Datasheet

LTC3129
3
3129fa
For more information www.linear.com/LTC3129
elecTrical characTerisTics
The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). Unless otherwise noted, V
IN
= 12V, V
OUT
= 5V.
PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
Start-Up Voltage
l
2.25 2.42 V
Input Voltage Range V
CC
> 2.42V (Back-Driven)
l
1.92 15 V
V
IN
UVLO Threshold (Rising) V
CC
> 2.42V (Back-Driven)
l
1.8 1.9 2.0 V
V
IN
UVLO Hysteresis
l
80 100 130 mV
Output Voltage Adjust Range
l
1.4 15.75 V
Feedback Voltage
l
1.151 1.175 1.199 V
Feedback Input Current FB = 1.25V 0.1 10 nA
Quiescent Current (V
IN
) – Shutdown RUN = 0V, Including Switch Leakage 10 100 nA
Quiescent Current (V
IN
) UVLO Either V
IN
or V
CC
Below Their UVLO Threshold, or
RUN Below the Threshold to Enable Switching
1.9 3 µA
Quiescent Current – Burst Mode Operation Measured on V
IN
, FB > 1.25V
PWM = 0V, RUN = V
IN
1.3 2.0 µA
N-Channel Switch Leakage on V
IN
and V
OUT
SW1 = 0V, V
IN
= 15V
SW2 = 0V, V
OUT
= 15V
RUN = 0V
10 50 nA
N-Channel Switch On-Resistance V
CC
= 4V 0.75 Ω
Inductor Average Current Limit V
OUT
> UV Threshold (Note 4)
V
OUT
< UV Threshold (Note 4)
l
l
220
80
275
130
350
200
mA
mA
Inductor Peak Current Limit (Note 4)
l
400 500 680 mA
Maximum Boost Duty Cycle FB = 1.10V. Percentage of Period SW2 is Low in
Boost Mode (Note 7)
l
85 89 95 %
Minimum Duty Cycle FB = 1.25V. Percentage of Period SW1 is High in
Buck Mode (Note 7)
l
0 %
Switching Frequency PWM = V
CC
l
1.0 1.2 1.4 MHz
SW1 and SW2 Minimum Low Time (Note 3) 90 ns
MPPC V
oltage
l
1.12 1.175 1.22 V
MPPC Input Current MPPC = 5V 1 10 nA
RUN Threshold to Enable V
CC
l
0.5 0.9 1.15 V
RUN Threshold to Enable Switching (Rising) V
CC
> 2.4V
l
1.16 1.22 1.28 V
RUN (Switching) Threshold Hysteresis 50 80 120 mV
RUN Input Current RUN = 15V 1 10 nA
PWM Input High
l
1.6 V
PWM Input Low
l
0.5 V
PWM Input Current PWM = 5V 0.1 1 µA
Soft-Start Time 3 ms
V
CC
Voltage V
IN
> 4.85V
l
3.4 4.1 4.7 V
V
CC
Dropout Voltage (V
IN
– V
CC
) V
IN
= 3.0V, Switching
V
IN
= 2.0V (V
CC
in UVLO)
35
0
60
2
mV
mV
V
CC
UVLO Threshold (Rising)
l
2.1 2.25 2.42 V
V
CC
UVLO Hysteresis 60 mV
V
CC
Current Limit V
CC
= 0V
l
4 20 40 mA
V
CC
Back-Drive Voltage (Maximum)
l
5.5 V
V
CC
Input Current (Back-Driven) V
CC
= 5.5V (Switching) 2 4 mA
V
CC
Leakage to V
IN
if V
CC
> V
IN
V
CC
= 5.5V, V
IN
= 1.8V, Measured on V
IN
–27 µA
V
OUT
UV Threshold (Rising)
l
0.95 1.15 1.35 V