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Analog Devices Inc./Maxim Integrated DS21S07AE/T&R
- Part No.:
- DS21S07AE/T&R
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Signal Terminators
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
DS21S07AE/T&R.pdf
- Description:
- IC TERMINATOR SCSI 20-TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,595
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Product details
Overview
DS21S07AE/T&R from Maxim Integrated is a 20-pin TSSOP SCSI active terminator IC for single-ended Fast and Ultra SCSI bus systems. It integrates a low-dropout 2.85V regulator and nine laser-trimmed 110Ω ±2% termination resistors, delivering 24mA sink/source per line and supporting hot-plug operation with power-down isolation. Used in RAID controllers and disk drive backplanes.
For engineers reviewing the DS21S07AE/T&R datasheet, DS21S07AE/T&R pinout, DS21S07AE/T&R application, or DS21S07AE/T&R equivalent, key selection criteria include TERMPWR voltage range (4.0–5.5V), VREF output stability (2.79–2.93V), thermal shutdown threshold (150°C), and TSSOP-20 mechanical compatibility with high-density SCSI layouts.
Technical Context
The DS21S07AE/T&R implements an integrated bandgap reference and buffer amplifier to generate a precise 2.85V termination voltage, sourcing ≥24mA per signal line when pulled low and sinking ≥200mA for actively negated SCSI signals. Its internal 50kΩ pull-up on PD enables open-circuit activation without external biasing.
It requires external 4.7µF decoupling between VREF1/VREF2 and ground, dual TERMPWR connections (TERMPWR1/TERMPWR2), and supports full electrical isolation via power-down mode-critical for hot-swap compliance in server storage subsystems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Termination Resistance | 110Ω ±2% (laser-trimmed; ensures impedance match across all 9 lines) |
| VREF Output Voltage | 2.85V (typ), 2.79–2.93V (min/max); stable reference for SCSI signal level integrity |
| TERMPWR Input Range | 4.0V to 5.5V; compatible with standard SCSI bus power rails |
| Quiescent Current | 2.5–5mA (active mode); enables low-power termination in idle bus states |
| Power-Down Current | 100–150µA; isolates termination resistors from bus during hot-plug events |
| Thermal Shutdown | 150°C (trigger point); protects against overtemperature failure in enclosed enclosures |
| Drop-Out Voltage | 0.50–0.75V; allows regulation down to 4.0V TERMPWR input |
Pinout & Package
DS21S07AE/T&R is housed in a 20-pin Thin Shrink Small Outline Package (TSSOP) with 0.65mm pitch, 4.4mm × 6.5mm body size, and exposed thermal pad (HS-GND) for enhanced heat dissipation in high-density storage PCBs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (TERMPWR1) | Termination Power Input | Primary TERMPWR connection; must be decoupled with 2.2µF or 4.7µF capacitor |
| 2,8,12,18 (HS-GND) | Heat Sink Ground | Internally tied to thermal pad; improves thermal performance when soldered to ground plane |
| 3–7,13–16 (R1–R9) | Signal Termination Node | Direct connection to SCSI signal lines (DB0–DB8, ACK, REQ, etc.); 110Ω termination path |
| 9 (VREF1) | Reference Voltage Output | Must be externally shorted to VREF2; supplies regulated 2.85V to all termination resistors |
| 10 (GND) | Signal Ground Reference | 0V return for regulator and termination circuitry; separate from HS-GND but tied at system ground |
| 11 (TERMPWR2) | Secondary TERMPWR Input | Redundant TERMPWR connection; improves noise immunity and current sharing |
| 17 (NC) | No Connection | Unbonded pin; must remain unconnected to avoid parasitic coupling |
| 19 (VREF2) | Reference Voltage Output | Must be externally shorted to VREF1; completes reference loop for regulator stability |
| 20 (PD) | Active-Low Power-Down Control | Internal 50kΩ pull-up; open-circuit = active; grounded = isolation of all R1–R9 from bus |
Key Features
| Feature | Design Value |
|---|---|
| Fully compliant with SCSI-1, Fast SCSI, Ultra SCSI | Meets ANSI X3.131-1994 and X3.277-1996 standards for active termination timing and voltage levels |
| Laser-trimmed 110Ω resistors (±2% tolerance) | Ensures consistent signal integrity across all 9 terminated lines without external calibration |
| Low-dropout regulator (0.50–0.75V drop) | Enables reliable 2.85V VREF generation even at minimum 4.0V TERMPWR supply |
| SCSI bus hot-plug compatibility | Power-down mode and internal PD pull-up allow safe insertion/removal without bus disruption |
| On-board thermal shutdown (150°C) | Prevents latch-up or damage during sustained high-current termination or ambient overheating |
Applications
| RAID Controller Backplane | Disk Drive Internal Termination |
|---|---|
Use Scenario: Termination of 16-bit "P" cable SCSI bus at controller end with three DS21S07AE/T&R devices. IC Role / Device Role / Timing Role: Active termination IC providing regulated 2.85V bias and 110Ω line matching for DB0–DB15, ACK, REQ, MSG, SEL, BSY, C/D, I/O, ATN, and RST. Use Value: Eliminates need for discrete resistor networks and external regulators, reducing BOM count by >12 components per termination point. | Use Scenario: Embedded termination inside enterprise SATA-to-SCSI bridge modules where physical space limits discrete solutions. IC Role / Device Role / Timing Role: Hot-plug-capable terminator enabling dynamic SCSI bus reconfiguration during drive replacement. Use Value: Enables zero-downtime maintenance in mission-critical storage arrays via PD-controlled electrical isolation. |
| SCSI Tape Library Interface | Legacy Server Storage Expansion Card |
Use Scenario: Termination of differential SCSI-2 "A" cable segments connecting tape autoloaders to host adapters. IC Role / Device Role / Timing Role: Provides matched 110Ω termination for 8-bit data + control lines while rejecting common-mode noise via dual TERMPWR inputs. Use Value: Improves signal margin by 3.2dB over passive terminators under 10m cable length and 10MHz clock conditions. | Use Scenario: Retrofitting legacy PCI-based SCSI host adapters with modern active termination for Ultra SCSI-3 compliance. IC Role / Device Role / Timing Role: Replaces obsolete DS2107A with identical pinout and function in existing SO-16 footprints (via adapter or redesign to TSSOP-20). Use Value: Restores full Fast/Ultra SCSI timing margins without changing PCB layout or firmware. |
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/T&R | 16-pin SO package; same electrical specs; no HS-GND thermal pad | Lower thermal performance in high-density, convection-limited environments | Select DS21S07AS/T&R only when board layout constraints prohibit TSSOP-20 or thermal management is handled externally |
| MAX3243ESE+ | RS-232 transceiver with integrated charge-pump; not a SCSI terminator | Not functionally equivalent; serves serial interface, not bus termination | Not a valid alternative; DS21S07AE/T&R has no direct pin-compatible replacement outside Maxim's DS21x07 family |
Compared with DS21S07AS/T&R, DS21S07AE/T&R offers superior thermal dissipation via HS-GND pins and higher pin density, while MAX3243ESE+ serves unrelated communication protocols and cannot substitute for SCSI termination functionality.
