My Inquiry
My Account
Analog Devices Inc./Maxim Integrated DS21S07AE+
- Part No.:
- DS21S07AE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Signal Terminators
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
DS21S07AE+.pdf
- Description:
- IC TERMINATOR SCSI 20-TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,489
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
DS21S07AE+ from Maxim Integrated is a 20-pin TSSOP SCSI active terminator IC designed for single-ended Fast and Ultra SCSI bus termination. It integrates nine laser-trimmed 110Ω resistors (±2% tolerance), a low-dropout 2.85V regulator, and power-down isolation logic. It operates from 4.0V–5.5V TERMPWR and delivers 24mA per line in active state, enabling robust termination in RAID controllers and hot-pluggable disk drives.
For engineers reviewing the DS21S07AE+ datasheet, DS21S07AE+ pinout, DS21S07AE+ application, or DS21S07AE+ equivalent, key selection criteria include termination resistance accuracy, TERMPWR voltage range, thermal shutdown threshold, power-down leakage, and compatibility with actively negated SCSI signaling.
Technical Context
The DS21S07AE+ implements a bandgap-referenced buffer amplifier driving nine switched 110Ω termination resistors, with precise 2.85V output (2.79V–2.93V) and ≤0.75V dropout. It supports bidirectional current handling: sourcing ≥24mA per line when signal is low, sinking ≥200mA for actively negated signals while maintaining VREF shift <60mV.
Power-down mode is activated by pulling PD low (≤0.8V), disabling all termination transistors and reducing quiescent current to ≤150µA; PD features an internal 50kΩ pullup, requiring only open-circuit connection for normal operation. Thermal shutdown triggers at 150°C and is guaranteed by design.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Termination Resistance | 108–112Ω (laser-trimmed ±2% tolerance ensures stable impedance matching on SCSI lines) |
| Reference Voltage | 2.79–2.93V (tight 2.85V typical output enables accurate high-level noise margin) |
| TERMPWR Range | 4.0–5.5V (supports standard SCSI bus power rails without external regulation) |
| Drop-Out Voltage | ≤0.75V (maintains regulation even under low-TERMPWR conditions during system brownout) |
| Power-Down Current | ≤150µA (enables bus isolation during hot-plug without affecting adjacent devices) |
| Thermal Shutdown | 150°C (on-die protection prevents latch-up or damage during sustained overload) |
| Sink Current Capability | ≥200mA (handles actively negated SCSI signals without reference collapse) |
Pinout & Package
DS21S07AE+ is housed in a 20-pin Thin Shrink Small Outline Package (TSSOP) with exposed thermal pad (HS-GND). The package measures 6.5mm × 4.4mm × 1.2mm and is lead-free (RoHS-compliant), marked "DS21T07E" on top.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 11 | TERMPWR1 / TERMPWR2 | Dual termination power inputs-must both connect to SCSI TERMPWR line and decouple with ≥2.2µF capacitor each |
| 3–7, 13–16 | R1–R9 | Nine 110Ω switched termination resistors-each connects to one SCSI signal line (e.g., BSY, SEL, ACK) |
| 9, 19 | VREF1 / VREF2 | Reference voltage outputs-must be shorted externally and decoupled with 4.7µF tantalum capacitor to ground |
| 10 | GND | Signal ground reference for regulator and termination circuitry |
| 2, 8, 12, 18 | HS-GND | Thermal pad connection-must be grounded for thermal dissipation or electrically isolated if unused |
| 20 | PD | Active-low power-down control-internal 50kΩ pullup allows activation via open-circuit; strap low to isolate terminators |
| 17 | NC | No connection-must remain unconnected to avoid functional interference |
Key Features
| Feature | Design Value |
|---|---|
| Fully compliant active termination | Meets SCSI-1, Fast SCSI, and Ultra SCSI standards for single-ended buses with intrinsic TERMPWR decoupling |
| Laser-trimmed precision resistors | 110Ω ±2% tolerance ensures consistent signal integrity across all nine terminated lines |
| Hot-plug compatible isolation | Power-down mode removes DS21S07AE+ electrically from bus-no physical removal needed during live insertion |
| Actively negated signal support | Sinks ≥200mA while limiting VREF shift to <60mV-preserves reference stability during differential-like assertion |
| On-die thermal protection | 150°C shutdown threshold prevents thermal runaway in high-density storage enclosures |
Applications
| RAID Controller Termination | Disk Drive Backplane |
|---|---|
Use Scenario: Terminating both ends of an 8-bit ("A") or 16-bit ("P") SCSI cable in enterprise RAID arrays with multiple hot-swap bays. IC Role / Device Role / Timing Role: Active SCSI terminator providing regulated 2.85V bias and 110Ω line matching for BSY, SEL, ACK, and data lines. Use Value: Eliminates voltage drop sensitivity on TERMPWR and improves noise immunity over passive terminators in multi-device configurations. | Use Scenario: Embedded termination on SAS/SATA-to-SCSI bridge boards or legacy drive backplanes supporting mixed SCSI peripherals. IC Role / Device Role / Timing Role: Monolithic termination solution replacing discrete resistor networks and regulators on space-constrained backplane PCBs. Use Value: Reduces component count by nine 110Ω resistors + regulator + decoupling, saving >25mm² board area per DS21S07AE+. |
| SCSI Hot-Swap Module | Industrial SCSI Data Acquisition |
Use Scenario: Termination inside modular SCSI I/O modules that plug into powered-backplane chassis without bus interruption. IC Role / Device Role / Timing Role: Bus-isolatable terminator activated/deactivated via PD pin to prevent glitches during insertion/removal. Use Value: Enables true hot-plug compliance-DS21S07AE+ draws ≤150µA in power-down and re-enables within microseconds of PD release. | Use Scenario: Reliable termination in ruggedized test equipment and factory-floor data loggers using legacy SCSI peripherals. IC Role / Device Role / Timing Role: High-immunity active terminator sustaining operation across 0°C–70°C ambient with thermal shutdown backup. Use Value: Maintains signal integrity under voltage sags (4.0V TERMPWR minimum) and EMI-rich industrial environments due to low-noise bandgap reference. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar SCSI active termination applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS21S07AS+ | 16-pin SO package; identical electrical specs but larger footprint and no HS-GND thermal pad | Better suited for through-hole or legacy SO-based designs where thermal density is lower | Select DS21S07AS+ when board layout lacks space for TSSOP or requires SO-compatible reflow profile |
| MAX3221ESE+ | RS-232 transceiver-not a SCSI terminator; lacks integrated resistors, regulator, or PD control | Not functionally equivalent; used for serial interface level translation, not bus termination | Not a valid alternative-only consider if misidentified as SCSI component; verify part function before substitution |
Compared with DS21S07AS+, DS21S07AE+ offers superior thermal management via HS-GND and smaller footprint, while MAX3221ESE+ serves entirely different interface functions and must not be substituted for SCSI termination.
