LTC3251_15 Datasheet, PDF (3/16 Pages) Linear Technology – 500mA High Efficiency, Low Noise, Inductorless Step-Down DC/DC Converter

LTC3251/
LTC3251-1.2/LTC3251-1.5
ELECTRICAL CHARACTERISTICS _{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.
PARAMETER
CONDITIONS
MIN
TYP MAX
UNITS
Line Regulation (LTC3251)
Spread Spectrum Frequency Range
Spread Spectrum Disabled Frequency
MD0, MD1 Input High Voltage
MD0, MD1 Input Low Voltage
MD0, MD1 Input High Current
MD0, MD1 Input Low Current
I_OUT = 500mA, 2.7V ≤ V_IN ≤ 5.5V
f_MIN Switching Frequency
f_MAX Switching Frequency
MODE = V_IN
2.7V ≤ V_IN ≤ 5.5V
2.7V ≤ V_IN ≤ 5.5V
MD0 = V_IN, MD1 = V_IN
MD0 = 0V, MD1 = 0V
0.2
%/V
●
0.7
1.0
MHz
●
1.6
2
MHZ
●
1.3
1.6
2
MHz
●
0.8
1.2
V
●
0.4
0.8
V
●
–1
1
µA
●
–1
1
µA
FB Input Current (LTC3251)
MODE Input High Voltage (LTC3251-1.2/LTC3251-1.5)
MODE Input Low Voltage (LTC3251-1.2/LTC3251-1.5)
MODE Input High Current (LTC3251-1.2/LTC3251-1.5)
MODE Input Low Current (LTC3251-1.2/LTC3251-1.5)
V_FB = 0.85V
2.7V ≤ V_IN ≤ 5.5V
2.7V ≤ V_IN ≤ 5.5V
MODE = V_IN
MODE = 0V
●
–50
50
nA
●
50
70
%/V_IN
●
30
50
%/V_IN
●
–1
1
µA
●
–1
1
µA
Turn-On Time (Burst or Continuous Mode Operation) R_OL = 3Ω, (Note 5)
Open-Loop Output Impedance (LTC3251)
V_IN = 3V, I_OUT = 200mA (Note 6)
●
1
ms
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.
TYPICAL PERFOR A CE CHARACTERISTICS
No Load Supply Current vs Supply
Voltage (Continuous Mode Spread
Spectrum Enabled)
7
–40°C
6
25°C
85°C
5
4
3
2
1
0
2.7 3.2 3.7 4.2 4.7 5.2
V_IN (V)
3251 G01
No Load Supply Current vs Supply
Voltage (Continuous Mode,
Spread Spectrum Disabled)
10
–40°C
9
25°C
8
85°C
7
6
5
4
3
2
1
0
2.7 3.2 3.7 4.2 4.7 5.2
V_IN (V)
3251 G17
No Load Supply Current vs Supply
Voltage (Burst Mode Operation)
50
45
85°C
40
25°C
35
–40°C
30
25
20
2.7 3.2 3.7 4.2 4.7 5.2
V_IN (V)
3251 G02
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