LT1512
3
1512fc
For more information www.linear.com/LT1512
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: Commercial devices are guaranteed over 0°C to 125°C junction
temperature range and 0°C to 70°C ambient temperature range. These
parts are also designed, characterized and expected to operate over the
–20°C to 85°C extended ambient temperature range, but are not tested at
–20°C or 85°C. Devices with full guaranteed electrical specifications over
the ambient temperature range –40°C to 85°C are available as industrial
parts with an “I” suffix.
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 5V, V
C
= 0.6V, V
FB
= V
REF
, I
FB
= 0V, V
SW
and S/S pins open,
unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IREF
I
FB
Reference Voltage Measured at I
FB
Pin
V
FB
= 0V, V
C
= 0.8V
l
–107
–110
–100
–100
–93
–90
mV
mV
I
FB
Input Current V
IFB
= V
IREF
(Note 3)
l
10 25 35 µA
I
FB
Reference Voltage Line Regulation 2.7V ≤ V
IN
≤ 25V, V
C
= 0.8V
l
0.01 0.05 %/V
g
m
Error Amplifier Transconductance
∆I
C
= ±25µA
l
1100
700
1500 1900
2300
µmho
µmho
Error Amplifier Source Current V
FB
= V
REF
– 150mV, V
C
= 1.5V
l
120 200 350 µA
Error Amplifier Sink Current V
FB
= V
REF
+ 150mV, V
C
= 1.5V
l
1400 2400 µA
Error Amplifier Clamp Voltage High Clamp, V
FB
= 1V
Low Clamp, V
FB
= 1.5V
1.70
0.25
1.95
0.40
2.30
0.52
V
V
A
V
Error Amplifier Voltage Gain 500 V/V
V
C
Pin Threshold Duty Cycle = 0% 0.8 1 1.25 V
f Switching Frequency 2.7V ≤ V
IN
≤ 25V
0°C ≤ T
J
≤ 125°C
–40°C ≤ T
J
< 0°C (LT1512I)
l
450
430
400
500
500
550
580
580
kHz
kHz
kHz
Maximum Switch Duty Cycle
l
85 95 %
Switch Current Limit Blanking Time 130 260 ns
BV Output Switch Breakdown Voltage 0°C ≤ T
J
≤ 125°C
–40°C ≤ T
J
< 20°C (LT1512I)
l
40
35
47 V
V
V
SAT
Output Switch ON Resistance I
SW
= 2A
l
0.5 0.8
I
LIM
Switch Current Limit Duty Cycle = 50%
Duty Cycle = 80% (Note 4)
l
l
1.5
1.3
1.9
1.7
2.7
2.5
A
A
∆
I
IN
∆I
SW
Supply Current Increase During Switch ON Time 15 25 mA/A
Control Voltage to Switch Current Transconductance 2 A/V
Minimum Input Voltage
l
2.4 2.7 V
I
Q
Supply Current 2.7V ≤ V
IN
≤ 25V
l
4 5.5 mA
Shutdown Supply Current 2.7V ≤ V
IN
≤ 25V, V
S/S
≤ 0.6V
0°C ≤ T
J
≤ 125°C
–40°C ≤ T
J
≤ 0°C (LT1512I)
l
12
30
50
µA
µA
Shutdown Threshold 2.7V ≤ V
IN
≤ 25V
l
0.6 1.3 2 V
Shutdown Delay
l
5 12 25 µs
S/S Pin Input Current 0V ≤ V
S/S
≤ 5V
l
–10 15 µA
Synchronization Frequency Range
l
600 800 kHz
Maximum allowable ambient temperature may be limited by power
dissipation. Parts may not necessarily be operated simultaneously
at maximum power dissipation and maximum ambient temperature.
Temperature rise calculations must be done as shown in the Applications
Information section to ensure that maximum junction temperature does
not exceed 125°C limit. With high power dissipation, maximum ambient
temperature may be less than 70°C.
Note 3: The I
FB
pin is servoed to its regulating state with V
C
= 0.8V.
Note 4: For duty cycles (DC) between 50% and 85%, minimum guaranteed
switch current is given by I
LIM
= 0.667 (2.75 – DC).
