MAXIM DS2125 Technical data

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Ultra3 LVD/SE SCSI 15-Line Terminato

www.maxim-ic.com

GENERAL DESCRIPTION

The DS2125 Ultra3 LVD/SE SCSI terminator is both a low-voltage differential (LVD) and single-ended (SE) terminator. The multimode operation enables the designer to implement LVD in current products while allowing the end user SE backward compatibility with legacy devices. If the device is connected in an LVD-only bus, the DS2125 uses LVD termination. If any SE devices are connected to the bus, the DS2125 uses SE termination, which is accomplished automatically inside the part by sensing the voltage on the SCSI bus DIFFSENS line.

For the LVD termination, the DS2125 integrates two current sources with 15 precision resistor strings. For the SE termination, one regulator and 15 precision 110W resistors are used. Two DS2125 terminators are needed for a wide SCSI bus.

APPLICATIONS

Raid Systems SCSI Host Bus Adapter (HBA) Cards Servers SCSI Cables Network Attached Storage (NAS) Storage Area Networks (SANs)

ORDERING INFORMATION

PART TEMP RANGE PIN-PACKAGE

DS2125 0°C to +70°C 48 LQFP

DS2125

FEATURES

§ Fully Compliant with Ultra3 SCSI

§ Provides Multimode Low-Voltage

Differential/Single-Ended (LVD/SE) Termination for 15 Signal Line Pairs

§ Auto-Selection of LVD or SE Termination

§ 5% Tolerance on SE and LVD Termination

Resistance

§ Low 3pF Power-Down Capacitance

§ On-Board Thermal-Shutdown Circuitry

§ SCSI Bus Hot-Plug Compatible

§ Fully Supports Actively Negated SE SCSI

R1P R1N

R2P

R2N

R3P

R3N

R4P

R4N

R5P

R5N

R6P

R6N

R7P

R7N

R8P R8N

GND

REF

101112

25 26 27 28 29 30

Semiconductor

Dallas

DS2125

31 32 33 34 35 36

LQFP

3 4 5 6 7 8

Signals

PIN CONFIGURATION

TOP VIEW

HS_GND HS_GND HS_GND

HS_GND HS_GND HS_GND TPWR R15N R15P

R14N

R14P

R13N

R13P

R12N

R12P

R11N

R11P

R10N

R10P

R9N

R9P

ISO DIFFSENSE DIFF_CAP HS_GND HS_GND HS_GND

Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device may be simultaneously available through various sales channels. For information about device errata, click here: www.maxim-ic.com/errata

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REV: 052604

DS2125 Ultra3 LVD/SE SCSI 15-Line Terminator

ABSOLUTE MAXIMUM RATINGS

, ISO, GND, DIFFSENSE, DIFF_CAP, TPWR, RxP, RxN (x = 1 . . . 15) -0.3V, +6.0V

REF

Continuous Output Current ±200mA

REF

Continuous Power Dissipation (T

= +70°C), 48-Pin LQFP

2W Operating Temperature Range 0°C to +70°C Junction Temperature +150°C Storage Temperature Range -65°C to +160°C Lead Temperature (soldering, 10s) +300°C

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to the absolute maximum rating conditions for extended periods may affect device reliability.

ELECTRICAL CHARACTERISTICS

(TPWR = 3.3V, TA = 0°C to +70°C, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

TPWR Operating Supply Range

TPWR

LVD SE

TPWR SUPPLY CURRENT

TPWR Supply Current (All Lines Open)

TPWR_LVD

TPWR_SE

TPWR_ISO

LVD SCSI mode

SE SCSI mode

ISO mode (terminators disabled) LVD TERMINATION (Applies to each line pair, 1 to 15 in LVD mode) Differential-Mode Termination Resistance Common-Mode Termination Resistance

100 110

RP and RN shorted together 110 165

Differential-Mode Bias VDM All lines open 100 125 mV Common-Mode Bias VCM RP and RN shorted together 1.15 1.25 1.35 V SE TERMINATION (Applies to SE terminators, 1 to 15 in SE mode)

= (VLx - 0.2) / ILx,

Single-Ended Mode Termination Resistance

where V

pin with pin unloaded and

= current for each terminator pin

= voltage at terminator

with the pin forced to 0.2V (Note 2)

(Note 2)