Availability
DS21S07AE+ is available at Aetrix Electronics and suitable for RAID controller design, SCSI backplane integration, and industrial hot-swap module development requiring stable component supply, RoHS compliance, and long-term lifecycle support.
Supply support for DS21S07AE+ 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
Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in analog, mixed-signal, and power management ICs for industrial, communications, and computing applications.
The DS21S07AE+ belongs to Maxim's legacy SCSI interface product line, engineered specifically to replace bulky passive termination networks with monolithic, thermally robust, and hot-plug–ready active termination solutions.
FAQ
What is the operating temperature range for DS21S07AE+?
The DS21S07AE+ is specified for operation from 0°C to +70°C ambient temperature. This range aligns with commercial-grade SCSI peripheral requirements and is validated across all electrical parameters including termination resistance, reference voltage, and power-down current. Storage temperature extends to –55°C to +125°C. DS21S07AE+ does not support extended or industrial temperature grades.
How should the VREF pins be connected on DS21S07AE+?
VREF1 (Pin 9) and VREF2 (Pin 19) must be shorted together externally on the PCB and decoupled to ground with a single 4.7µF tantalum capacitor. This configuration stabilizes the internal reference and ensures proper regulator output. Failure to connect VREF1 and VREF2 directly results in undefined behavior and potential termination failure. DS21S07AE+ requires no additional filtering beyond this capacitor.
Does DS21S07AE+ support actively negated SCSI signals?
Yes, DS21S07AE+ fully supports actively negated SCSI signals. Its buffer amplifier sinks ≥200mA while limiting VREF shift to less than 60mV, preserving reference integrity during assertion of signals like BSY or SEL. This capability is explicitly verified in the functional description and DC characteristics table, distinguishing DS21S07AE+ from basic passive or non-sinking active terminators.
What is the purpose of the HS-GND pins on DS21S07AE+?
The HS-GND pins (2, 8, 12, 18) connect internally to the exposed thermal pad of the TSSOP package. They must be either soldered to a solid ground plane for thermal dissipation or left electrically isolated if thermal performance is not required. Proper grounding of HS-GND reduces junction temperature rise during sustained current draw, extending reliability in dense RAID or backplane layouts where DS21S07AE+ operates continuously.
Can DS21S07AE+ be used in differential SCSI systems?
No, DS21S07AE+ is designed exclusively for single-ended SCSI buses (SCSI-1, Fast SCSI, Ultra SCSI). It does not support differential signaling (e.g., HVD or LVD SCSI), which requires separate differential receivers, drivers, and termination schemes. Using DS21S07AE+ on a differential bus will result in incorrect termination, signal reflection, and communication failure. Always confirm bus topology before selecting DS21S07AE+.
DS21S07AE+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Type:
- SCSI, LVD, SE
- Number of Terminations:
- 9
- Voltage - Supply:
- 4V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP
DS21S07AE+ FAQ
1.How can I place an order for DS21S07AE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for DS21S07AE+ 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 DS21S07AE+ reliable?
The price and inventory of DS21S07AE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS21S07AE+ is usually 5 days.
3.What payment methods are accepted for DS21S07AE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS21S07AE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS21S07AE+?
DS21S07AE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS21S07AE+ 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 DS21S07AE+?
For technical support, including DS21S07AE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS21S07AE+ requirements.
6.How does Aetrix verify that DS21S07AE+ is sourced from the original manufacturer or authorized distributors?
All DS21S07AE+ 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 DS21S07AE+ meets industry standards.
7.What is the process for return or replacement of DS21S07AE+?
All DS21S07AE+ units undergo pre-shipment inspection (PSI). If there is an issue with DS21S07AE+, 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 DS21S07AE+ part is unused and in its original packaging.
Return procedure for DS21S07AE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
DS21S07AE+ Tags
-
LTC1344IG#PBF
Analog Devices Inc.
-
LTC1344AIG#PBF
Analog Devices Inc.
-
UCC5672PWP
Texas Instruments
-
LTC1344ACG#PBF
Analog Devices Inc.
-
MXL1344ACAG+
Analog Devices Inc./Maxim Integrated
-
LTC1344CG#PBF
Analog Devices Inc.
-
PACUSB-U3R
onsemi
-
PACUSB-D1Y5R
onsemi
-
FAN1804MCX
Fairchild Semiconductor
-
MCCS142237DT
onsemi
-
MCCS142237DTR2
onsemi
-
UCC5519PWPR
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
