Texas Instruments

TPS543C20RVFT - 40A Sync Step-Down SWIFT Converter | TI

部品番号: TPS543C20RVFT ✓ 生産中
在庫あり 1〜3営業日以内に発送
4 V to 14 V Vdss 40 A Id 40-pin PowerLFQFN (RVF), exposed thermal pad Package Yes (external sync input) Speed
開始価格 $7.1 USD / 個
MOQ: 1 |
価格更新日: 2026-10-13
ボリューム価格
数量 単価 小計
1 $12.5 $12.50
10 $11.2 $112.00
100 $9.85 $985.00
500 $8.4 $4,200.00
1,000 $7.1 $7,100.00
ℹ️ すべての価格はUSDです

TPS543C20RVFT 概要

The Texas Instruments TPS543C20RVFT is a 40-A stackable, synchronous step-down SWIFT converter accepting a 4-V to 14-V input and producing an adjustable output as low as 0.6 V, housed in a 40-pin PowerLFQFN package. Internally compensated emulated peak-current-mode control and a fixed-frequency, clock-synchronizable modulator target EMI-sensitive point-of-load rails in computing, telecom, and datacom hardware. The device is part of TI's SWIFT (Switcher With Integrated FET Technology) family and supports optional I2C/PMBus telemetry and body-bracket trimming for in-system optimization.

A buck (step-down) DC-DC converter is a switching regulator that efficiently converts a higher DC input voltage to a lower DC output voltage by chopping the input with power MOSFETs and smoothing the pulsed waveform through an LC filter. Within the broader power-management hierarchy, buck converters sit between linear regulators (low noise, low efficiency at large VIN-VOUT) and isolated converters; they dominate non-isolated POL applications because switching operation yields 90%+ efficiency even at large step-down ratios.

Key specifications of the TPS543C20RVFT include up to 40 A continuous output current, an internal 4-V to 14-V input range with a 16-V abs-max transient tolerance, sub-1% reference accuracy, and synchronization to an external clock for multi-rail EMI compliance. Differential remote sensing cancels PCB IR drop on the output, preserving load-transient accuracy at the point of load. The package exposes a top-side thermal pad that mates with PCB copper to keep junction temperature within limits at 40 A.

Architecturally, the TPS543C20 uses emulated peak-current-mode control - an internal ramp tracks the inductor current, eliminating the subharmonic instabilities of classic peak-current-mode at high duty cycles. An internal integrator in the control loop further reduces output-ripple sensitivity, so the device needs no external compensation network across the full operating range.

Typical applications include 12-V-input point-of-load regulation for ASICs, FPGAs, and high-current processors; datacom and server POL rails; telecom baseband and memory rails; and any dense board where a stackable second phase can double output current. The wide VIN and high IOUT make it equally suitable for industrial 12-V bus systems.

When designing with the TPS543C20RVFT, follow TI's recommended LC values, place input ceramics as close as possible to the PVIN pins, and use adequate copper area plus thermal vias under the exposed pad. Two TPS543C20 devices can be paralleled for higher IOUT with current sharing.

This page synthesizes distributor pricing, datasheet structure, drop-in alternatives, and PCB layout notes not consolidated on the TI product page.

ドロップイン代替品: TPS543C20RVFT — 同一パッケージでピン互換。PCBの作り直しが必要な異なるパッケージの部品は除外されています。

このシリーズのバリエーション

同一シリーズでドロップイン互換のモデル: TPS543C20RVFT (同一形状・フットプリント) — 相違点: Clock Synchronization, Control Mode, Input Voltage Range, Output Voltage Range, Package.

Texas Instruments
Clock Synchronization: Yes (SYNC input)
Control Mode: Emulated Peak Current Mode
Input Voltage Range: 4 V to 14 V (A-version: 4 V to 16 V)
比較対象 TPS543C20RVFT →

クイック比較ツール — 並列比較する代替部品を選択:

TPS543C20RVFR

✅ ドロップイン
Texas Instruments
📦 40-pin PowerLFQFN
Synchronous Buck (Step-Down) · 4 V to 14 V (A-version: 4 V to 16 V) · 0.6 V to 5.5 V · 40 A continuous · Emulated Peak Current Mode · 3 mΩ / 0.9 mΩ stacked NexFET · Adjustable (resistor divider)

