Texas Instruments UCC3918N, UCC3918DPTR, UCC3918DP Datasheet

Low On Resistance Hot Swap Power Manager

application

INFO

available

UCC2918
UCC3918

FEATURES

Integrated 0.06Ω Power

•

MOSFET

3V to 6V Operation

•

External Analog control of

•

Fault Current from 0A to 4A

Independent Analog Control

•

of Current Limit up to 5A

Fast Overload Protection

•

Uni-directional Switch

•

Minimal External Components

•

1µA I

•

Programmable On Time

•

• Programmable Start Delay

• Fixed 3% Duty Cycle

when Disabled

CC

DESCRIPTION

The UCC3918 Low on Resistance Hot Swap Power Manager provides complete
power management, hot swap capability, and circuit breaker functions. The only
components needed to operate the device, other than supply bypassing, are a tim
ing capacitor, and 2 programming resistors. All control and housekeeping functions
are integrated, and externally programmable. These include the fault current level,
maximum output sourcing current, maximum fault time, and startup delay. In the
event of a constant fault, the internal fixed 3% duty cycle ratio limits the average
output power. The IFAULT pin allows linear programming of the fault level current
from 0A to 4A.

Fast overload protection is accomplished by an additional overload comparator. Its
threshold is internally set above the maximum sourcing current limit setting. In the
event of a short circuit or extreme current condition, this comparator is tripped,
shutting down the output. This function is needed since the maximum sourcing cur
rent limit loop has a finite bandwidth.

When the output current is below the fault level, the output MOSFET is switched on
with a nominal resistance of 0.06Ω. When the output current exceeds the fault level
or the maximum sourcing level, the output remains on, but the fault timer starts
charging CT. Once CT charges to a preset threshold, the switch is turned off, and
remains off for 30 times the programmed fault time. When the output current
reaches the maximum sourcing level, the MOSFET transitions form a switch to a
constant current source.

-

-

BLOCK DIAGRAM

9

IMAX

FAULT LEVEL

IFAULT

8

COMPARATOR

+

MAXIMUM
CURRENT

LEVEL

CURRENT

OVERLOAD

OVERCURRENT

COMPARATOR

CHARGE

PUMP

REVERSE

COMPARATOR

ON TIME

CONTROL

3% DUTY

CYCLE

+

V

OUT

THERMAL

SHUTDOWN

INTERNAL

20mV

CURRENT SENSE

H = OPEN

BIAS

(continued)

VIN

1

VIN

2

VIN

3

14

VOUT

15

VOUT

16

VOUT

1.5V

+

–

7

SHTDWN

5

GND

SLUS384A - NOVEMBER 1999

4

13

HEAT SINK GND

PINS

12

10

6

FAU LTCT

UDG-99153

UCC2918
UCC3918

DESCRIPTION (continued)

The UCC3918 is designed for unidirectional current flow,
emulating an ideal diode in series with the power switch.
This feature is particularly attractive in applications where
many devices are powering a common bus, such as with
SCSI Termpwr. The UCC3918 can also be put into the
sleep mode, drawing only 1µA of supply current.

Other features include an open drain fault output indica

­tor, thermal shutdown, undervoltage lockout, 3V to 6V
operation, and a low thermal resistance small outline
power package.

ABSOLUTE MAXIMUM RATINGS

Input Supply Voltage (VIN) . . . . . . . . . . . . . . . . . . . . . . . . . . 8V

SOIC Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5W

Fault Output Sink Current. . . . . . . . . . . . . . . . . . . . . . . . . 50mA

Fault Output Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VIN

Output Current (DC) . . . . . . . . . . . . . . . . . . . . Internally Limited

Input Voltage

SHTDWN

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

Operating Junction Temperature Range . . . . –55°C to +150°C

Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C

Unless otherwise indicated, voltages are reference to ground
and currents are positive into, negative out of the specified
terminal. Pulsed is defined as a less than 10% duty cycle with a
maximum duration of 500
Databook for thermal limitations and considerations of package.

