LTC7802JUFDM#WPBF - 40V Low IQ Dual Step-Down Controller | ADI
MPN： LTC7802JUFDM#WPBF ✓ 啟用中LTC7802JUFDM#WPBF 概覽
A step-down synchronous DC/DC switching controller is a semiconductor that regulates an output voltage by rapidly switching a pair of MOSFETs between charging and discharging an inductor. Compared with linear regulators, switching controllers achieve high efficiency across wide VIN/VOUT ratios, placing them at the heart of the power management IC hierarchy: switching controller -> DC-DC converter -> voltage regulator -> power management IC. The LTC7802 family adds low-IQ Burst Mode operation, extending the family lineage from earlier ADI controllers such as the LTC3866 and LTC3897.
Key features include 99% maximum duty cycle for low dropout, internal top and bottom N-channel MOSFET drivers, an internal 100 kohm MODE pin pull-down for default Burst Mode operation, an EXTVcc LDO for driver supply, and per-channel PGOOD indicators. A precision 0.8V reference and selectable light-load modes (Burst Mode, pulse-skip, or forced continuous current) enable designers to optimize efficiency versus output ripple. Spread-spectrum frequency modulation is selectable via the PLLIN/SPREAD pin to ease EMI compliance in automotive and industrial systems.
The LTC7802 uses a peak current-mode architecture with cycle-by-cycle current limiting and a phase-locked loop that synchronizes to an external clock between 100 kHz and 3 MHz. The 2-phase current-sharing topology doubles the effective ripple frequency at the input capacitor, reducing input ripple voltage by up to 50% versus a single-phase design. Internal bootstrap switches eliminate external Schottky diodes, while the high-side gate drivers tolerate 40V abs-max VSW transients. The result is a flexible controller family suitable for automotive 12V/24V systems, industrial 24V buses, battery-powered portable equipment, and high-current point-of-load rails.
Typical applications include dual-output telecom and networking infrastructure supplies, automotive ECU and infotainment power rails, industrial 24V PLC and motor-control auxiliaries, battery-powered portable instruments, and low-noise FPGA/ASIC multi-rail power. The wide input range and 2-phase capability suit high-current point-of-load converters feeding ASICs and FPGAs that demand both efficiency and low EMI.
When designing, derate the junction temperature for the 28-QFN-EP 4x5 mm package using the manufacturer-specified theta_JA value and provide at least four thermal vias under the exposed pad. A minimum of 1 uF of low-ESR ceramic input capacitance per phase plus 22 uF bulk capacitance is recommended to keep input ripple below 50 mVpk-pk in 2-phase operation.
This page synthesizes distributor pricing, parametric cross-reference data, and application design notes not found in the manufacturer datasheet, giving engineers a one-stop alternative selection and design reference for the LTC7802JUFDM#WPBF.
直接替換替代品，適用於 LTC7802JUFDM#WPBF — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： LTC7802JUFDM#WPBF （相同外形與佔位） — 差異在於 Number of Outputs, Output Voltage Range, Package, RoHS Status, Topology.
LTC7802HUFDM#WPBF
✅ 直接替換📋 參考替代品（不在目錄中）
LTC7802EUFDM#WPBF
✅ 直接替換📋 參考替代品（不在目錄中）
LTC7802JUFDM-3.3#WPBF
✅ 直接替換📋 參考替代品（不在目錄中）
LTC3899EFE
✅ 直接替換聯絡詢價
查看資料表 →LTC7802JUFDM#WPBF 最大額定值與電氣特性
| 拓撲 | Dual synchronous buck controller |
| 輸出數量 | 2 |
| 輸入電壓範圍 | 4.5 V to 40 V |
| 輸出電壓範圍 | 0.8 V to VIN (min 0.8 V) |
| Output Current | Dependent on external MOSFETs |
| Switching Frequency Range | 100 kHz to 3 MHz (PLL-lockable) |
| Maximum Duty Cycle | 99 % |
| Feedback Voltage Accuracy | ±1 % over temperature |
| 參考電壓 | 0.8 V |
| 工作溫度範圍 | -40 C to +150 C (TJ) |
| 封裝 | 28-lead QFN (4x5 mm) with exposed pad |
| RoHS 狀態 | Compliant |
| Lead-Free | Yes |
| Wettable Flanks | Yes (UFDM suffix) |
| Spread-Spectrum Modulation | Selectable via PLLIN/SPREAD pin |
LTC7802JUFDM#WPBF 腳位配置
| 腳位 1 | VIN — Main input supply (4.5V to 40V) |
| 腳位 2 | INTVDD — Internal 5V LDO output for gate drivers |
| 腳位 3 | EXTVCC — External driver supply input (optional bypass of INTVDD) |
| 腳位 4 | BG1 — Channel 1 bottom-gate driver output |
| 腳位 5 | TG1 — Channel 1 top-gate driver output |
