UNITRODE UCC1913, UCC2913, UCC3913 Technical data

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Negative Voltage Hot Swap Power Manager

UCC1913
UCC2913
UCC3913

FEATURES

• Precision Fault Threshold

• Programmable Average Power

Limiting

• Programmable Linear Current Control

• Programmable

• Overcurrent Limit

• Programmable Fault Time

• Fault Output Indication

• Shutdown Control

• Undervoltage Lockout

• 8-Pin SOIC

DESCRIPTION

The UCC1913 family of negative voltage circuit breakers provides com­plete power management, hot swap, and fault handling capability. The IC is
referenced to the negative input voltage and is driven through an external
resistor connected to ground, which is essentially a current drive as op­posed to the traditional voltage drive. The on-board 10V shunt regulator
protects the IC from excess voltage and serves as a reference for program­ming the maximum allowable output sourcing current during a fault. All
control and housekeeping functions are integrated, and externally program­mable. These include the fault current level, maximum output sourcing cur­rent, maximum fault time, soft start time, and average power limiting. In the
event of a constant fault, the internal timer will limit the on-time from less
than 0.1% to a maximum of 3%. The duty cycle modulates depending on
the current into the PL pin, which is a function of the voltage across the
FET, and will limit average power dissipation in the FET. The fault level is
fixed at 50mV across the current sense amplifier to minimize total dropout.
The fault current level is set with an external current sense resistor. The
maximum allowable sourcing current is programmed with a voltage divider
from VDD to generate a fixed voltage on the IMAX pin. The current level,
when the output appears as a current source, is equal to V

IMAX/RSENSE

desired, a controlled current startup can be programmed with a capacitor
on the IMAX pin.

When the output current is below the fault level, the output device is
switched on. When the output current exceeds the fault level, but is less
than the maximum sourcing level programmed by the IMAX pin, the output
remains switched on, and the fault timer starts charging CT. Once CT
charges to 2.5V, the output device is turned off and performs a retry some
time later. When the output current reaches the maximum sourcing current
level, the output appears as a current source, limiting the output current to
the set value defined by IMAX.

.If

BLOCK DIAGRAM

LOGIC

SUPPLY

9.5V SHUNT REGULATOR

SD/FLT

SLUS274 - JANUARY 1999

1

20µA

Other features of the UCC1913 family include undervoltage lockout, and
8-pin small outline (SOIC) and Dual-In-Line (DIL) packages.

VDD

3

5.0V
REF

V

DD

SOURCE

ONLY

UVLO

1=
UNDERVOLTAGE

OVERLOAD COMPARATOR

ON-TIME

CONTROL

0.2V
+

IMAX

2

V

DD

DISABLE

OVERCURRENT
COMPARATOR

5.0V

LINEAR
CURRENT
AMPLIFIER

+

50mV

50Ω

V

DD

8

PL

7OUT

6 SENSE

5 VSS

4CT

UDG-99001

ABSOLUTE MAXIMUM RATINGS

I

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50mA

VCC

SHUTDOWN Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10mA

PL Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10mA

IMAX Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VCC

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

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

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

All voltages are with respect to VSS (The most negative volt­age). All currents are positive into, negative out of the specified
terminal. Consult Packaging Section of Databook for thermal
limitations and considerations of packages.

CONNECTION DIAGRAMS

DIL-8, SOIC-8 (Top View)
N or J, D Package

SD/FLT

IMAX

VDD

CT

1

2

3

4

8

7

6

5

UCC1913
UCC2913
UCC3913

PL

OUT

SENSE

VSS

ELECTRICAL CHARACTERISTICS: Unless otherwise stated these specifications apply for T

UCC1913; –40°C to +85°C for UCC2913; 0°C to +70°C for UCC3913; I

= 2mA, CT = 4.7pF, TA= T

VDD

= –55°C to +125°C for

A

J

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

VDD Section

IDD 1.0 2.0 mA
Regulator Voltage I

SOURCE

= 2mA to 10mA 8.5 9.5 10.5 V

UVLO Off Voltage 678V

Fault Timing Section

Overcurrent Threshold T

= 25°C 47.5 50 53 mV

J

Over Operating Temperature 46 50 53.5 mV
Overcurrent Input Bias 50 500 nA
CT Charge Current VCT= 1.0V, IPL= 0 –50 –36 –22 µA

