3
LTC3251/
LTC3251-1.2/LTC3251-1.5
32511215fb
V
IN
(V)
2.7
10
9
8
7
6
5
4
3
2
1
0
4.2 5.2
3251 G17
3.2 3.7
4.7
I
CC
(mA)
–40°C
25°C
85°C
V
IN
(V)
2.7
50
45
40
85°C
25°C
–40°C
35
30
25
20
4.2 5.2
3251 G02
3.2 3.7
4.7
I
IN
(µA)
V
IN
(V)
2.7
7
6
5
4
3
2
1
0
4.2 5.2
3251 G01
3.2 3.7
4.7
I
IN
(mA)
–40°C
25°C
85°C
TYPICAL PERFOR A CE CHARACTERISTICS
UW
No Load Supply Current vs Supply
Voltage (Continuous Mode Spread
Spectrum Enabled)
No Load Supply Current vs Supply
Voltage (Burst Mode Operation)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Line Regulation (LTC3251) I
OUT
= 500mA, 2.7V ≤ V
IN
≤ 5.5V 0.2 %/V
Spread Spectrum Frequency Range f
MIN
Switching Frequency ● 0.7 1.0 MHz
f
MAX
Switching Frequency ● 1.6 2 MHZ
Spread Spectrum Disabled Frequency MODE = V
IN
● 1.3 1.6 2 MHz
MD0, MD1 Input High Voltage 2.7V ≤ V
IN
≤ 5.5V ● 0.8 1.2 V
MD0, MD1 Input Low Voltage 2.7V ≤ V
IN
≤ 5.5V ● 0.4 0.8 V
MD0, MD1 Input High Current MD0 = V
IN
, MD1 = V
IN
● –1 1 µA
MD0, MD1 Input Low Current MD0 = 0V, MD1 = 0V ● –1 1 µA
FB Input Current (LTC3251) V
FB
= 0.85V ● –50 50 nA
MODE Input High Voltage (LTC3251-1.2/LTC3251-1.5) 2.7V ≤ V
IN
≤ 5.5V ● 50 70 %/V
IN
MODE Input Low Voltage (LTC3251-1.2/LTC3251-1.5) 2.7V ≤ V
IN
≤ 5.5V ● 30 50 %/V
IN
MODE Input High Current (LTC3251-1.2/LTC3251-1.5) MODE = V
IN
● –1 1 µA
MODE Input Low Current (LTC3251-1.2/LTC3251-1.5) MODE = 0V ● –1 1 µA
Turn-On Time (Burst or Continuous Mode Operation) R
OL
= 3Ω, (Note 5) 1 ms
Open-Loop Output Impedance (LTC3251) V
IN
= 3V, I
OUT
= 200mA (Note 6) ● 0.45 0.7 Ω
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: Based on long term current density limitations.
Note 3: The LTC3251E is guaranteed to meet specified performance from
0°C to 70°C. Specifications over the – 40°C to 85°C operating temperature
range are assured by design, characterization and correlation with
statistical process controls.
Note 4: Minimum operating voltage required for regulation is:
V
IN
≥ 2 • (V
OUT
+ R
OL
• I
OUT
)
Note 5: V
MODE
= 0V or V
MODE
= V
IN
for LTC3251-1.2/LTC3251-1.5.
Note 6: Output not in regulation; R
OL
= (V
IN
/2 – V
OUT
)/I
OUT
.
(V
FB
= 0.76V). Burst or continuous mode operation.
Note 7: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V, C1 = C2 = 1µF, C
IN
= 1µF, C
OUT
= 10µF,
V
MODE
= 0V for LTC3251-1.2V or LTC3251-1.5, V
OUT
= 1.5V for LTC3251, all capacitors ceramic, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
No Load Supply Current vs Supply
Voltage (Continuous Mode,
Spread Spectrum Disabled)