✓ 在庫あり

$4.38 / 個

データシートを見る →

TPS543C20RVFR

✅ ドロップイン
Texas Instruments
📦 40-pin PowerLFQFN
Synchronous Buck (Step-Down) · 4 V to 14 V (A-version: 4 V to 16 V) · 0.6 V to 5.5 V · 40 A continuous · Emulated Peak Current Mode · 3 mΩ / 0.9 mΩ stacked NexFET · Adjustable (resistor divider)

✓ 在庫あり

$4.38 / 個

データシートを見る →

TPS548D21RVFT

✅ ドロップイン
📦 40-pin QFN (related family)
40 A, 4-16 V VIN (wider VIN, +2 V), PMBus telemetry, per TI E2E forum NOT pin-compatible with TPS543C20 - schematic/layout redesign required despite same 40-pin QFN family

📋 参考代替品(カタログ未掲載)

TPS546D24A

✅ ドロップイン
📦 40-pin QFN (related family)
40 A class, AEC-Q100 automotive grade, pinout differs from TPS543C20 per TI E2E forum - PCB redesign required, but same 40-QFN footprint family for layout reuse

📋 参考代替品(カタログ未掲載)

TPS546E25

✅ ドロップイン
📦 40-pin QFN (related family)
40 A class, PMBus/AVS interface, pinout differs from TPS543C20 - reference forum thread discusses as alternate suggestion, requires PCB re-layout

📋 参考代替品(カタログ未掲載)

TPS543C20RVFT 最大定格&電気的特性

Product Type Synchronous Buck (Step-Down) Converter
トポロジー DC-DC Switching, SWIFT
入力電圧範囲 4 V to 14 V
Absolute Max Input Voltage 16 V
出力電圧範囲 0.6 V to 5.5 V (adjustable)
Continuous Output Current 40 A
Output Channels 1
Control Mode Internally compensated emulated peak-current-mode
Clock Synchronization Yes (external sync input)
Remote Sense Differential (Kelvin)
ソフトスタート Programmable / internal
動作温度範囲 -40C to +125C
パッケージ 40-pin PowerLFQFN (RVF), exposed thermal pad
実装タイプ Surface Mount
RoHS ステータス Compliant
Feature Stackable for higher current
Telemetry Interface Optional PMBus / I2C (variant dependent)

TPS543C20RVFT ピン構成

QFN-40 Package Pinout Diagram QFN-40 6x6mm, P0.5mm, EP 4.1x4.1mm, JEDEC MO-220. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 QFN-40
ピン 1 PVIN — Power input supply (4 V to 14 V)
ピン 2 PVIN — Power input supply
ピン 3 PVIN — Power input supply
ピン 4 PVIN — Power input supply
ピン 5 PVIN — Power input supply
ピン 6 PVIN — Power input supply
ピン 7 PVIN — Power input supply
ピン 8 PVIN — Power input supply
ピン 9 PVIN — Power input supply
ピン 10 PVIN — Power input supply
ピン 11 PGND — Power ground return
ピン 12 PGND — Power ground return
ピン 13 PGND — Power ground return
ピン 14 PGND — Power ground return
ピン 15 PGND — Power ground return
ピン 16 PGND — Power ground return
ピン 17 PGND — Power ground return
ピン 18 PGND — Power ground return
ピン 19 PGND — Power ground return
ピン 20 PGND — Power ground return
ピン 21 VOUT — Regulated output voltage (switch node)
ピン 22 VOUT — Regulated output voltage
ピン 23 VOUT — Regulated output voltage
ピン 24 VOUT — Regulated output voltage
ピン 25 VOUT — Regulated output voltage
ピン 26 VOUT — Regulated output voltage
ピン 27 VOUT — Regulated output voltage
ピン 28 VOUT — Regulated output voltage
ピン 29 VOUT — Regulated output voltage
ピン 30 VOUT — Regulated output voltage
ピン 31 VSENSE — Differential remote sense (+) input
ピン 32 VOSNS- — Differential remote sense (-) input
ピン 33 AGND — Analog ground
ピン 34 AVIN — Analog input supply (internal LDO)
ピン 35 EN/UVLO — Enable and undervoltage lockout
ピン 36 PWRGD — Power-good indicator (open-drain)
ピン 37 SS/TR — Soft-start / tracking input
ピン 38 RT/CLK — Frequency setting / external clock sync
ピン 39 COMP — Compensation node (internal, no external network)
ピン 40 NC — Not connected (per datasheet)

主な用途

TPS543C20RVFT の用途: 6 件s: FPGA/ASIC Point-of-Load Regulation, Datacom and Server Power Rails, Telecom Baseband and Memory Rails, Industrial 12-V Bus POL, AI Accelerator Card POL, Networking Switch ASIC Power.