Availability
DS21S07AE/T&R is available at Aetrix Electronics and suitable for RAID controller backplanes, enterprise disk drive modules, SCSI tape library interfaces, and legacy server storage expansion cards requiring stable component supply and long-term industrial availability.
Supply support for DS21S07AE/T&R 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) designs precision analog, mixed-signal, and power management ICs for industrial, communications, and computing applications.
The DS21S07AE/T&R belongs to Maxim's SCSI interface product line, engineered specifically for robust, standards-compliant active termination in mission-critical storage subsystems operating across 0°C to +70°C.
FAQ
What is the operating temperature range for DS21S07AE/T&R?
The DS21S07AE/T&R is specified for operation from 0°C to +70°C. This commercial-grade range aligns with typical server and storage enclosure ambient conditions. The device incorporates on-die thermal shutdown at 150°C to prevent damage during transient overtemperature events. DS21S07AE/T&R does not support extended or industrial temperature grades.
How many signal lines does DS21S07AE/T&R terminate?
The DS21S07AE/T&R terminates nine SCSI signal lines (R1–R9), covering core signals such as DB0–DB8, ACK, REQ, MSG, SEL, BSY, C/D, I/O, ATN, and RST depending on bus width configuration. Each line uses a dedicated 110Ω ±2% laser-trimmed resistor. DS21S07AE/T&R must be used in multiples (e.g., two or three units) to fully terminate 8-bit or 16-bit SCSI buses.
What is the purpose of the HS-GND pins on DS21S07AE/T&R?
The HS-GND pins (pins 2, 8, 12, 18) on DS21S07AE/T&R are internally connected to the exposed thermal pad of the TSSOP-20 package. They provide a low-thermal-resistance path to the PCB ground plane, improving heat dissipation during sustained 24mA per-line operation. Proper soldering of these pins to a thermal pad is required to maintain junction temperature within specification under full load.
Can DS21S07AE/T&R be used with differential SCSI buses?
No, DS21S07AE/T&R is designed exclusively for single-ended SCSI buses (SCSI-1, Fast SCSI, Ultra SCSI). It does not support differential signaling or LVDS-based SCSI variants like LVD or HVD. For differential SCSI termination, separate active terminators rated for 110Ω differential impedance and compatible voltage levels are required. DS21S07AE/T&R's architecture assumes single-ended logic levels referenced to TERMPWR and GND.
What capacitor values are required for DS21S07AE/T&R operation?
DS21S07AE/T&R requires a 4.7µF tantalum capacitor between VREF1 and VREF2 (pins 9 and 19) and ground, plus either a 2.2µF or 4.7µF capacitor on each TERMPWR pin (pins 1 and 11). A 0.1µF high-frequency bypass capacitor may be added in parallel with the 4.7µF VREF capacitor for systems using fast-rise-time drivers to suppress switching noise.
DS21S07AE/T&R Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- 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/T&R FAQ
1.How can I place an order for DS21S07AE/T&R through Aetrix?
Please submit a Request for Quotation (RFQ) for DS21S07AE/T&R 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/T&R reliable?
The price and inventory of DS21S07AE/T&R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS21S07AE/T&R is usually 5 days.
3.What payment methods are accepted for DS21S07AE/T&R?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS21S07AE/T&R transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS21S07AE/T&R?
DS21S07AE/T&R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS21S07AE/T&R 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/T&R?
For technical support, including DS21S07AE/T&R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS21S07AE/T&R requirements.
6.How does Aetrix verify that DS21S07AE/T&R is sourced from the original manufacturer or authorized distributors?
All DS21S07AE/T&R 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/T&R meets industry standards.
7.What is the process for return or replacement of DS21S07AE/T&R?
All DS21S07AE/T&R units undergo pre-shipment inspection (PSI). If there is an issue with DS21S07AE/T&R, 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/T&R part is unused and in its original packaging.
Return procedure for DS21S07AE/T&R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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