3

UCC1972/3

UCC2972/3

UCC3972/3

ELECTRICAL CHARACTERISTICS:Unless otherwise specified these specifications hold for TA=0°C to +70°C for the

UC3972/3, –40°C to +85°C for the UC2972/3, and –55°C to +125°C for the UC1972/3; TA=TJ; VDD=VBAT=VBUCK=12V;

MODE=OPEN. For any tests with VBAT>17V, place a 1k resistor from VBAT to VDD.

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

Oscillator Section

Synchronizable Frequency (See Note 2.)

BUCK = VBAT– 2, VBAT = 12V to 25V,

TA = –40°C to +85°C

80

-

160

kHz

BUCK = VBAT–2, VBAT = 12V to 25V

TA = –55°C to +125°C

80

-

145

kHz

Maximum Duty Cycle

FB = 1V, TA < 0°C

84

%

FB = 1V, TA = 0°C to 70°C

90

95

%

Minimum Duty Cycle

FB = 2V

0

%

BUCK Input Bias Current

BUCK = VBAT = 12V

40

90

mA

BUCK = VBAT = 25V

80

110

mA

Zero Detect Threshold

Measured at BUCK w/respect to VBAT,

VBAT=12V to 25V, TA < 0°C

–2.4

–1

–0.3

V

Measured at BUCK w/respect to VBAT,

VBAT=12V to 25V, TA = 0°C to 70°C

–2.0

–1

–0.3

V

Error Amplifier

Input Voltage

COMP = 2V, TA =0°Cto+70°C

1.465

1.5

1.535

V

COMP = 2V

1.455

1.545

V

Line Regulation

–2

2

10

mV

Input Bias Current

–500

–100

nA

Open Loop Gain

COMP = 0.5V to 3.0V

60

80

dB

Output High Voltage

FB = 1V

3.3

3.7

4.1

V

Output Low Voltage

FB = 2V

0.15

0.35

V

Output Source Current

FB = 1V, COMP = 2V

–1.2

–0.4

mA

Output Sink Current

FB = 2V, COMP = 2V

2

4

mA

Output Source Current

FB = 1V, COMP = 2V, MODE = 0.5V

–1

1

mA

Output Sink Current

FB = 2V, COMP = 2V, MODE = 0.5V

–1

1

mA

Unity Gain Bandwidth

TJ = 25C, Note 1

2

MHz

Mode Select

Output Enable Threshold

0.85

1

1.15

V

Open Lamp Detect Enable Threshold

2.75

3

3.25

V

Mode Output Current

MODE = 0.5V

15

20

25

mA

MODE Clamp Voltage

MODE = OPEN

3.3

3.7

4

V

Open Lamp

Open Lamp Detect Threshold

Measured at BUCK with respect to VBAT,

VBAT=12V to 25V

–8

–7

–6

V

Over-voltage Clamp Threshold (UCC3973) Measured at BUCK with respect to VBAT,

VBAT=12V to 25V, IFB = 100µA

–10.3

–9

–7.7

V

Note 1. Ensured by design. Not 100% tested in production.

Note 2. Oscillator operates at 2x transformer switching frequencey.