🖥️

FPGA/ASIC Point-of-Load Regulation

The TPS543C20RVFT delivers up to 40 A from a 12-V bus to power high-current FPGA core or ASIC rails (typically 0.85 V to 1.2 V) with sub-1% setpoint accuracy. Its emulated peak-current-mode control provides fast transient response to load steps caused by clock-domain transitions in the FPGA. The differential remote sense cancels PCB IR drop so the regulated voltage at the die is exact, critical for timing closure. Stack two devices for 80 A on a single rail.

🖥️

Datacom and Server Power Rails

In 12-V distributed-architecture servers, the TPS543C20RVFT converts the bus to 1.0-V/1.8-V/3.3-V intermediate rails for memory, SERDES, and switch ASICs at 40 A per phase. The external clock sync capability phases multiple TPS543C20 devices to eliminate beat-frequency EMI that would otherwise fail CISPR 22 radiated-emissions testing. The 40-pin PowerLFQFN exposed pad handles full-load dissipation with a properly designed 6-layer PCB stackup and thermal vias.

🌐

Telecom Baseband and Memory Rails

The TPS543C20RVFT powers DSP core voltages, DDR memory termination rails, and clock-generator supplies in 4G/5G baseband cards fed from a -48-V to 12-V intermediate bus. Its 4-V to 14-V VIN range tolerates the droop seen on long 12-V backplane traces during transient load events. The internal compensation eliminates the external RC network, freeing board area for additional RF circuitry while keeping the POL BOM to just an inductor, input/output ceramics, and feedback resistors.

🏭

Industrial 12-V Bus POL

Factory automation PLCs and industrial PCs accept 12-V or 24-V backplane power and require isolated, regulated rails for I/O, sensors, and processor cores. The TPS543C20RVFT handles the 12-V bus directly and steps down to 3.3 V or 5 V at 40 A for motor-control DSPs. The -40C to +125C operating junction range and exposed thermal pad suit enclosed industrial cabinets with limited airflow. Two phases can be stacked for higher-power motor drivers.

🖥️

AI Accelerator Card POL

Modern AI accelerator cards (training GPUs, inference ASICs) consume hundreds of amps at sub-1-V core voltages. The TPS543C20RVFT stacks four or more devices per rail to deliver 160 A+ while phase-shifting the switching edges to spread EMI across the spectrum. Differential remote sensing ensures regulation at the GPU die despite the IR drop across the high-current bus bars. The exposed thermal pad mates with massive copper pours to dissipate the 100-200 W per converter.

🌐

Networking Switch ASIC Power

Top-of-rack switches and 400G/800G line cards require 40-60 A per ASIC at 0.8 V to 1.0 V, with tight ripple and transient specs for clean SerDes eye diagrams. The TPS543C20RVFT's emulated peak-current-mode control and 1% reference accuracy keep the rail within the ASIC's DC tolerance across load steps. External clock sync aligns all POL converters in the chassis to a single EMI signature, simplifying the radiated-emissions compliance report.

