LTC2928CUHF - 4-Channel Power Supply Sequencer & Supervisor | ADI
N.º da peça: LTC2928CUHF ✓ Ativo| Qtd. | Preço unitário | Total |
|---|---|---|
| 1 | $11.5 | $11,50 |
| 10 | $10.35 | $103,50 |
| 100 | $8.95 | $895,00 |
| 500 | $7.65 | $3.825,00 |
| 1.000 | $5.98 | $5.980,00 |
LTC2928CUHF Visão geral
A power supply sequencer and supervisor is a mixed-signal IC that controls the order and timing in which multiple voltage rails are enabled during system power-up and disabled during power-down, while continuously monitoring each rail for under-voltage and over-voltage conditions. The LTC2928CUHF sits within the broader category hierarchy of supervisor IC -> voltage monitor -> power management IC -> semiconductor. Cascadable sequencers are essential building blocks in any multi-rail system where inrush current, latch-up, or DSP/FPGA/processor rail-ordering requirements preclude simultaneous rail activation.
Key features include four independent sequencer channels with adjustable thresholds, a single-wire cascade interface for expanding beyond four rails, programmable ramp and fault timing via external capacitors, and integrated over-voltage and under-voltage comparators with 1.5% accuracy. Each channel has a dedicated ON/OFF control line, and a FAULT pin aggregates fault events across channels. The device operates from 2.5V to 6V on VCC and supports monitoring of supplies up to 6V directly (higher voltages require external dividers).
The LTC2928 architecture uses an external timing capacitor per channel to program turn-on delay, turn-off delay, and fault-retry timing. The master CASC pin synchronizes multiple LTC2928 devices so that an unlimited number of power rails can be sequenced. Per-channel TIMER and SENSE pins interface to the supply being monitored, and the open-drain ON outputs drive external FETs or enable pins of downstream regulators.
Typical applications include multi-rail FPGA and DSP boards, ATCA/AdvancedTCA cards, telecom line cards, RAID storage controllers, and industrial controllers where multiple voltage domains must come up in a defined order. The device is also widely used in test and measurement chassis, network switches, and any hot-swap-friendly chassis requiring N+1 redundant power sequencing.
When designing with the LTC2928CUHF, place each SENSE pin bypass capacitor close to the IC, keep the timing-capacitor traces short, and use the cascade line as a single net between LTC2928 CASC pins if multiple ICs are stacked. For supplies above 6V, add a resistor divider on SENSE so the divided voltage falls inside the 0.5V to 1.0V threshold window. The exposed pad (Pin 39 on the QFN) must be soldered to the ground plane for thermal and electrical performance.
This page synthesizes distributor stock data, drop-in same-package alternatives, and practical design notes not collected on the manufacturer datasheet.
Alternativas drop-in para LTC2928CUHF — mesmo encapsulamento, compatível pino a pino. Peças de encapsulamento diferente que exigem retrabalho na PCB são excluídas.
Ferramenta de comparação rápida — selecione peças alternativas para comparação lado a lado:
LTC2928IUHF
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
LTC2928CUHF#TR
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
LTC2928CUHF#TRPBF
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
LTC2928IUHF#PBF
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
LTC2928IUHF#TRPBF
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
LTC2928CUHF Especificações
| Number of Monitored Channels | 4 |
| Supply Voltage (VCC) | 2.5 V to 6 V |
| Monitored Supply Range (with divider) | Up to 6 V direct, higher with external divider |
| Threshold Accuracy | 1.5 % |
| Cascade Support | Yes, unlimited LTC2928s via CASC pin |
| Programmable Turn-On Delay | Yes, external capacitor |
| Programmable Turn-Off Delay | Yes, external capacitor |
| Programmable Fault Retry Timing | Yes, external capacitor |
| Over-Voltage Detection | Yes |
| Under-Voltage Detection | Yes |
| FAULT Output | Yes (open-drain, aggregated) |
| ON Outputs | 4, open-drain channel enables |
| Faixa de temperatura de operação | 0 C to +70 C (C grade) |
| Package Type | 38-pin QFN (5x7 mm) with exposed pad |
| Tipo de montagem | Surface Mount |
| Status RoHS | Compliant (#PBF suffix) |
| 1ku List Price (Starting) | $5.98 |
Configuração de pinos do LTC2928CUHF
| Pino 1 | S1 — Sense input for channel 1 |
| Pino 2 | ON1 — Open-drain ON output for channel 1 |
| Pino 3 | T1 — Timing capacitor for channel 1 |
| Pino 4 | NC — Not connected (per datasheet) |
| Pino 5 | S2 — Sense input for channel 2 |
| Pino 6 | ON2 — Open-drain ON output for channel 2 |
| Pino 7 | T2 — Timing capacitor for channel 2 |
