Datasheet

UCC28070
SLUS794E –NOVEMBER 2007–REVISED APRIL 2011 www.ti.com
ELECTRICAL CHARACTERISTICS
over operating free-air temperature range −40°C < T
A
< 125°C, T
J
= T
A
, VCC = 12 V, GND = 0 V, R
RT
= 75 kΩ, R
DMX
= 68.1
kΩ, R
RDM
= R
SYN
= 100 kΩ, C
CDR
= 2.2 nF, C
SS
= C
VREF
= 0.1 μF, C
VCC
= 1 μF, I
VREF
= 0 mA (unless otherwise noted)
SYMBOL PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
Bias Supply
VCC
SHUNT
VCC shunt voltage
(1)
I
VCC
= 10 mA 23 25 27 V
VCC current, disabled VSENSE = 0 V 7
mA
VCC current, enabled VSENSE = 3 V (switching) 9 12
VCC = 7 V 200 μA
VCC current, UVLO
VCC = 9 V 4 6 mA
V
UVLO
UVLO turn-on threshold Measured at VCC (rising) 9.8 10.2 10.6
UVLO hysteresis Measured at VCC (falling) 1 V
VREF enable threshold Measured at VCC (rising) 7.5 8 8.5
Linear Regulator
VREF voltage, no load I
VREF
= 0 mA 5.82 6 6.18 V
Measured as the change in VREF,
VREF load rejection -12 12
(I
VREF
= 0 mA and −2 mA)
mV
Measured as the change in VREF,
VREF line rejection -12 12
(VCC = 11V and 20 V, I
VREF
= 0 μA)
PFC Enable
V
EN
Enable threshold Measured at VSENSE (rising) 0.65 0.75 0.85
V
Enable hysteresis 0.15
External PFC Disable
Disable threshold Measured at SS (falling) 0.5 0.6
V
Hysteresis VSENSE > 0.85 V 0.15
Oscillator
Output phase shift Measured between GDA and GDB 179 180 181 Degree
V
DMAX
,V
RT
,
Timing regulation voltages Measured at DMAX, RT, & RDM 2.91 3 3.09 V
and V
RDM
R
RT
= 75 kΩ, R
DMX
= 68.1 kΩ,
95 100 105
V
RDM
= 0 V, V
CDR
= 6 V
f
PWM
PWM switching frequency kHz
R
RT
= 24.9 kΩ, R
DMX
= 22.6 kΩ,
270 290 330
V
RDM
= 0 V, V
CDR
= 6 V
R
RT
= 75 kΩ, R
DMX
= 68.1 kΩ,
D
MAX
Duty-cycle clamp 92% 95% 98%
V
RDM
= 0 V, V
CDR
= 6 V
R
RT
= 24.9 kΩ, R
DMX
= 22.6 kΩ,
Minimum programmable off-time 50 150 250 ns
V
RDM
= 0 V, V
CDR
= 6 V
R
RDM
= 316 kΩ, R
RT
= 75 kΩ 2 3 4
Frequency dithering magnitude change
f
DM
in f
PWM
R
RDM
= 31.6 kΩ, R
RT
= 24.9 kΩ 24 30 36
kHz
C
CDR
= 2.2 nF, R
RDM
= 100 kΩ 3
Frequency dithering rate rate of
f
DR
change in f
PWM
C
CDR
= 0.3 nF, R
RDM
= 100 kΩ 20
Dither rate current Measure at CDR (sink and source) ±10 μA
I
CDR
Dither disable threshold Measured at C
CDR
(rising) 5 5.25 V
(1) Excessive VCC input voltage and/or current damages the device. This clamp will not protect the device from an unregulated supply. If
an unregulated supply is used, a series-connected fixed positive voltage regulator such as a UA78L15A is recommended. See the
Absolute Maximum Ratings section for the limits on VCC voltage and current.
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