PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

Fault Section

CT Charge Current

–50

–36

–22

µA

CT Discharge Current

0.36

0.6

1

µA

Output Duty Cycle

VOUT = 0V

1

2

4

%

CT Fault Threshold

Note 2

1.25

1.5

1.75

V

CT Reset Threshold

Note 2

0.25

0.5

0.75

V

Shutdown Section

Shutdown Threshold

1.1

1.5

1.9

V

Shutdown Hysterisis

50

mV

Open Drain Fault Output

High Level Output Current

1

µA

Low Level Output Voltage

IOUT = 2mA

0.4

V

IOUT = 10mA

0.9

V

Logic Input DC Characteristics

Input Voltage High

2V

Input Voltage Low

0.8

V

Input High Current

VIH = 2.4V

3

10

µA

Input Low Current

VIL = 0.4V

1

µA

UCC2920

UCC3920

PIN DESCRIPTIONS

BO - B2: These pins provide a digital input to the DAC.

They can be used to provide a digital soft start, adaptive

current limiting, or be strapped for static applications.

CT: A capacitor connected to CT sets the maximum fault

time. The maximum must be more than the time to charge

external load capacitance. The maximum fault time is

reached the output will shutdown for a time given by: TSD

= 1.67

FAULT: Open drain output which, pulls low, from VDD to

GND, upon any condition which causes the output to

open: Fault, Thermal Shutdown, or Shutdown.

GND: Reference return for VDD and VSS (VIN). This

serves as the reference point for digital signals.

IMAX: When this pin is at a logic low the linear output

current will always be 1A above the programmed trip

level, and with a logic high the linear current will always

be a constant 4A for applications which require fast

charging of load capacitance.

SHTDWN: When this pin is brought down low the IC is

put into a sleep mode.

VDD: Positive input voltage to the circuit breaker. The

input voltage range is 3V to 5.5V. If the total voltage

excursion, VDD - VSS could be 15V or greater, VDD

should have an external limiting resistor in series with it.

VSS: The input voltage to the circuit breaker. The

recommended voltage range is –3.3V to –15V.

VOUT: Output voltage for the circuit breaker. When

switched the output voltage will be approximately VIN +

0.1

Ω • IOUT.

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

Note 2: Voltages measured with respect to VSS.

Note 3: An external resistor in series with VDD could be used to limit the current to 10mA if an input voltage higher than 15V is de-

sired.

3