Datasheet

LTC4278
4
4278fc
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
PARAMETER CONDITIONS MIN TYP MAX UNITS
PWM Controller (Note 10)
Power Supply
V
CC
Operating Range
l
4.5 20 V
V
CC
Supply Current (I
CC
) V
CMP
= Open (Note 11)
l
4 6.4 10 mA
V
CC
Shutdown Current V
CMP
= Open, V
UVLO
= 0V
l
50 150 µA
Feedback Amplifier
Feedback Regulation Voltage (V
FB
)
l
1.220 1.237 1.251 V
Feedback Pin Input Bias Current R
CMP
Open 200 nA
Feedback Amplifier Transconductance ∆I
C
= ±10µA
l
700 1000 1400 µmho
Feedback Amplifier Source or Sink Current
l
25 55 90 µA
Feedback Amplifier Clamp Voltage V
FB
= 0.9V
V
FB
= 1.4V
2.56
0.84
V
V
Reference Voltage Line Regulation 12V ≤ V
CC
≤ 18V
l
0.005 0.05 %/V
Feedback Amplifier Voltage Gain V
CMP
= 1.2V to 1.7V 1400 V/ V
Soft-Start Charging Current V
SFST
= 1.5V 16 20 25 µA
Soft-Start Discharge Current V
SFST
= 1.5V, V
UVLO
= 0V 0.7 1.3 mA
Control Pin Threshold (V
CMP
) Duty Cycle = Min 1 V
Gate Outputs
PG, SG Output High Level
l
6.6 7.4 8 V
PG, SG Output Low Level
l
0.01 0.05 V
PG, SG Output Shutdown Strength
V
UVLO
= 0V; I
PG
, I
SG
= 20mA
l
1.6 2.3 V
PG Rise Time C
PG
= 1nF 11 ns
SG Rise Time C
SG
= 1nF 15 ns
PG, SG Fall Time C
PG
, C
SG
= 1nF 10 ns
Current Amplifier
Switch Current Limit at Maximum V
CMP
V
SENSE
+
l
88 98 110 mV
∆V
SENSE
/∆V
CMP
0.07 V/ V
Sense Voltage Overcurrent Fault Voltage V
SENSE
+
, V
SFST
< 1V
l
206 230 mV
Timing
Switching Frequency (f
OSC
) C
OSC
= 100pF
l
84 100 110 kHz
Oscillator Capacitor Value (C
OSC
) (Note 12) 33 200 pF
Minimum Switch On Time (t
ON(MIN)
) 200 ns
Flyback Enable Delay Time (t
ENDLY
) 265 ns
PG Turn-On Delay Time (t
PGDLY
) 200 ns
Maximum Switch Duty Cycle
l
85 88 %
SYNC Pin Threshold
l
1.53 2.1 V
SYNC Pin Input Resistance 40 kΩ