Overload Condition, V

SENSE

– V

= 300mV –1.7 –1.2 –0.7 mA

IMAX

CT Discharge Current VCT= 1.0V, IPL= 0 0.6 1 1.5 µA
CT Fault Threshold 2.2 2.4 2.6 V
CT Reset Threshold 0.32 0.5 0.62 V
Output Duty Cycle Fault Condition, IPL= 0 1.7 2.7 3.7 %

Output Section

Output High Voltage I

Outut Low Voltage I

= 0A 8.5 10 V

OUT

I

= –1mA 6 8 V

OUT
OUT

I

OUT

= 0A; V
= 2mA; V

SENSE

SENSE

– V

= 100mV 0 0.01 V

IMAX

– V

= 100mV 0.2 0.6 V

IMAX

Linear Amplifier Section

Sense Control Voltage IMAX = 100mV 85 100 115 mV

IMAX = 400mV 370 400 430 mV
Input Bias 50 500 nA

Shutdown/Fault Section

Shutdown Threshold 1.4 1.7 2.0 V
Input Current Shutdown = 5V 15 25 45 µA
Fault Output High 6 7.5 9 V
Fault Output Low 0 0.01 V
Delay to Output (Note 1) 150 300 ns

2

UCC1913
UCC2913
UCC3913

ELECTRICAL CHARACTERISTICS:

UCC1913; –40°C to +85°C for UCC2913; 0°C to +70°C for UCC3913; I

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

Power Limiting Section

V
Duty Cycle Control IPL= 64µA 0.6 1.2 1.7 %

Overload Section

Delay to Output (Note 1) 300 500 ns
Output Sink Current V
Threshold Relative to IMAX 140 200 260 mV

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

Regulator Voltage IPL= 64 A 4.35 4.85 5.35 V

SENSE

Unless otherwise stated these specifications apply for TA= –55°C to +125°C for

= 2mA, CT = 4.7pF, TA= T

VDD

I

= 1mA 0.045 0.1 0.17 %

PL

SENSE

= V

= 300mV 40 100 mA

IMAX

J

PIN DESCRIPTIONS

CT: A capacitor is connected to this pin in order to set the

maximum fault time. The maximum fault time must be
more than the time to charge external load capacitance.
The maximum fault time is defined as:

()

CT

T

FAULT

•2

=

I

CH

where

IAI

=+36µ

CH PL

and I

is the current into the power limit pin. Once the

PL

,

fault time is reached the output will shutdown for a time
given by:

TCT

=• •2 106

SD

IMAX: This pin programs the maximum allowable sour­cing current. Since VDD is a regulated voltage, a voltage
divider can be derived from VDD to generate the pro­gram level for the IMAX pin. The current level at which
the output appears as a current source is equal to the
voltage on the IMAX pin over the current sense resistor.
If desired, a controlled current startup can be pro­grammed with a capacitor on the imax pin, and a pro­grammed start delay can be achieved by driving the
shutdown with an open collector/drain device into an RC
network.

OUT: Output drive to the MOSFET pass element.
PL: This feature ensures that the average MOSFET

power dissipation is controlled. A resistor is connected

from this pin to the drain of the NMOS pass element.
When the voltage across the NMOS exceeds 5V, current
will flow into the PL pin which adds to the fault timer
charge current, reducing the duty cycle from the 3%
level. When I

>>36µA then the average MOSFET

PL

power dissipation is given by:

−

PIMAX R

FET avg PL

=•••

()

110

6

SENSE: Input voltage from the current sense resistor.
When there is greater than 50mV across this pin with re­spect to VSS, then a fault is sensed, and CT starts to
charge.

SD/FLT: This pin provides fault output indication and
shutdown control. Interface into and out of this pin is usu­ally performed through level shift transistors. When 20µA
is sourced into this pin, shutdown drives high causing the
output to disable the NMOS pass device. When opened,
and under a non-fault condition, the SD/FLT pin will pull
to a low state. When a fault is detected by the fault timer,
or undervoltage lockout, this pin will drive to a high state,
indicating the output FET is off.

VDD: Current driven with a resistor to a voltage at least
10V more positive than VSS. Typically a resistor is con­nected to ground. The 10V shunt regulator clamps VDD
at 10V above the VSS pin, and is also used as an output
reference to program the maximum allowable sourcing
current.

VSS: Ground reference for the IC and the most negative
voltage available.

3