Micro Linear Corporation ML6599CT, ML6599CS Datasheet

February 1997

ML6599*

Hot-Insertable Active SCSI Terminator

GENERAL DESCRIPTION

The ML6599 BiCMOS 9 line SCSI terminator provides
active termination in SCSI systems using single ended
drivers and receivers. Active SCSI termination helps to
effectively control analog transmission line effects such as
ringing, noise, crosstalk, and ground bounce. In addition,
the ML6599 provides support for hot-insertability on the
SCSI bus.

The ML6599 provides a V-I characteristic optimized to
minimize transmission line effects during both signal
negation and assertion using a MOSFET-based
architecture. The desired V-I characteristic is achieved by
trimming one resistor in the control block. Internal
clamping controls signal assertion transients and provides
current sink capability to handle active negation driver
overshoots above 2.85V. It provides a 2.85V reference
through an internal low dropout (1V) linear regulator.

The ML6599 also provides a disconnect function which
effectively removes the terminator from the SCSI bus. The
disconnect mode capacitance is typically less than 5pF

FEATURES

■ Fully monolithic IC solution providing active

termination for 9 lines of the SCSI bus

■ Provides on board support for hot-insertability on the

SCSI bus

■ Low dropout voltage (1V) linear regulator, trimmed for

accurate termination current

■ Output capacitance typically < 5pF

■ Disconnect mode — logic pin to disconnect terminator

from the SCSI bus, <100µA

■ Current sinking — can sink current in excess of 10mA

per line to handle active negation driver overshoots
above 2.85V

■ Negative clamping on all lines to handle signal

assertion transients

■ Regulator can source 200mA and sink 100mA while

maintaining regulation

■ Current limit & thermal shutdown protection

per line. Current limiting and thermal shutdown
protection are also included. *Some Packages Are Obsolete

BLOCK DIAGRAM

GND

NCLAMP = Negative Clamp

NCLAMP

. . .

NCLAMP

NCLAMP

TERMPWR

LINEAR

REGULATOR

1V DROPOUT

MOSFETs WITH I

9 TERMINATION LINES

. . .

L2 L9L1

2.85V

MAX

. . .

= 24mA

R

TRIM

DISCNKT

2.85V

V

REF

CONTROL

BLOCK

V

REF

. . .

. . .

1

ML6599

PIN CONFIGURATION

20-Pin TSSOP16-Pin SOIC

TERMPWR

NC

NC

GND

DISCNKT

NC

1

2

3

4

5

6

L1

L2

7

8

16

15

14

13

12

11

10

9

L9

L8

L7

V

REF

L6

L5

L4

L3

PIN DESCRIPTION

NAME DESCRIPTION

TERMPWR Termination Power. Should be connected

to the SCSI TERMPWR line. A 10µF

tantalum local bypass capacitor is
recommended per system, as shown in
the application diagram

L1 Signal Termination 1. SCSI Bus line 1

L2 Signal Termination 2. SCSI Bus line 2

L3 Signal Termination 3. SCSI Bus line 3

L4 Signal Termination 4. SCSI Bus line 4

L5 Signal Termination 5. SCSI Bus line 5

L6 Signal Termination 6. SCSI Bus line 6

L7 Signal Termination 7. SCSI Bus line 7

L8 Signal Termination 8. SCSI Bus line 8

L9 Signal Termination 9. SCSI Bus line 9

TERMPWR

NC

GND

NC

DISCNKT

NC

HS

HS

1

2

3

4

5

6

7

8

L1

L2

9

10

20

19

18

17

16

15

14

13

12

11

L9

L8

HS

L7

V

L6

L5

L4

HS

L3

REF

NAME DESCRIPTION

V

REF

2.85V

Output. External decoupling

REF

with a 10µF tantalum in parallel with a

0.1µF ceramic capacitor is

recommended, as shown in the
application diagram.

DISCNKT Disconnect Terminator. Logic input to

disconnect the terminator from the bus
when the SCSI device no longer needs
termination due to not being the last
device on the bus or otherwise. Active
low input.

GND Ground. Signal ground (0V)

HS Heat Sink Ground. Should be

connected to GND.

NOTE : The DISCNKT line has a 200kΩ internal pullup resistor connected to the

supply. This pin should be left floating for normal operation and should
be connected to ground to enable the function.

2

ML6599

ABSOLUTE MAXIMUM RATINGS

Signal Line Voltage .................. –0.3 to TERMPWR + 0.3V

Regulator Output Current ......................... –100 to 300mA

OPERATING CONDITIONS

TERMPWR Voltage ........................................ 4V to 5.25V

Operating Temperature ................................. 0°C to 70°C

TERMPWR Voltage ........................................... –0.3 to 7V

Storage Temperature................................. –65°C to 150°C

Soldering Temperature ................................ 260°C for 10s

Thermal Impedance (θ

)

JA

SOIC ................................................................ 95°C/W

TSSOP ............................................................ 110°C/W

ELECTRICAL CHARACTERISTICS

Unless otherwise stated, these specifications apply for 4V ≤ TERMPWR ≤ 5.25V, and TA = 0°C to 70°C (Note 1)

PARAMETER CONDITIONS MIN TYP MAX UNITS

Supply

TERMPWR Supply Current L1–L9 = open, DISCNKT = open 4.5 5.5 mA

L1–L9 = 0.2 V, DISCNKT = open 225 250 mA

Disconnect Mode Current DISCNKT = 0 (active) 75 100 µA

DISCNKT

Input Low Voltage 1.0 V

Input High Voltage TERMPWR – 1.0 V

Output

Output High Voltage Measuring each signal line 2.8 2.85 2.9 V

while other eight are high

Output Current V
(Normal Mode) line while the other eight are high

Hot Insertion Peak Current TERMPWR = 0V, V

Output Clamp Level I

Sinking Current (per line) V

Output Capacitance L1 thru L9, DISCNKT = 0 4 5 pF
(Micro Linear Method) 2V

Output Capacitance L1 thru L9, DISCNKT = 0 6 7 pF
(X3T9.2/855D method) 0.4V

Regulator

Output Voltage Sourcing 0-200mA 2.8 2.85 2.9 V

Sinking Current V = 3.5V 125 150 mA

Short Circuit Current V

Dropout Voltage L1–L9 = 0.2V 1.0 1.2 V

Thermal Shutdown 170 °C

= 0.2V, Measuring each signal 20 24 mA

OUT

= 0V 1 2 µA

Any signal line (L1–L9) at 2.85V

= –30mA (Note 2) –0.15 0 0.15 V

OUT

= 3.3V (per line) 10 12 mA

OUT

100kHz square wave

P-P

applied biased at 1V D.C.

, 1MHz square wave

P-P

applied biased at 0.5V D.C.

Sinking 0-100mA 2.8 2.85 2.9 V

= 0V 150 mA

REF

V

= 5V 300 mA

REF

REF

Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst case test conditions.

3