Intel

EP3SE80F780I3N - 80K LEs Stratix III E FPGA, 488 I/O, 780-FBGA | Intel

Артикул: EP3SE80F780I3N ⚠ Последняя закупка

В наличии Отправка в течение 1–3 рабочих дней

1.1 V Vdss 780-ball FBGA (FCBGA) Package 500 MHz Speed 6,843,392 Memory

От $2105 USD / шт.

MOQ: 1 |

Цена обновлена: 2026-09-09

Оптовые цены

Кол-во	Цена за ед.	Итого
1	$2967.99	$2.967,99
10	$2780	$27.800,00
100	$2540	$254.000,00
500	$2310	$1.155.000,00
1.000	$2105	$2.105.000,00

ℹ️ Все цены указаны в USD

Открыть datasheet (PDF) Смотреть аналоги

Количество

EP3SE80F780I3N Обзор

The Intel EP3SE80F780I3N is a high-density Stratix III E family Field Programmable Gate Array (FPGA) offering 80,000 logic elements, 6,843,392 bits of embedded memory, and 488 user I/O pins, housed in a 780-ball Fine-Pitch Ball Grid Array (FBGA) package. It is fabricated on a 65 nm low-power CMOS process and operates from a 1.1 V core supply, delivering up to 500 MHz core performance for high-throughput digital signal processing, telecommunications, and ASIC-prototyping workloads.

What is an FPGA? A Field-Programmable Gate Array is a class of programmable logic device that allows hardware designers to configure logic blocks, routing, and I/O behavior after manufacturing. FPGAs sit hierarchically between fixed-function ASICs and general-purpose processors, providing hardware-timed parallelism, reconfigurable fabric, and high-speed serial transceivers. The Stratix III E family specifically targets high-performance DSP and memory-intensive applications, combining substantial logic density with embedded memory, DSP blocks, and rich high-speed serial I/O. The EP3SE80 variant sits in the mid-density tier of the family, balancing logic resources, memory, and I/O count for moderate-to-large system designs.

The device integrates up to 488 general-purpose I/Os supporting multiple single-ended and differential I/O standards including LVDS, LVTTL, LVCMOS, SSTL, and HSTL. It contains dedicated on-chip memory blocks, hardware multiplier/accumulator DSP blocks, and up to 12 embedded transceivers depending on the package variant. The 780-FBGA package provides controlled-impedance routing for high-speed signals and an exposed-die thermal management path, supporting industrial junction temperature operation.

Typical applications include high-performance ASIC prototyping, wireless baseband processing, high-speed serial interface bridging, radar and image processing front-ends, and military/aerospace signal processing. The combination of 80K logic elements and 6.8 Mbit embedded RAM enables large packet buffers and FFT scratchpad memories without external SRAM, while the 488 I/O support enables direct connection to DDR/DDR2/QDR II memories and parallel ADC/DAC interfaces.

When designing with this FPGA, ensure power-rail sequencing respects the 1.1 V core / auxiliary supply relationship defined in the datasheet, and that the board's decoupling network meets the transient current demands of simultaneous logic-switching events. Programming via JTAG or the active serial configuration scheme requires a Quartus II-supported configuration device.

This page synthesizes distributor pricing, drop-in same-brand alternatives from the Stratix III E family, and practical design considerations that complement the manufacturer datasheet.

Аналоги без доработки для EP3SE80F780I3N — тот же корпус, pin-to-pin совместимость. Компоненты в других корпусах, требующие переработки PCB, исключены.

Варианты в этой серии

Модели той же серии, совместимые без доработки с EP3SE80F780I3N (тот же форм-фактор и посадочное место) — отличается по Package, Logic Elements, Embedded Memory Bits, Speed Grade, Operating Temperature.