| 腳位 6 | BOOST1 — Channel 1 bootstrap capacitor node |
| 腳位 7 | SW1 — Channel 1 switching node |
| 腳位 8 | SENSE1+ — Channel 1 current-sense positive input |
| 腳位 9 | SENSE1- — Channel 1 current-sense negative input |
| 腳位 10 | VFB1 — Channel 1 voltage feedback (0.8V ref) |
| 腳位 11 | ITH1 — Channel 1 error-amplifier compensation node |
| 腳位 12 | PGOOD1 — Channel 1 power-good open-drain output |
| 腳位 13 | RUN1 — Channel 1 enable (active high) |
| 腳位 14 | PGND — Power ground |
| 腳位 15 | RUN2 — Channel 2 enable (active high) |
| 腳位 16 | PGOOD2 — Channel 2 power-good open-drain output |
| 腳位 17 | ITH2 — Channel 2 error-amplifier compensation node |
| 腳位 18 | VFB2 — Channel 2 voltage feedback (0.8V ref) |
| 腳位 19 | SENSE2- — Channel 2 current-sense negative input |
| 腳位 20 | SENSE2+ — Channel 2 current-sense positive input |
| 腳位 21 | SW2 — Channel 2 switching node |
| 腳位 22 | BOOST2 — Channel 2 bootstrap capacitor node |
| 腳位 23 | TG2 — Channel 2 top-gate driver output |
| 腳位 24 | BG2 — Channel 2 bottom-gate driver output |
| 腳位 25 | SGND — Signal ground |
| 腳位 26 | MODE — Light-load mode select (Burst/pulse-skip/forced continuous) |
| 腳位 27 | PLLIN/SPREAD — External clock sync / spread-spectrum enable |
| 腳位 28 | FREQ/SS — Frequency set / soft-start programming |
典型應用
LTC7802JUFDM#WPBF 適用於 6 應用s: Automotive 12V/24V ECU Power, Industrial 24V PLC and Motor Control, Telecom and Networking Infrastructure, Battery-Powered Portable Equipment, FPGA/ASIC Multi-Rail Point-of-Load, Medical Patient Monitoring Devices.
Automotive 12V/24V ECU Power
The LTC7802JUFDM#WPBF is well-suited to automotive ECU power rails because its 40V abs-max input tolerates 24V truck bus transients and load-dump pulses up to 35V. The 2-phase current sharing halves input ripple for downstream ASICs, while spread-spectrum modulation eases conducted EMI compliance against CISPR 25. The wettable-flank QFN package supports AOI inspection mandated by automotive PCBA lines, and the J-grade -40 C to +150 C rating covers underhood and dashboard environments.
推薦
Industrial 24V PLC and Motor Control
In industrial 24V PLC and motor-control auxiliaries, the LTC7802JUFDM#WPBF supplies logic rails and gate-driver supplies from a wide 4.5V to 40V bus. Its 99% maximum duty cycle holds regulation through input voltage sags during motor inrush events, and the 3 MHz switching capability allows use of small ceramic output capacitors. Two independent outputs let one IC generate 5V and 3.3V rails directly from the 24V backplane, reducing BOM count and PCB area by ~30% versus two single-phase controllers.
推薦
Telecom and Networking Infrastructure
For telecom and networking infrastructure, the LTC7802JUFDM#WPBF powers PoE and line-card subsystems from -48V telecom rails stepped down to 12V and 5V with the help of an upstream front-end converter. The PLL-lockable oscillator synchronizes to system clocks, eliminating beat-frequency interference between rails. Burst Mode operation reduces quiescent current during light-load standby, helping meet energy-efficiency targets like ATIS-0600315 and 80 PLUS compliance for the host equipment.
推薦
Battery-Powered Portable Equipment
Battery-powered portable instruments benefit from the LTC7802JUFDM#WPBF's Burst Mode operation, which drops quiescent current into the microamp range between load events, extending battery runtime. The wide 4.5V to 40V input lets designers accept multi-cell lithium packs up to 12S (50.4V full charge) without front-end protection. Two independent rails feed the analog front end and the digital MCU from a single IC, shrinking PCB footprint by up to 40% versus two discrete controllers.
推薦
FPGA/ASIC Multi-Rail Point-of-Load
FPGAs and ASICs typically require 0.85V core, 1.2V DDR, and 1.8V I/O rails, all of which the LTC7802JUFDM#WPBF can supply as dual outputs with the help of an external LDO post-regulator for the lowest-noise rail. 2-phase operation reduces input ripple voltage below 30 mVpk-pk, supporting sensitive SERDES and ADC reference rails without dedicated filtering. The 3 MHz switching keeps the converter above the AM band, simplifying EMI certification for the host system.