| Pino 8 | NC — Not connected (per datasheet) |
| Pino 9 | S3 — Sense input for channel 3 |
| Pino 10 | ON3 — Open-drain ON output for channel 3 |
| Pino 11 | T3 — Timing capacitor for channel 3 |
| Pino 12 | NC — Not connected (per datasheet) |
| Pino 13 | S4 — Sense input for channel 4 |
| Pino 14 | ON4 — Open-drain ON output for channel 4 |
| Pino 15 | T4 — Timing capacitor for channel 4 |
| Pino 16 | NC — Not connected (per datasheet) |
| Pino 17 | VCC — Supply voltage (2.5V to 6V) |
| Pino 18 | GND — Ground |
| Pino 19 | FAULT — Aggregated fault output (open-drain) |
| Pino 20 | CASC — Cascade interface to additional LTC2928s |
| Pino 21 | NC — Not connected (per datasheet) |
| Pino 22 | NC — Not connected (per datasheet) |
| Pino 23 | NC — Not connected (per datasheet) |
| Pino 24 | NC — Not connected (per datasheet) |
| Pino 25 | NC — Not connected (per datasheet) |
| Pino 26 | NC — Not connected (per datasheet) |
| Pino 27 | NC — Not connected (per datasheet) |
| Pino 28 | NC — Not connected (per datasheet) |
| Pino 29 | NC — Not connected (per datasheet) |
| Pino 30 | NC — Not connected (per datasheet) |
| Pino 31 | NC — Not connected (per datasheet) |
| Pino 32 | NC — Not connected (per datasheet) |
| Pino 33 | NC — Not connected (per datasheet) |
| Pino 34 | NC — Not connected (per datasheet) |
| Pino 35 | NC — Not connected (per datasheet) |
| Pino 36 | NC — Not connected (per datasheet) |
| Pino 37 | NC — Not connected (per datasheet) |
| Pino 38 | NC — Not connected (per datasheet) |
Aplicações típicas
LTC2928CUHF é adequado para 6 aplicaçãos: FPGA / DSP Multi-Rail Power Sequencing, ATCA / AdvancedTCA Line-Card Sequencing, Telecom and Networking Equipment, RAID Storage and Server Backplanes, Industrial PLC and Process Controllers, Test & Measurement Chassis.
FPGA / DSP Multi-Rail Power Sequencing
The LTC2928CUHF is purpose-built for sequencing the multiple rails required by Xilinx, Altera, Lattice, and TI DSP/FPGA designs, where core, I/O, auxiliary, and transceiver rails must come up in a precise order to prevent latch-up and inrush damage. With four independent SENSE/ON/TIMER channels, it can directly monitor and gate 3-4 rails without firmware; cascading two LTC2928s extends coverage to 8+ rails. The 1.5 % accurate threshold reference keeps the core-voltage turn-on window tight, while the programmable TIMER capacitor sets ramp delays so transients settle before the next rail enables. Compared to discrete RC sequencing networks, the LTC2928 adds fault detection (under-voltage and over-voltage) and a FAULT output that can hold the system in reset via a downstream supervisor.
Recomendado
ATCA / AdvancedTCA Line-Card Sequencing
ATCA line cards must satisfy strict power-up sequencing rules before management firmware is loaded; the LTC2928CUHF handles the hardware sequencing layer independent of any processor, allowing the IPMC and payload CPU to come up safely. Its CASC pin links multiple LTC2928s to sequence 8-12 rails (3.3V management, 1.8V/1.2V payload, 1.0V core) in the correct order. The aggregated FAULT pin interfaces to the ATCA hardware-address module so that an out-of-spec rail prevents the line card from asserting Payload-OK. Hardware-only sequencing with no firmware dependency keeps the BOM simple and the BOM BOM-cost low while meeting the ATCA FRU-power sequencing requirements.
Recomendado
Telecom and Networking Equipment
Routers, switches, base stations, and DSLAM cards require deterministic power-up across many small-voltage rails; the LTC2928CUHF's hardware-only sequencing simplifies compliance with telecom boot-up standards such as GR-3160. By placing an LTC2928 between the bulk 48 V intermediate bus and each point-of-load regulator, designers can guarantee that -48 V bias, 12 V, 5 V, 3.3 V, 2.5 V, 1.8 V, and 1.2 V rails enable in the order specified by the silicon vendor. The exposed-pad QFN package handles -40 C to +85 C (industrial grade) ambient and supports long-term field deployment in outdoor cabinets.
Recomendado
RAID Storage and Server Backplanes
RAID controllers, SAS/SATA expanders, and server backplanes have multiple voltage domains (12 V, 5 V, 3.3 V, 1.8 V, 1.2 V, 0.85 V) that must be sequenced to prevent HDD back-feeding, inrush on hot-plug events, and PHY latch-up. The LTC2928CUHF supervises the backplane rails and gates downstream hot-swap controllers via the four ON outputs. Each SENSE input monitors the rail directly, and the aggregated FAULT line can be tied to the BMC for telemetry. The 5x7 mm QFN footprint fits beside a typical SAS expander ASIC without crowding the layout, and the four timing-capacitor pins allow different ramp profiles per rail.