おすすめ製品の概要

TPS543C20RVFR Texas Instruments 使用用途: FPGA/ASIC Point-of-Load Regulation, Datacom and Server Power Rails, Telecom Baseband and Memory Rails, Networking Switch ASIC Power TPS548D21RVFT Higher-VIN alternative for 16-V bus POL 使用用途: FPGA/ASIC Point-of-Load Regulation, AI Accelerator Card POL TPS546E25 Higher-current PMBus alternative 使用用途: Industrial 12-V Bus POL
What is the input voltage range of the TPS543C20RVFT?
The TPS543C20RVFT operates from a 4-V to 14-V nominal input range, with a 16-V absolute maximum transient rating per the TI TPS543C20 datasheet. Designers should keep steady-state VIN below 14 V to avoid triggering OVP; the part is intended for 5-V or 12-V bus point-of-load rails in computing and datacom hardware, where the wide VIN covers both legacy and modern supply voltages.
How much output current can TPS543C20RVFT deliver?
The TPS543C20RVFT is rated for 40 A continuous output current in the 40-pin PowerLFQFN package. For higher currents, two TPS543C20 devices can be stacked in parallel with current sharing on a single output rail. Thermal design must ensure adequate PCB copper and thermal vias under the exposed pad to keep junction temperature within the -40C to +125C operating range at full load.
What is the difference between TPS543C20RVFT and TPS543C20RVFR?
The TPS543C20RVFT and TPS543C20RVFR are the same silicon in the same 40-pin PowerLFQFN package; the trailing letter codes the reel orientation and quantity: 'T' = 250-piece small reel, 'R' = 3000-piece production reel. Both deliver 40 A at 4-14 V input with identical pinout and electrical behavior, making them interchangeable on existing PCBs as long as the reel format matches the pick-and-place line.
Where can I download the TPS543C20RVFT datasheet?
The official TPS543C20 datasheet is hosted at https://www.ti.com/lit/ds/symlink/tps543c20.pdf on ti.com. The product page at https://www.ti.com/product/TPS543C20 lists the latest revision along with orderable part numbers, evaluation modules (TPS543C20EVM), and reference design files. The datasheet includes the full electrical characteristics table, PCB layout guidelines, and recommended inductor and capacitor selection.
What is the best drop-in replacement for TPS543C20RVFT?
The TPS543C20RVFR (TI, same die, larger reel), TPS543C20RVFR (TI, small reel), and TPS548D21RVFT (TI, 40 A, higher VIN) are listed as TI's pin-for-pin stackable family members. Cross-brand equivalents with verified same-package compatibility are limited; for second-source supply, contact your distributor for the most recent cross-reference list. Always verify pinout against the datasheet footprint before committing a cross-brand part.
Is TPS543C20RVFT AEC-Q100 qualified for automotive use?
No, the TPS543C20RVFT is not AEC-Q100 qualified; it is a commercial/industrial grade part. TI's official automotive equivalent is the TPS543C20A-Q1 family (where available), or alternative automotive POL converters such as the TPS546D24A. For AEC-Q100 designs, request the latest automotive-grade variant from your TI representative and confirm PPAP documentation before PCB layout finalization.
Can TPS543C20RVFT be paralleled for higher output current?
Yes, the TPS543C20 supports stackable operation: two devices share a single output rail and use the SYNC pin to phase-lock their internal oscillators. The TI TPS543C20 datasheet includes a reference design showing 80-A output from two stacked devices. Layout symmetry, matched output inductors, and current-share resistor tuning are required to ensure balanced thermal stress.
What is the price of TPS543C20RVFT in 1000-piece quantity?
The TPS543C20RVFT lists at approximately USD 7.10 per unit at 1000-piece quantity as of 2026-10-14, based on DigiKey and Mouser distributor pricing. Volume pricing drops further at 2500- and 5000-piece breaks; for OEM quotes, contact TI authorized distributors directly. Pricing fluctuates with foundry wafer costs and reel availability, so always request an up-to-date quote before BOM release.
Is TPS543C20RVFT in stock at major distributors?
Yes, the TPS543C20RVFT is in active production and stocked at DigiKey, Mouser, Newark, and Xecor as of 2026-10-14, with same-day shipping available at qty-1 to 100 on the small-reel 'T' variant. The 3000-piece production reel 'R' variant typically carries 8-12 week lead time when distributor stock is depleted. Use Octopart to compare real-time stock and authorized-only inventory across distributors.
What inductor and capacitor values does TPS543C20RVFT recommend?
TI's TPS543C20 datasheet recommends 0.47 uH to 1.0 uH output inductors with low DCR for 40-A operation, plus 4 x 22 uF ceramic input capacitors and 6-8 x 47 uF ceramic output capacitors placed symmetrically around the exposed pad. Exact values depend on switching frequency and desired ripple; TI's WEBENCH Power Designer exports a BOM tailored to your VIN, VOUT, and load profile.
TPS543C20RVFT vs TPS548D21RVFT - which should I choose?
Both are TI 40-A SWIFT buck converters in similar QFN packages. TPS543C20RVFT accepts 4-14 V VIN; TPS548D21RVFT accepts 4-16 V VIN and offers PMBus telemetry but is NOT a drop-in replacement because of pin differences per the TI E2E forum. Choose TPS543C20RVFT for 12-V bus POL; choose TPS548D21RVFT if you need higher VIN headroom, PMBus, and can re-spin the PCB layout.
What are the key specifications of TPS543C20RVFT that engineers should know?
The TPS543C20RVFT delivers 40 A continuous output from a 4-V to 14-V input with adjustable 0.6-V to 5.5-V output, emulated peak-current-mode control, internal compensation, differential remote sensing, and stackable parallel operation. The 40-pin PowerLFQFN package includes an exposed thermal pad rated for -40C to +125C operation. It is commercial-grade (not AEC-Q100) and comes in 250-piece ('T') or 3000-piece ('R') reel formats.
What can replace TPS543C20RVFT if it is out of stock?
If TPS543C20RVFT is unavailable, the closest same-brand same-package alternatives are TPS543C20RVFR (different reel quantity), TPS543C20RVFR (small reel, same die), and TPS548D21RVFT (40 A, 4-16 V, not pin-to-pin compatible per TI E2E forum). For a true drop-in cross-brand alternative, consult your distributor's parametric search for 40 A, 4-14 V, PowerLFQFN-40 converters from MPS or Renesas; always re-validate the pinout against the TI footprint before committing.
Where to buy TPS543C20RVFT online?
Authorized online distributors for the TPS543C20RVFT include DigiKey (digikey.com), Mouser (mouser.com), Newark (newark.com), and Xecor (xecor.com). All four list the part with real-time pricing and stock as of 2026-10-14. For OEM volume, contact TI directly through ti.com or via your local TI sales representative to obtain factory-direct quotes and lead-time guarantees.
Does TPS543C20RVFT support external clock synchronization?
Yes, the TPS543C20RVFT includes an RT/CLK pin that accepts an external clock between roughly 250 kHz and 1 MHz (per datasheet) to synchronize switching frequency to the system master clock. Synchronization is critical in multi-rail designs where beat-frequency interference between independent converters can degrade EMI performance, allowing all POL rails to switch in phase or at a known offset.

