-step-down configuration, enabling higher efficiency at elevated frequencies while maintaining tight output regulation and robust capacitor management - critical for high-density, low-EMI intermediate bus designs.
Availability
LTC7821EUH#PBF is available at Aetrix Electronics and suitable for telecom power systems, high-current server PSUs, automotive ADAS modules, and industrial PLC backplanes requiring stable component supply and long-term lifecycle support.
Supply support for LTC7821EUH#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 precision instrumentation, communications, and power management markets.
The LTC7821EUH#PBF belongs to Analog Devices' Power by Linear™ controller family, designed specifically for high-efficiency, low-EMI intermediate bus conversion using innovative hybrid topologies - targeting next-generation datacenter, telecom, and automotive power architectures.
FAQ
What is the primary topology implemented by the LTC7821EUH#PBF?
The LTC7821EUH#PBF implements a proprietary hybrid topology combining a soft-switching charge pump stage with a synchronous step-down stage. This architecture enables zero-voltage switching on high-side MOSFETs, significantly reducing switching losses and EMI compared to conventional hard-switched controllers - a core differentiator confirmed in the datasheet's block diagram and typical application circuits.
Does the LTC7821EUH#PBF require external MOSFETs, and what is its gate drive capability?
Yes, the LTC7821EUH#PBF is a controller-only IC and requires four external N-channel MOSFETs (M1–M4). Its gate drivers deliver 2Ω pull-up and 1Ω pull-down resistance with 4ns rise/fall times, supporting fast switching at up to 1.5MHz. The datasheet specifies TG1/TG2 and BG1/BG2 outputs with defined voltage swing ranges tied to SW1, SW3, and INTVCC rails.
How does the LTC7821EUH#PBF handle flying capacitor (CFLY) and mid-rail capacitor (CMID) balancing?
The LTC7821EUH#PBF performs automatic capacitor balancing using internal current sources controlled by the TIMER pin. During startup, it charges CFLY and CMID to VIN/2 before enabling switching. During operation, it monitors MID_SENSE against a window set by HYS_PRGM; deviation triggers rebalancing and FAULT assertion - all explicitly detailed in the "Capacitor Balancing Phase" section of the datasheet.
Can the LTC7821EUH#PBF operate without an external reference, and what is its default feedback voltage?
Yes, the LTC7821EUH#PBF operates with its internal 0.8V reference by default. When EXT_REF is left unconnected or tied to INTVCC, VFB is regulated to 0.8V ±1%. The datasheet confirms VFB = 0.792V to 0.808V (typical 0.8V) under all operating conditions, and optional external references (0.4V–0.9V clamped) are supported via the EXT_REF pin.
What thermal protection mechanisms are built into the LTC7821EUH#PBF?
The LTC7821EUH#PBF includes die temperature monitoring via the TEMP pin, which trips at 1.25V (±30mV) with 100ms timeout and hysteresis. An external PTC resistor forms a voltage divider with the TEMP pin to detect PCB hot spots. Upon trip, switching halts, FAULT asserts, and the device retries after timeout - fully documented in the Absolute Maximum Ratings and Electrical Characteristics tables.
LTC7821EUH#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)
LTC7821EUH#PBF FAQ
1.How can I place an order for LTC7821EUH#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC7821EUH#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 LTC7821EUH#PBF reliable?
The price and inventory of LTC7821EUH#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC7821EUH#PBF is usually 5 days.
3.What payment methods are accepted for LTC7821EUH#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC7821EUH#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC7821EUH#PBF?
LTC7821EUH#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC7821EUH#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 LTC7821EUH#PBF?
For technical support, including LTC7821EUH#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC7821EUH#PBF requirements.
6.How does Aetrix verify that LTC7821EUH#PBF is sourced from the original manufacturer or authorized distributors?
All LTC7821EUH#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 LTC7821EUH#PBF meets industry standards.
7.What is the process for return or replacement of LTC7821EUH#PBF?
All LTC7821EUH#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC7821EUH#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 LTC7821EUH#PBF part is unused and in its original packaging.
Return procedure for LTC7821EUH#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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