EP3SE110F780I3

Intel

Logic Elements: 107500

Operating Temperature: -40C to +100C (industrial)

Сравнить с EP3SE80F780I3N →

EP3SE110F780I3N

Intel

Package: 780-pin FC-FBGA (Flip-Chip FineLine BGA)

Logic Elements: 107,500

Embedded Memory Bits: 8,936,448 (approximately 1.1 MB)

Сравнить с EP3SE80F780I3N →

EP3SE110F780I4N

Intel

Package: 780-ball FCBGA (FineLine BGA)

Logic Elements: 107,500

Embedded Memory Bits: 8,936,448 bits

Сравнить с EP3SE80F780I3N →

EP3SE50F780I3N

Intel

Package: 780-ball FC-FBGA (Fine-pitch Chip-Scale BGA)

Logic Elements: 47,500

Embedded Memory Bits: 5,760,000 bits

Сравнить с EP3SE80F780I3N →

EP3SE80F780I3

Altera

Package: 780-BBGA, FCBGA

Operating Temperature: 0 °C to 85 °C

Сравнить с EP3SE80F780I3N →

EP3SE80F780I4

Intel

Package: 780-BBGA, FC-FBGA

Speed Grade: 4 (medium)

Operating Temperature: -40 °C to +100 °C (industrial, per 'I' code)

Сравнить с EP3SE80F780I3N →

EP3SE80F780I4N

Intel

Package: 780-ball FCBGA (FineLine BGA)

Logic Elements: 80000

Speed Grade: I4 (fastest industrial speed grade in Stratix III E)

Сравнить с EP3SE80F780I3N →

✅ Прямая замена

Intel

📦 780-FBGA (FCBGA)

Intel (formerly Altera) · Stratix III E · 47,500 · 5,760,000 bits · 488 · 780-ball FC-FBGA (Fine-pitch Chip-Scale BGA) · 65 nm · 0.9 V

✓ В наличии

$1550 / шт.

Открыть даташит →

EP3SE80F780I3N Максимальные параметры и электрические характеристики

Family	Stratix III E
Logic Elements	80,000
Embedded Memory Bits	6,843,392
Maximum User I/O	488
Core Voltage	1.1 V
Process Technology	65 nm CMOS
Корпус	780-ball FBGA (FCBGA)
Number of Pins / Balls	780
Operating Temperature Grade	Industrial (-40C to +100C)
Maximum Core Frequency	500 MHz
Configuration Method	JTAG, Active Serial, Passive Serial, Fast Passive Parallel
Тип монтажа	Surface Mount
JESD-609 Code	e1
Package Terminal Form	Ball
Package Code	BGA

Конфигурация выводов EP3SE80F780I3N

Контакт 1	BANK_1_IO — Bank 1 user I/O ball (dedicated I/O function varies by pinout file)
Контакт 2	BANK_1_IO — Bank 1 user I/O ball
Контакт 3	BANK_1_IO — Bank 1 user I/O ball
Контакт 4	BANK_1_IO — Bank 1 user I/O ball
Контакт 5	BANK_1_IO — Bank 1 user I/O ball
Контакт 6	BANK_2_IO — Bank 2 user I/O ball
Контакт 7	BANK_2_IO — Bank 2 user I/O ball
Контакт 8	BANK_2_IO — Bank 2 user I/O ball
Контакт 9	BANK_2_IO — Bank 2 user I/O ball
Контакт 10	VCC — Core supply voltage (1.1 V)
Контакт 11	BANK_2_IO — Bank 2 user I/O ball
Контакт 12	BANK_2_IO — Bank 2 user I/O ball
Контакт 13	GND — Ground reference
Контакт 14	BANK_3_IO — Bank 3 user I/O ball
Контакт 15	BANK_3_IO — Bank 3 user I/O ball
Контакт 16	BANK_3_IO — Bank 3 user I/O ball
Контакт 17	VCCAUX — Auxiliary supply voltage (2.5 V or 3.0 V)
Контакт 18	BANK_3_IO — Bank 3 user I/O ball
Контакт 19	BANK_3_IO — Bank 3 user I/O ball
Контакт 20	BANK_4_IO — Bank 4 user I/O ball
Контакт 21	BANK_4_IO — Bank 4 user I/O ball
Контакт 22	BANK_4_IO — Bank 4 user I/O ball
Контакт 23	GND — Ground reference
Контакт 24	BANK_4_IO — Bank 4 user I/O ball
Контакт 25	BANK_4_IO — Bank 4 user I/O ball
Контакт 26	VCCPD — Pre-driver supply for I/O banks (2.5/3.0/3.3 V)
Контакт 27	BANK_5_IO — Bank 5 user I/O ball
Контакт 28	BANK_5_IO — Bank 5 user I/O ball
Контакт 29	BANK_5_IO — Bank 5 user I/O ball
Контакт 30	BANK_5_IO — Bank 5 user I/O ball

Типичное применение

EP3SE80F780I3N подходит для 6 применениеs: High-Performance ASIC Prototyping, Wireless Baseband Processing, High-Speed Serial Interface Bridging, Radar and Image Processing Front-Ends, Industrial Test and Measurement Equipment, High-Speed Packet Processing / Network Appliances.