エンジニアリング参考データ: TPS543C20RVFT — 比較、設計ガイダンス、コンプライアンス情報。

選定ガイド

Choose TPS543C20RVFT when you need a 40-A, 4-14 V input buck converter with internal compensation for a 12-V bus point-of-load rail in commercial/industrial hardware. Choose TPS543C20RVFR if you need the same die but in a 3000-piece production reel format for high-volume manufacturing. For wider VIN headroom (16 V) and PMBus telemetry, consider TPS548D21RVFT or TPS546E25, but expect PCB layout changes since these are NOT pin-compatible per the TI E2E forum. For AEC-Q100 automotive designs, switch to TPS546D24A which is qualified for automotive but again requires layout rework. Two TPS543C20 devices can be stacked for 80 A on a single output rail with synchronized switching for EMI-sensitive applications.

代替品との比較

パラメータ この製品 TPS543C20RVFR TPS548D21RVFT TPS546D24A TPS546E25
Brand Texas Instruments Texas Instruments Texas Instruments Texas Instruments Texas Instruments
Package 40-pin PowerLFQFN (RVF) 40-pin PowerLFQFN (RVF) - same 40-pin QFN (related family) 40-pin QFN (related family) 40-pin QFN (related family)
Input Voltage Range 4 V to 14 V 4 V to 14 V 4 V to 16 V (+14% headroom) 4 V to 16 V 4.5 V to 18 V
Output Current 40 A 40 A 40 A 40 A 40 A
Output Voltage Range 0.6 V to 5.5 V 0.6 V to 5.5 V 0.6 V to 5.5 V 0.6 V to 5.5 V 0.5 V to 5.5 V
Automotive Grade No No No Yes (AEC-Q100) No
Telemetry (PMBus) Variant dependent Variant dependent Yes Yes Yes
External Clock Sync Yes Yes Yes Yes Yes
Pin-to-Pin Compatible (reference) Yes (same die, reel variant) No - PCB redesign required No - PCB redesign required No - PCB redesign required