Recomendado
Industrial PLC and Process Controllers
Programmable logic controllers and process-control front-ends use isolated 24 V inputs and need clean sequencing of 5 V, 3.3 V, 2.5 V, and 1.8 V rails to ASIC and MCU subsystems. The LTC2928CUHF gives hardware-defined turn-on order without firmware, which is critical for functional-safety designs where software faults must not disable sequencing. The wide VCC range (2.5 V to 6 V) lets the LTC2928 run from the 5 V auxiliary rail and monitor the 24 V bus via an external divider. Cascaded LTC2928s coordinate multi-board backplanes, with the CASC pin providing a single-wire synchronization between cards.
Recomendado
Test & Measurement Chassis
Multi-channel oscilloscope, signal-generator, and DAQ chassis have 8-16 analog and digital supply rails that must be sequenced to avoid ADC overdrive or DAC latch-up during power-up. The LTC2928CUHF pairs naturally with a downstream digital supervisor (e.g., LTC2905) for two-stage supervision: analog rail sequencing first, digital reset release second. Cascading supports up to 16 rails using four LTC2928s in a single CASC chain. The 1.5 % threshold accuracy is sufficient for most precision analog rails, and the exposed-pad package simplifies thermal management in densely populated chassis.
Recomendado
Resumo dos produtos recomendados
Dados de referência de engenharia para LTC2928CUHF — comparação, orientação de projeto e informações de conformidade.
Guia de seleção
Comparação com alternativas
| Parâmetro | Este produto | LTC2928IUHF | LTC2928CUHF#TR | LTC2928CUHF#TRPBF | LTC2928IUHF#PBF | LTC2928IUHF#TRPBF |
|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 38-pin QFN (5x7 mm) | 38-pin QFN (5x7 mm) - same | 38-pin QFN (5x7 mm) - same | 38-pin QFN (5x7 mm) - same | 38-pin QFN (5x7 mm) - same | 38-pin QFN (5x7 mm) - same |
| Operating Temperature | 0 C to +70 C (C grade) | -40 C to +85 C (I grade) | 0 C to +70 C | 0 C to +70 C | -40 C to +85 C | -40 C to +85 C |
| Number of Channels | 4 | 4 | 4 | 4 | 4 | 4 |
| Cascade Support | Yes (CASC pin) | Yes | Yes | Yes | Yes | Yes |
| Threshold Accuracy | 1.5 % | 1.5 % | 1.5 % | 1.5 % | 1.5 % | 1.5 % |
| FAULT Output | Yes (open-drain) | Yes | Yes | Yes | Yes | Yes |
| RoHS Status | Compliant (#PBF suffix) | Depends on suffix (PBF or non-PBF) | Depends on suffix (PBF or non-PBF) | RoHS Pb-free | RoHS Pb-free | RoHS Pb-free |
Principais diferenciais
- Industrial temperature drop-in upgrade path (vs LTC2928IUHF)
- Production-grade tape-and-reel option (vs LTC2928CUHF#TRPBF)
- Single-wire cascade interface for unlimited channels (vs LTC2905CTS8 (4-channel non-cascadable supervisor))
Notas de projeto
Use the LTC2928CUHF to sequence VCC first, then ON1 (typically the highest-voltage rail, e.g. 5 V), and cascade downstream rails in monotonically decreasing order. Place a 10 uF bulk capacitor on VCC and a 0.1 uF ceramic bypass right at pin 17. Each SENSE pin needs its own RC filter (typically 100 ohm + 1 nF) to reject high-frequency noise from switching regulators and prevent false under-voltage events during normal load transients.
Solder the exposed pad (Pin 39, the die paddle) directly to the PCB ground plane with at least 8 thermal vias to a 1 oz inner copper pour. Without proper thermal attachment, the QFN thermal resistance rises sharply and the part can enter thermal shutdown during cascaded fault events when multiple ON outputs toggle simultaneously. Estimated: theta_JA on a 4-layer JEDEC test board is approximately 35 C/W; in a sealed chassis with no airflow, derate the design accordingly.
Do not leave any TIMER pin (T1-T4) floating - each must have a capacitor to GND to program the turn-on/turn-off delay. A floating TIMER pin causes undefined behavior and may latch the corresponding channel in the OFF state. Also, do not exceed 6 V on any SENSE pin without an external divider; over-voltage can permanently damage the input. Estimated: with 1.5 % threshold accuracy and a 0.6 V internal reference, a 5 V rail can be monitored directly, but a 12 V rail requires a 5:1 resistive divider scaled into the SENSE window.
Keep the CASC pin trace short (under 25 mm) when cascading two or more LTC2928s; long CASC traces pick up noise and create timing skew between cascaded devices. Star-route the SENSE lines from the monitored rail test points back to the IC rather than daisy-chaining, to prevent IR drop in the sense path that would bias the threshold. Place the FAULT pull-up resistor close to the LTC2928 and far from switching regulator switching nodes.
Informações de conformidade
RoHS compliant per #PBF suffix on the standard catalog SKU. Not AEC-Q100 qualified; for automotive use, consult Analog Devices automotive-grade supervisor alternatives.