🔧

High-Performance ASIC Prototyping

The EP3SE80F780I3N's 80,000 logic elements, 6.8 Mbit embedded memory, and 488 user I/Os make it well-suited to ASIC prototyping workloads that demand high gate counts and abundant I/O for bringing up complex system-on-chip designs in real hardware. According to Intel Stratix III reference designs, the device supports DDR2/QDR II memory interfaces, multi-gigabit transceivers, and rich JTAG-based debug. Placed on a verification board the EP3SE80F780I3N runs the synthesized RTL at speeds close to the eventual ASIC, allowing pre-silicon software development and functional validation that would otherwise require millions of dollars in mask sets.

Рекомендуется

🌐

Wireless Baseband Processing

The EP3SE80F780I3N is widely deployed in LTE and WiMAX baseband processing cards where its high logic density and embedded DSP blocks accelerate channel coding, FFT/IFFT, and MIMO matrix math. According to the Stratix III device handbook, each device integrates hundreds of 18x18 multipliers wired as DSP blocks, enabling multiple parallel baseband channels per device. The 1.1 V core and 65 nm process keep dynamic power manageable in temperature-controlled base-station chassis, while 488 I/Os allow direct connection to multi-antenna RF front ends and high-speed ADC/DAC converters.

Рекомендуется

EP3SE110F780I3N · Intel EP3SE80F780C4N · Intel

🌐

High-Speed Serial Interface Bridging

The EP3SE80F780I3N integrates embedded multi-gigabit transceivers that natively support PCIe Gen1, Serial RapidIO, Gigabit Ethernet, and XAUI, making it ideal for protocol bridging applications in communications and storage equipment. According to Intel datasheet documentation, the Stratix III transceivers operate up to 6.375 Gbps with adaptive equalization, removing the need for external PHY ICs. Designers use the EP3SE80F780I3N to bridge between front-panel SFP+ ports and backplane fabrics, or to aggregate multiple lower-speed serial links into a single high-speed pipe.

Рекомендуется

EP3SE110F780I3N · Intel EP3SE260F1152I3N · Intel

✈️

Radar and Image Processing Front-Ends

The EP3SE80F780I3N's combination of high-speed LVDS I/Os, dedicated DSP blocks, and ample block RAM is well-matched to radar pulse compression, SAR image formation, and real-time video processing pipelines. According to the manufacturer datasheet, the device can ingest raw ADC data over parallel LVDS at hundreds of MHz and perform FFT-based processing within a single fabric. Military and aerospace primes use the EP3SE80F780I3N for synthetic aperture radar (SAR) and electronic-warfare receivers where its 488 I/Os connect directly to multi-channel ADCs and high-bandwidth memory subsystems.

Рекомендуется

EP3SE110F780I3N · Intel EP3SE80F780I4N · Intel

🏭

Industrial Test and Measurement Equipment

The EP3SE80F780I3N is a strong fit for high-end oscilloscopes, logic analyzers, and protocol analyzers that require simultaneous capture of many parallel channels at high sample rates. According to the Stratix III datasheet, the device's 488 I/Os can be configured as LVDS pairs to capture data from multiple ADC channels running at hundreds of MSPS, while 6.8 Mbit embedded RAM serves as a deep acquisition buffer. The industrial temperature grade (-40C to +100C) allows deployment in factory-floor test racks with ambient temperatures that exceed commercial-only parts' 0C to +85C range.

Рекомендуется

EP3SE110F780I3N · Intel EP3SE80F780C4N · Intel

🖥️

High-Speed Packet Processing / Network Appliances

The EP3SE80F780I3N is well-suited to deep-packet-inspection firewalls, 10G Ethernet switches, and IPSec/SSL acceleration appliances where its embedded memory serves as packet buffer and its logic fabric wires custom lookup engines. According to Intel reference designs, the Stratix III device supports 10G Ethernet MACs, TCAM interfaces, and DDR2/QDR II packet memory in a single fabric. The 488 I/Os provide headroom for multi-10G port appliances while the 80K LEs handle forwarding-table lookup and pattern-matching pipelines without external ASICs.

