Datasheet

3
LT1082
sn1082 1082fas
E
LECTR
IC
AL C CHARA TERIST
ICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
Q
Supply Current 3V ≤ V
IN
≤ V
MAX
, V
C
= 0.6V 4.5 7.0 mA
Control Pin Threshold Duty Cycle = 0 0.7 0.9 1.1 V
● 0.5 1.25 V
Normal/Flyback Threshold 0.58 0.67 0.8 V
on Feedback Pin
f Switching Frequency 50 60 70 kHz
● 45 75 kHz
800µA ≥ I
FB
≥ 450µA 12 kHz
BV Output Switch Breakdown Voltage 3V ≤ V
IN
≤ V
MAX
, I
SW
= 1.5mA ● 100 115 V
Control Voltage to Switch 1.5 A/V
Current Transconductance
V
FB
Flyback Reference Voltage I
FB
= 60µA 17 18.6 20.5 V
● 16 21.5 V
Change in Flyback Reference Voltage 60µA ≤ I
FB
≤ 200µA 3.5 4.6 6.5 V
Flyback Reference Voltage Line Regulation I
FB
= 60µA, 3V ≤ V
IN
≤ V
MAX
0.01 0.03 %/V
Flyback Amplifier Transconductance (g
m
) ∆I
C
= ±10µA 150 300 500 µmho
Flyback Amplifier Source V
C
= 0.6V Source ● 15 32 70 µA
and Sink Current I
FB
= 60µA Sink ● 30 50 90 µA
V
SAT
Output Switch “On” Resistance (Note 2) I
SW
= 0.7A (LT1082C), I
SW
= 0.5A (LT1082M) ● 0.8 1.2 Ω
I
LIM
Switch Current Limit Duty Cycle = 20% ● 1.07 2.6 A
(LT1082C) Duty Cycle ≤ 50%
● 1.0 2.6 A
Duty Cycle = 80% (Note 3) ● 0.8 2.4 A
Switch Current Limit Duty Cycle = 20%
● 0.85 2.8 A
(LT1082I) Duty Cycle ≤ 50%
● 0.8 2.8 A
Duty Cycle = 80% (Note 3) ● 0.65 2.6 A
Switch Current Limit Duty Cycle = 20%
● 0.75 3.0 A
(LT1082M) Duty Cycle ≤ 50%
● 0.7 3.0 A
Duty Cycle = 80% (Note 3) ● 0.6 2.8 A
∆I
IN
Supply Current Increase 35 45 mA/A
∆I
SW
During Switch-On Time
DC
MAX
Maximum Switch Duty Cycle 85 92 97 %
Flyback Sense Delay Time 1.5 µs
Shutdown Mode Supply Current 3V ≤ V
IN
≤ V
MAX
, V
C
= 0.05V 120 350 µA
Shutdown Mode 3V ≤ V
IN
≤ V
MAX
70 150 250 mV
Threshold Voltage ● 50 300 mV
Note 1: Absolute Maximum Ratings are those values beyond which the
life of a device may be impaired.
Note 2: Measured with V
C
in hi clamp, V
FB
= 0.8V.
Note 3: For duty cycles (DC) between 50% and 80%, minimum
guaranteed switch current decreases linearly.
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, V
C
= 0.5V, V
FB
= V
REF
, output pin open, unless otherwise
specified.