, IFAULT, IMAX . . . . . . . . . . . . . . . . . –0.3V to VIN

µ

S. Consult Packaging Section of

CONNECTION DIAGRAM

DIL-16, SOIC-16 (Top View)
N Package, DP Package

* Pin 5 serves as the lowest impedance to the electrical
ground. Pins 4, 12, and 13 serve as heat sink/ground.
These pins should be connected to large etch PCB areas
to help dissipate heat. For N Package, pins 4, 12, and 13
are N/C.

TSSOP-24 (Top View)
PWP Package

VIN

1

VIN

2

VIN

3

4

VIN

5

GND*

6

GND*

7

GND*

8

GND*

9

GND*

FAU LT

SHTDWN

IFAULT IMAX

10

11

12

24

VOUT

23

VOUT

22

VOUT

21

VOUT

20

GND*

19

GND*

18

GND*

17

GND*

GND*

16

15

N/C

1413CT

* Pin 9 serves as the lowest impedance to the electrical
ground. Pins 5, 6, 7, 8, 16, 17, 18, 19 and 20 serve as heat
sink/ground.

2

UCC2918
UCC3918

ELECTRICAL CHARACTERISTICS

UCC2918, VIN = 5V. R

IMAX

= 42.2k, R

: Unless otherwise specified, TA= 0°C to 70°C for the UCC3918, –40°C to 85° for the

= 52.3k, SHTDWN = 2.4. TA=TJ.

IFAULT

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

Supply Section

Voltage Input Range, VIN 356V

V

Supply Current No Load 1 2 mA

DD

Sleep Mode Current SHTDWN

= 0.2V 0.5 5 µA

Output Section

RDS

ON

Reverse Leakage Current V

I

= 1A to 4A, VIN = 5V, TA = 25°C 0.075 0.095 Ω

OUT

= 1A to 4A, VIN = 3V, TA = 25°C 0.09 0.116 Ω

I

OUT

= 1A to 4A, VIN = 5V 0.75 0.125 Ω

I

OUT

= 1A to 4A, VIN = 3V 0.09 0.154 Ω

I

OUT

= 0V, V

IN

= 5V, SHTDWN = 0V 20 A

OUT

Initial Startup Time (Note 1) 100 µS

Thermal Shutdown (Note 1) 170 DEG

Output Section (cont)

Thermal Hysteresis (Note 1) 10 DEG

Output Leakage SHTDWN

Trip Current R

Maximum Output Current R

IFAULT

R

IFAULT

R

IFAULT

R

IFAULT

IMAX

R

IMAX

R

IMAX

R

IMAX

R

IMAX

= 0.2V 20 µA

= 105k 0.75 1 1.25 A

= 52.3k 1.7 2 2.3 A

= 34.8k 2.5 3 3.5 A

= 25.5k 3.3 4 4.7 A

= 118k 0.3 1 1.7 A

= 60.4k 1 2 3 A

= 42.2k 2 3 4 A

= 33.2k 2.5 3.8 5.1 A

= 27.4k 3.0 4.6 6.2 A

Fault Section

C

Charge Current VCT= 1V –50 –36 –22 µA

T

Discharge Current VCT= 1V 0.5 1.2 2.0 µA

C

T

Fault Section (cont.)

Output Duty Cycle VOUT = 0V 1.5 3 6 %

Fault Threshold 0.8 1.3 1.8 V

C

T

Reset Threshold 0.25 0.5 0.75 V

C

T

Shutdown Section

Shutdown Threshold 1.1 1.5 2.0 V

Shutdown Hysteresis 100 mV

Input Low Current SHTDWN

Input High Current SHTDWN

= 0V –500 0 500 nA
= 2V –2 –1 –0.5 µA

Open Drain Fault Output

High Level Output Current 1 µA

Low Level Output Voltage I

= 1mA 0.4 0.9 V

OUT

Note 1: Guaranteed by design. Not 100% tested in production.

3