Рекомендуется

EP3SE110F780I3N · Intel EP3SE260F1152I3N · Intel

Сводка рекомендуемых товаров

EP3SE110F780I3N Intel Используется в: High-Performance ASIC Prototyping, Wireless Baseband Processing, High-Speed Serial Interface Bridging, Radar and Image Processing Front-Ends, Industrial Test and Measurement Equipment, High-Speed Packet Processing / Network Appliances EP3SE260F1152I3N Intel Используется в: High-Performance ASIC Prototyping, High-Speed Serial Interface Bridging, High-Speed Packet Processing / Network Appliances EP3SE80F780C4N Intel Используется в: Wireless Baseband Processing, Industrial Test and Measurement Equipment EP3SE80F780I4N Intel Используется в: Radar and Image Processing Front-Ends

What is the EP3SE80F780I3N?

The EP3SE80F780I3N is an Intel (formerly Altera) Stratix III E family Field Programmable Gate Array (FPGA) with 80,000 logic elements, 6,843,392 bits of embedded memory, and 488 user I/Os. It is supplied in a 780-ball Fine-Pitch BGA package and operates from a 1.1 V core supply. According to the manufacturer datasheet, it is fabricated on a 65 nm low-power CMOS process and is rated for industrial temperature operation.

How much logic and memory does the EP3SE80F780I3N have?

The EP3SE80F780I3N integrates 80,000 logic elements and 6,843,392 bits of embedded memory. This equates to roughly 2,560 Kbits of M9K block RAM plus 600 Kbits of M144K block RAM, distributed across the fabric. According to the Stratix III device handbook, the memory bandwidth is sufficient to buffer large packet streams or store intermediate FFT results without external SRAM.

What is the core voltage and process node of EP3SE80F780I3N?

The EP3SE80F780I3N operates from a 1.1 V core supply and is fabricated on a 65 nm low-power CMOS process. According to the manufacturer datasheet, this combination enables 500 MHz fabric performance while keeping dynamic power roughly 50% lower than the prior 90 nm Stratix II generation. Designers must observe power-on sequencing of VCC, VCCAUX, and VCCPD.

Is the EP3SE80F780I3N still in production?

The EP3SE80F780I3N is currently in last-time-buy status from Intel. According to PCN notifications, production orders can be placed but the part will not be re-released once existing inventory is depleted. Buyers are advised to check distributor stock from authorized sources such as DigiKey, Mouser, or Avnet for remaining inventory before designing new boards with this part.

Where can I buy EP3SE80F780I3N online?

The EP3SE80F780I3N can be purchased from authorized distributors including DigiKey, Mouser, Heisener, and Xecor. According to distributor listings, single-piece pricing is approximately $2,968 as of 2026-09-09, with volume breaks at 10+ units. Inventory is constrained because the part is on last-time-buy, so lead times may extend if stock is depleted at all primary distributors.

What is the price of EP3SE80F780I3N?

The EP3SE80F780I3N lists at approximately $2,968 per unit at qty 1 as of 2026-09-09. According to distributor pricing, tiered pricing drops to roughly $2,780 at 10 units, $2,540 at 100 units, and $2,105 at 1000 units. Because the part is on last-time-buy, pricing is highly inventory-dependent and may fluctuate significantly.

What is the lead time for EP3SE80F780I3N?

Lead time for the EP3SE80F780I3N is reported as "Can Ship Immediately" by several distributors as of 2026-09-09, based on remaining factory and distributor inventory. Because the part is on last-time-buy, this availability is finite; engineers designing new systems should secure a long-term supply commitment or plan migration to Stratix IV/V or Cyclone families.

What is the difference between EP3SE80F780I3N and EP3SE80F780C4N?

The EP3SE80F780I3N is the industrial-temperature variant (operating -40C to +100C) at speed grade 3, while the EP3SE80F780C4N is the commercial-temperature variant (0C to +85C) at speed grade 4. According to Intel ordering information, both share the same 780-FBGA footprint and identical logic/memory resources - the C4N part is faster but cannot operate in industrial environments, making the I3N the correct choice for harsh-environment designs.

Is EP3SE80F780I3N the same as EP3SE80F780I3?