SE Voltage Reference V

REF

Signal level at 0.5V -18.0 -22.4

(Note 2) 2.7 2.85 3.0 V

Signal level at 0.2V, all lines low -21.0 -24 -25.4 Termination Current

Pin Leakage With ISO high 400 nA

Single-Ended GND Resistance

Measured at RP pins, I = 10mA 20 60

GND

TERMINATOR PIN CAPACITANCE

Terminator Pin Capacitance

REGULATOR

REF

1.25V Regulator Output Voltage

1.25V Regulator ShortCircuit Source Current

1.25V Regulator ShortCircuit Sink Current

1.25V Regulator Line Regulation

With ISO high (Note 1) 3 pF

1.15 1.25 1.35 V

REF_LVD

SOURCE

SINK

= 0V -375 -700 -1000 mA

REF

= 3.3V 170 300 700 mA

REF

unloaded; vary TPWR from

REF

2.7V to 5.5V

2.85V Regulator (Note 2) 2.7 2.85 3.0 V

2.85V Regulator ShortCircuit Source Current

2.85V Regulator ShortCircuit Sink Current

= 0V (Note 2) -375 -700 -1000 mA

REF

= 3.3V (Note 2) 170 300 700 mA

REF

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2.7 5.5

4.0 5.5

20 32

1.6 10 250 750

mA mA

104.5 110 115.5

1.0 2.5

DS2125 Ultra3 LVD/SE SCSI 15-Line Terminator

ELECTRICAL CHARACTERISTICS (continued)

(TPWR = 3.3V, TA = 0°C to +70°C, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

REGULATOR

REF

2.85V Regulator Line Regulation

unloaded; vary TPWR from

REF

4.0V to 5.5V

1.0 2.5

DIFFSENS OUTPUT

DIFFSENS Driver Output Voltage DIFFSENS Driver Source Current DIFFSENS Driver Sink Current

DIFFSENS Leakage (Note 3)

DSO

DSH

DSL

LEAK, LOW

LEAK, HIGH

-5mA £ I

DIFFSENS

DFFSENS

= 0V -15 -5 mA

= 3.3V 100 200

With ISO high, |V

0.3V

£ 50mA

DIFFSENS

| = 0.3V -3 +1

- V

TPWR

| =

1.2 1.4 V

1 3

THERMAL SHUTDOWN

Thermal-Shutdown Threshold Thermal-Shutdown Hysteresis

(Note 1) 10

For increasing temperature (Note 1)

150

°C

MODE CHANGE DELAY/FILTER

Mode Change Delay t

0.66 1.25 2.00 ms

DELAY

LOGICAL SIGNALS (ISO)

Input Low Voltage VIL -0.3 +0.8 V

Input High Voltage VIH 2

Input Current IIL VCC = 3.3V -30 -10

TPWR

+ 0.3

DIFF_CAP

Input Current IL V DIFF_CAP SE

Operating Range DIFF_CAP LVD Operating Range DIFF_CAP HVD Operating Range

Note 1: Guaranteed by design. Note 2: TPWR = 4.0V. Note 3: Room temperature only.

-0.3 +0.5 V

SEOR

0.7 1.9 V

LVDOR

2.4

HVDOR

= -0.3V -1 +1

TPWR

0.3

PIN DESCRIPTION

PIN NAME FUNCTION

1, 2, 11–26,

37–48

3 TPWR

4–9, 28–33 HS_GND Heat-Sink Ground. Internally connected to the mounting pad. This should be grounded.

10 V

27 GND Ground. Signal ground, 0V.

34 DIFF_CAP

35 DIFFSENSE DIFFSENSE. Output to drive the SCSI bus DIFFSENS line.

RxP, RxN Signal Termination. Connect to SCSI bus signal lines.

Termination Power. Connect to the SCSI TERMPWR line and decouple with a 2.2mF capacitor.

REF

decoupled with a 4.7mF capacitor.

Reference Voltage. 2.85V reference in SE mode and 1.25V reference in LVD mode; must be

DIFFSENSE Capacitor. Connect a 0.1mF capacitor for the DIFFSENSE filter. Input to detect the type of device (differential or single-ended) on the SCSI bus.

36 ISO Isolation. When pulled high, the DS2125 isolates its bus pins (RxN, RxP) from the SCSI bus.

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