推薦
Medical Patient Monitoring Devices
Patient monitors demand clean, low-EMI rails for ADCs and signal-acquisition front ends. The LTC7802JUFDM#WPBF's spread-spectrum option reduces peak EMI emissions to meet IEC 60601-1-2 medical EMC limits, while the 0.8V precision reference and ±1% feedback accuracy support ADC reference-voltage accuracy chains. The dual-output topology lets one IC generate the isolated-side logic and analog rails, halving PCB area and BOM cost versus two single-phase controllers in space-constrained bedside monitor enclosures.
推薦
推薦產品摘要
工程參考資料，適用於 LTC7802JUFDM#WPBF — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | LTC7802HUFDM#WPBF | LTC7802EUFDM#WPBF | LTC7802JUFDM-3.3#WPBF | LTC3899EFE |
|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 28-QFN-EP (4x5 mm) | 28-QFN-EP (4x5 mm) - same | 28-QFN-EP (4x5 mm) - same | 28-QFN-EP (4x5 mm) - same | TSSOP-38-EP - different footprint |
| Input Voltage Range | 4.5 V to 40 V | 4.5 V to 40 V | 4.5 V to 40 V | 4.5 V to 40 V | 4.5 V to 40 V |
| Switching Frequency (max) | 3 MHz | 3 MHz | 3 MHz | 3 MHz | 3 MHz |
| Temperature Grade | J (-40 C to +150 C) | H (-40 C to +150 C extended) | E (-40 C to +85 C) | J (-40 C to +150 C) | E (-40 C to +85 C) |
| Reference Voltage | 0.8 V adjustable | 0.8 V adjustable | 0.8 V adjustable | 3.3 V fixed on CH1 | 0.8 V adjustable |
| Maximum Duty Cycle | 99 % | 99 % | 99 % | 99 % | 99 % |
| Spread-Spectrum Modulation | Selectable | Selectable | Selectable | Selectable | Selectable |
主要差異化特點
- Smallest 4x5 mm 28-QFN-EP footprint with wettable flanks for automotive AOI (對比LTC3899EFE)
- J-grade 150 C junction rating for harsh environments (對比LTC7802EUFDM#WPBF)
- Adjustable 0.8V reference for full design flexibility (對比LTC7802JUFDM-3.3#WPBF)
設計說明
Estimated: the 28-QFN-EP 4x5 mm package with the exposed pad soldered to 1 square inch of 2 oz copper on a 4-layer PCB typically achieves theta_JA in the 30-35 C/W range. At 1 A load per channel, 12V input, and 5V output, per-channel dissipation is about 7 W (P = (VIN-VOUT) * IOUT * (1 - efficiency)), so two channels sum to ~14 W. Estimate junction temperature rise at ~14 W * 32 C/W = 448 C above ambient, meaning a heatsink or substantial copper area is required to keep TJ below 150 C.
Place input ceramic bypass capacitors (1 uF X7R minimum) within 5 mm of the VIN pin and PGND pin to suppress switching spikes. The exposed pad must be soldered to a continuous ground plane with at least 4 thermal vias (0.3 mm drill, 1 oz plating) connecting the top pad to inner ground planes for heat sinking. Keep the SW1 and SW2 nodes short to minimize EMI radiation; route feedback traces away from switching nodes to avoid noise coupling into the VFB pins.
Do not float the MODE pin: it has an internal 100 kohm pull-down that defaults to Burst Mode operation but may behave unpredictably on noisy boards. Tie MODE to SGND for Burst Mode, to INTVDD for forced continuous mode, or through a 100 kohm resistor to select pulse-skipping mode. Similarly, do not leave RUN1 or RUN2 floating - the controller requires a positive logic signal above 1.2V to enable, and floating pins may cause intermittent start-up failures in production.
Enable spread-spectrum modulation by tying PLLIN/SPREAD to SGND for ~25% frequency dithering, which spreads peak EMI emissions across a 750 kHz window and typically reduces conducted EMI by 6-10 dB at the fundamental switching frequency. For additional EMI margin, add a small ferrite bead (600 ohm at 100 MHz) on the input supply line and place a 4.7 uF X7R capacitor across the VIN-PGND pair near the IC. These measures together typically bring the design below CISPR 25 Class 5 limits without a pi-filter.
合規資訊
RoHS and REACH compliant per Analog Devices product page. AEC-Q100 status not explicitly stated for this commercial/industrial J-grade variant; ADI offers separate automotive-grade parts in this family. Lead-free terminations confirmed.