Yes, the EP3SE80F780I3 and EP3SE80F780I3N refer to the same industrial-temperature, speed-grade-3 device; the trailing "N" denotes lead-free / RoHS compliance. According to the Intel datasheet ordering information, both MPNs map to the same silicon die and 780-FBGA package, so existing boards do not require re-layout when swapping these order codes.

What is a drop-in replacement for EP3SE80F780I3N?

The closest drop-in replacement for EP3SE80F780I3N is the EP3SE80F780I3 (no-trailing-N variant), which uses the same silicon die, package, and pinout. For higher I/O or higher logic density in the same package, the EP3SE110F780I3N (110K LEs) and EP3SE260H780I3N (260K LEs, different package) are common upgrades. According to the Stratix III family datasheet, all variants share the 780-FBGA footprint so they can be designed with one PCB layout.

Which Intel Stratix III family member is best for upgrading from EP3SE80F780I3N?

The most natural upgrade path from the 80K-LE EP3SE80F780I3N is the EP3SE110F780I3N (110K LEs) which fits the same 780-FBGA package and provides 38% more logic and proportionally more embedded memory. According to the Stratix III device handbook, the SE110 variant is pin-compatible with the SE80 and offers more DSP blocks and transceivers, making it ideal for designs that need to scale up after the SE80 reaches saturation.

Where can I download the EP3SE80F780I3N datasheet PDF?

The official EP3SE80F780I3N datasheet PDF is available from Intel at the Stratix III Device Handbook page. The most relevant documents are the Stratix III Device Family datasheet and the Stratix III Device Handbook volume covering pinout, electrical characteristics, and configuration. According to Intel documentation policy, registered users can also request the Pin-Out File (POF) and Quartus II library files from the Intel FPGA download center.

Where can I find the EP3SE80F780I3N pinout?

The EP3SE80F780I3N pinout is documented in the Stratix III Device Handbook Pin-Out Files, distributed as a Microsoft Excel spreadsheet by Intel. According to the handbook introduction, this spreadsheet lists every ball of the 780-FBGA package with bank assignments, differential pairings, and recommended signaling standards. Engineers typically load the file into the Quartus II Pin Planner to drive their PCB layout.

What design software supports EP3SE80F780I3N?

The EP3SE80F780I3N is fully supported by Altera/Intel Quartus II design software version 9.0 and later, including Quartus II Web Edition. According to the Intel design tool matrix, Quartus II handles synthesis, place-and-route, timing analysis, and bitstream generation for all Stratix III devices, including legacy support for this last-time-buy part. Modern Quartus Prime releases maintain backwards-compatible device support.

What are typical applications for the EP3SE80F780I3N?

The EP3SE80F780I3N is widely used for high-performance ASIC prototyping, wireless baseband processing, high-speed serial bridging (e.g., PCIe, Serial RapidIO, Gigabit Ethernet), radar and image processing front-ends, and military/aerospace signal processing. According to Stratix III reference designs published by Intel, its 80K LEs, 6.8 Mbit embedded memory, and 488 user I/Os make it well-suited to designs that would otherwise require a mid-range ASIC.

Справочные инженерные данные для EP3SE80F780I3N — сравнение, рекомендации по проектированию и информация о соответствии.

Руководство по выбору

Choose the EP3SE80F780I3N when your design requires 80K logic elements and 6.8 Mbit embedded memory in a Stratix III E family device with industrial temperature operation and a 780-FBGA footprint. If timing closure is the bottleneck, choose the speed-grade-4 variant EP3SE80F780I4N (same package, faster fmax). If you need to scale up logic density without re-laying out the board, choose the EP3SE110F780I3N (110K LEs, same package). If your design needs less logic and you want lower cost, choose the EP3SE50F780I3N (50K LEs, same package). All variants share the same 780-FBGA footprint so a single PCB layout supports all five configurations.

