LTC3122
3
3122fa
For more information www.linear.com/LTC3122
elecTrical characTerisTics
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: Voltage transients on the SW pin beyond the DC limit specified in
the Absolute Maximum Ratings are non-disruptive to normal operations
when using good layout practices, as shown on the demo board or
described in the data sheet or application notes.
Note 3: The LTC3122 is tested under pulsed load conditions such that
T
A
≈ T
J
. The LTC3122E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 125°C operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC3122I is guaranteed
to meet specifications over the full –40°C to 125°C operating junction
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C (Note 3). V
IN
= 3.6V, V
OUT
= 12V, RT = 57.6k unless otherwise noted.
PARAMETER CONDITIONS MIN. TYP MAX UNITS
Minimum Start-Up Voltage V
OUT
= 0V
l
1.7 1.8 V
Input Voltage Range After V
OUT
≥ 2.2V
l
0.5 5.5 V
Output Voltage Adjust Range
l
2.2 15 V
Feedback Voltage
l
1.178 1.202 1.225 V
Feedback Input Current V
FB
= 1.4V 1 50 nA
Quiescent Current, Shutdown V
SD
= 0V, V
OUT
= 0V, Not Including Switch Leakage 0.01 1 µA
Quiescent Current, Active V
C
= 0V, Measured On V
IN
, Non-Switching 500 700 µA
Quiescent Current, Burst Measured on V
IN
, V
FB
> 1.4V
Measured on V
OUT
, V
FB
> 1.4V
25
10
40
20
µA
µA
N-channel MOSFET Switch Leakage Current V
SW
= 15V, V
OUT
= 15V, V
C
= 0V
l
0.1 30 µA
P-channel MOSFET Switch Leakage Current V
SW
= 0V, V
OUT
= 15V, V
SD
= 0V
l
0.1 70 µA
N-channel MOSFET Switch On-Resistance 0.121 Ω
P-channel MOSFET Switch On-Resistance 0.188 Ω
N-channel MOSFET Current Limit
l
2.5 3.5 4.5 A
Maximum Duty Cycle V
FB
= 1.0V
l
90 94 %
Minimum Duty Cycle V
FB
= 1.4V
l
0 %
Switching Frequency
l
0.85 1 1.15 MHz
SYNC Frequency Range
l
0.1 3 MHz
PWM/SYNC Input High
l
0.9 •V
CC
V
PWM/SYNC Input Low
l
0.1•V
CC
V
PWM/SYNC Input Current V
PWM/SYNC
= 5.5V 0.01 1 µA
CAP Clamp Voltage V
OUT
> 6.1V, Referenced to V
OUT
–5.2 –5.6 –6.0 V
V
CC
Regulation Voltage V
IN
< 2.8V, V
OUT
> 5V 4 4.25 4.5 V
Error Amplifier Transconductance
l
70 95 120 µS
Error Amplifier Output Current ±25 µA
Soft-Start Time 10 ms
SD Input High
l
1.6 V
SD Input Low
l
0.25 V
SD Input Current V
SD
= 5.5V 1 2 µA
temperature range. The LTC3122H is guaranteed to meet specifications
over the full –40°C to 150°C operating junction range. The junction
temperature (T
J
in °C) is calculated from the ambient temperature (T
A
in
°C) and power dissipation (P
D
in Watts) according to the formula: T
J
= T
A
+ (P
D
• θ
JA
) where θ
JA
is the thermal impedance of the package.
Note 4: The LTC3122 includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 150°C when overtemperature shutdown is active.
Continuous operation above the specified maximum operating junction
temperature may result in device degradation or failure.
Note 5: Failure to solder the exposed backside of the package to the PC
board ground plane will result in a thermal impedance much higher than
the rated package specifications.
