LM3551 Datasheet, PDF (4/15 Pages) National Semiconductor (TI) – 1A White LED Driver with Flash Timeout Protection

Electrical Characteristics(Notes 2, 9) (Continued)
Limits in standard typeface are for T_J = +25˚ C. Limits in boldface type apply over the full operating junction temperature range
(-40˚C ≤ T_J ≤ +110˚C). Unless otherwise noted, specifications apply to the LM3551 and LM3552 Typical Application Circuit (pg.
1) with: V_IN = 3.6V, V(SD) = 0V for LM3551 and V(EN) = V_IN for LM3552, I_LOAD = 0A (Note 10)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
Th_T/F
T/F Pin Threshold
Output High
1.2
Output Low
V
0.3
UVP
Under Voltage Protection
Thresholds
On Threshold
Off Threshold
2.25
2.48
2.70
V
2.43
2.58
2.77
OVP
Over Voltage Protection
Thresholds
On Threshold
Off Threshold
11
12.4
14
V
9.2
10.6
12
V_FTO
I_FTO
V_SS
I_SS
Flash Timeout trip-point
Flash Timeout Current
Soft-Start Voltage
Soft-Start Current
0.99
1.16
1.32
V
1.12
1.4
1.68
µA
1.18
1.25
1.32
V
10
11.5
13
µA
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under which operation of
the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the
Electrical Characteristics tables.
Note 2: All voltages are with respect to the potential at the GND pin.
Note 3: Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at T_J=140^oC (typ.) and disengages at
T_J=120^oC (typ.).
Note 4: For detailed soldering specifications and information, please refer to National Semiconductor Application Note: AN-1187 for Recommended Soldering
Profiles.
Note 5: The human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin. (MIL-STD-883 3015.7)
Note 6: Maximum recommended SW pin voltage when the OVP pin is grounded.
Note 7: In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may have to be
derated. Maximum ambient temperature (T_A-MAX) is dependent on the maximum operating junction temperature (T_J-MAX-OP = 110^oC), the maximum power
dissipation of the device in the application (P_D-MAX), and the junction-to-ambient thermal resistance of the part/package in the application (θ_JA), as given by the
following equation: T_A-MAX = T_J-MAX-OP – (θ_JA x P_D-MAX).
Note 8: Junction-to-ambient thermal resistance is highly application and board-layout dependent. In applications where high maximum power dissipation exists,
special care must be paid to thermal dissipation issues in board design.
Note 9: Min and Max limits are guaranteed by design, test, or statistical analysis. Typical (Typ) numbers are not guaranteed, but do represent the most likely norm.
Unless otherwise specified, conditions for Typ specifications are: V_IN = 3.6V and T_A = 25^oC.
Note 10: C_IN and C_OUT,: Low-ESR Surface-Mount Ceramic Capacitors (MLCCs) used in setting electrical characteristics
Note 11: Duty cycle affects current limit due to ramp generator.
Note 12: Current limit at 0% duty cycle. See TYPICAL PERFORMANCE section for Switch Current Limit vs. V_IN
Note 13: Bias current flows into FB pin.
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