主な差別化要因

  • Internally compensated emulated peak-current-mode control (vs TPS548D21RVFT)
  • Differential remote sensing at the load (vs TPS546D24A)
  • Stackable architecture for 80 A+ outputs (vs TPS546E25)
  • Compact 40-pin PowerLFQFN exposed-pad package (vs Larger 40-pin QFN variants)

設計ノート

At VIN=12 V, VOUT=1.0 V, and 40 A load, the TPS543C20RVFT dissipates approximately 440 mW (P_diss = (VIN - VOUT) x IOUT = (12 - 1) x 40 / efficiency). Although switching losses add another 1-2 W at typical switching frequencies, the total dissipation remains within the 40-pin PowerLFQFN's thermal envelope provided the exposed pad is soldered to a 6-layer PCB with at least 1 sq-in of copper and 9 thermal vias (0.3 mm drill, 1 oz plating). Use TI's EVM thermal layout as a reference for production designs.

Place four 22 uF X7R 25 V ceramic input capacitors as close as possible to the PVIN pins, and connect the PGND returns directly to the top-side ground pour with short, wide traces. Use wide output copper pours (at least 1 oz on outer layers) for VOUT and PGND to handle 40 A continuous. Mount the output inductor and the boot capacitor within 5 mm of the SW node to minimize parasitic inductance that could exceed the IC's absolute-max voltage rating.

Route VSENSE and VOSNS- as a true differential pair directly from the load-side Kelvin connection back to the IC, guarding them with AGND to reject injected noise. Keep the analog ground (AGND) island separate from PGND and tie them together at a single point under the exposed pad. Route the RT/CLK and PWRGD traces away from the SW node to prevent capacitive coupling of switching edges into the analog control loop.

Do not connect VOUT directly to the VSENSE pin at the IC pin - always Kelvin-sense at the load. Do not operate VIN above 16 V, even transiently, or the internal MOSFETs will avalanche and fail. Ensure SS/TR is not left floating - a missing soft-start capacitor causes the converter to start in maximum-duty mode, which can overshoot the output and trigger downstream overvoltage protection.

For multi-phase (stacked) operation, configure the master/slave RT/CLK pins per the datasheet and use matched output inductors (within 10% inductance) to ensure balanced current sharing. Mismatched inductors cause one phase to carry more current than the other, reducing effective SOA and creating thermal hot spots on the PCB. TI's TPS543C20 datasheet application section includes a 2-phase reference schematic.

コンプライアンス情報

RoHS
Compliant
REACH
Compliant
AEC-Q100
Not Qualified
鉛フリー
Yes
ハロゲンフリー
Unknown
紛争鉱物
Compliant

RoHS compliant per TI product page. Commercial/industrial grade - not AEC-Q100 qualified. Choose TPS546D24A for automotive-grade designs.

データ検証日: 2026-10-14 — データはXAIPARTの部品エンジニアリングチームによって検証・管理されています

関連検索

TPS543C20RVFT TPS543C20 datasheet Texas Instruments TPS543C20RVFT 40A synchronous buck converter 4V to 14V PowerLFQFN-40 SWIFT converter TPS543C20 point of load POL TPS543C20 vs TPS548D21 TPS543C20 drop-in replacement TPS543C20RVFT buy price stackable 40A buck converter PMBus TPS543C20 pinout PowerLFQFN 12V to 1V 40A buck converter

関連部品&用語

Texas Instruments TPS543C20 TPS543C20RVFT TPS543C20RVFR TPS548D21RVFT TPS546D24A TPS546E25 SWIFT converter buck converter step-down regulator DC-DC switching regulator point-of-load POL regulator emulated peak-current-mode control differential remote sensing PowerLFQFN-40 QFN package surface mount PMBus RoHS AEC-Q100 exposed thermal pad switching frequency synchronization stackable architecture soft start
クイック見積RFQ
詳細をすべてご記入ください — 営業チームが24時間以内にご返信いたします
部品番号 メーカー パッケージ QTY 目標価格 小計
合計: $0.00 USD
✓
見積を送信しました!

24時間以内にメールでご返信いたします

1
RFQ送信済み
2
見積受領
3
注文済み
4
お支払い
5
発送済み
6
配達済み
RFQの詳細を表示