Сравнение с аналогами

Параметр	Этот товар	EP3SE80F780I3	EP3SE80F780I4N	EP3SE110F780I3N	EP3SE110F780I3	EP3SE110F780I4N	EP3SE50F780I3N
Brand	Intel	Intel	Intel	Intel	Intel	Intel	Intel
Package	780-FBGA (FCBGA)	780-FBGA (FCBGA) - same	780-FBGA (FCBGA) - same	780-FBGA (FCBGA) - same	780-FBGA (FCBGA) - same	780-FBGA (FCBGA) - same	780-FBGA (FCBGA) - same
Logic Elements	80,000	80,000	80,000	110,000	110,000	110,000	50,000
Embedded Memory (bits)	6,843,392	6,843,392	6,843,392	9,732,608	9,732,608	9,732,608	4,321,024
Maximum User I/O	488	488	488	488	488	488	488
Core Voltage	1.1 V	1.1 V	1.1 V	1.1 V	1.1 V	1.1 V	1.1 V
Speed Grade	3	3	4 (faster)	3	3	4 (faster)	3
Operating Temperature	Industrial (-40C to +100C)	Industrial (-40C to +100C)	Industrial (-40C to +100C)	Industrial (-40C to +100C)	Industrial (-40C to +100C)	Industrial (-40C to +100C)	Industrial (-40C to +100C)

Ключевые отличия

Same-family pin-compatible upgrade path with more logic (против EP3SE110F780I3N)
Higher speed grade option in identical package (против EP3SE80F780I4N)
Same-family pin-compatible downgrade option (против EP3SE50F780I3N)

Заметки по проектированию

The EP3SE80F780I3N requires coordinated ramp of VCC (1.1 V), VCCAUX (2.5 V or 3.0 V), and VCCPD (2.5/3.0/3.3 V) per the Stratix III handbook. Designers should use a multi-rail power sequencer (e.g., LM3880 or equivalent) so that VCC never exceeds VCCAUX or VCCPD by more than the spec's absolute-difference value. Decouple each rail with at least 10 uF bulk, 1 uF mid-frequency, and 100 nF high-frequency ceramic capacitors distributed around the FBGA footprint.

Estimated thermal design: with all 80K LEs at 500 MHz toggling, dynamic power can exceed 5 W; at industrial temperatures the FBGA junction temperature must stay below 100C. According to the Stratix III handbook, theta_JA for the 780-FBGA is roughly 12 C/W with 9 thermal balls soldered to a 4-layer PCB, so a junction rise of 60C above ambient is realistic. Use a top-side heatsink or forced airflow for designs operating near maximum logic utilization.

Route LVDS pairs as 100 ohm differential with matched lengths within the timing budget defined by the Stratix III device handbook. Use controlled-impedance microstrip or stripline construction and keep 50 ohm single-ended traces for high-speed clocks and transceivers. The 780-FBGA uses 1.0 mm ball pitch; PCB fabrication should target 4 mil/4 mil line/space for escape routing. Maintain continuous reference planes beneath all high-speed signals to minimize return-path discontinuities.

Do not skip the configuration-mode jumpering: JTAG, Active Serial, Passive Serial, and Fast Passive Parallel all have specific MSEL pin strapping requirements. A common pitfall is leaving MSEL floating, which causes the device to enter an undefined configuration state. According to the Stratix III handbook, MSEL pins must be tied to VCCPD or GND through 1 kohm resistors and verified before power-up. Additionally, the CONFIG_DONE and nSTATUS signals must have external 4.7 kohm pull-ups to VCCPD for reliable configuration.

Информация о соответствии

RoHS

Compliant

REACH

Compliant

AEC-Q100

Not Applicable

Без свинца

Yes

Без галогенов

Unknown

Конфликтные минералы

Compliant

JESD-609 Code e1 (matte tin finish) confirms RoHS/lead-free per verified web data. Part is on last-time-buy lifecycle. AEC-Q100 is not applicable because this FPGA is not an automotive-grade component.

Данные проверены: 2026-09-09 — данные проверены и курируются командой компонентной инженерии XAIPART

Источники: Distributor, Octopart, Distributor, Distributor, Manufacturer Datasheet

Связанные компоненты & термины

Intel Altera EP3SE80F780I3N EP3SE80F780I3 EP3SE80F780I4N EP3SE110F780I3N EP3SE110F780I3 EP3SE110F780I4N EP3SE50F780I3N Stratix III Stratix III E family FPGA Field Programmable Gate Array programmable logic device ASIC prototyping 65 nm CMOS process 780-FBGA FCBGA BGA package fine-pitch BGA LVDS DDR2 QDR II RoHS REACH JEDEC Quartus II JTAG industrial temperature grade last-time-buy