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
Oscillator Section
TEST CONDITIONS
MIN
TYP
MAX UNITS
Synchronizable Frequency (See Note 2.)
BUCK = VBAT– 2, VBAT = 12V to 25V,
80
80
-
-
160
145
kHz
kHz
T
A = –40°C to +85°C
BUCK = VBAT–2, VBAT = 12V to 25V
A = –55°C to +125°C
T
Maximum Duty Cycle
FB = 1V, TA < 0°C
FB = 1V, TA = 0°C to 70°C
FB = 2V
84
90
%
%
95
Minimum Duty Cycle
0
%
BUCK Input Bias Current
BUCK = VBAT = 12V
BUCK = VBAT = 25V
40
80
–1
90
mA
mA
V
110
–0.3
Zero Detect Threshold
Measured at BUCK w/respect to VBAT,
VBAT=12V to 25V, TA < 0°C
–2.4
–2.0
Measured at BUCK w/respect to VBAT,
VBAT=12V to 25V, TA = 0°C to 70°C
–1
–0.3
V
Error Amplifier
Input Voltage
COMP = 2V, TA = 0°C to +70°C
1.465
1.455
–2
1.5
2
1.535
1.545
10
V
V
COMP = 2V
Line Regulation
mV
nA
dB
V
Input Bias Current
–500 –100
Open Loop Gain
COMP = 0.5V to 3.0V
FB = 1V
60
80
3.7
0.15
–1.2
4
Output High Voltage
Output Low Voltage
Output Source Current
Output Sink Current
Output Source Current
Output Sink Current
Unity Gain Bandwidth
Mode Select
3.3
4.1
FB = 2V
0.35
–0.4
V
FB = 1V, COMP = 2V
FB = 2V, COMP = 2V
FB = 1V, COMP = 2V, MODE = 0.5V
FB = 2V, COMP = 2V, MODE = 0.5V
TJ = 25C, Note 1
mA
mA
mA
mA
MHz
2
–1
–1
1
1
2
Output Enable Threshold
Open Lamp Detect Enable Threshold
Mode Output Current
MODE Clamp Voltage
Open Lamp
0.85
2.75
15
1
3
1.15
3.25
25
V
V
MODE = 0.5V
20
3.7
mA
V
MODE = OPEN
3.3
4
Open Lamp Detect Threshold
Measured at BUCK with respect to VBAT,
VBAT=12V to 25V
–8
–7
–9
–6
V
V
Over-voltage Clamp Threshold (UCC3973) Measured at BUCK with respect to VBAT,
–10.3
–7.7
VBAT=12V to 25V, IFB = 100µA
Note 1. Ensured by design. Not 100% tested in production.
Note 2. Oscillator operates at 2x transformer switching frequencey.
3
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