LM3429_14 Datasheet, PDF (6/50 Pages) Texas Instruments – LM3429Q1 N-Channel Controller for Constant Current LED Drivers

LM3429
SNVS616F – APRIL 2009 – REVISED JANUARY 2010
www.ti.com
Electrical Characteristics ⁽¹⁾ (continued)
Specifications in standard type face are for T_J = 25°C and those with boldface type apply over the full Operating
Temperature Range ( T_J = −40°C to +125°C). Minimum and Maximum limits are guaranteed through test, design, or
statistical correlation. Typical values represent the most likely parametric norm at T_J = +25°C, and are provided for reference
purposes only. Unless otherwise stated the following condition applies: V_IN = +14V.
Symbol
Parameter
Conditions
Min
Typ
(2)
(3)
Max
(2)
Units
Transconductance
Bandwidth
I_CSH = 100 µA
(4)
GATE DRIVER (GATE)
R_SRC(GATE)
GATE Sourcing Resistance GATE = High
R_SNK(GATE)
GATE Sinking Resistance GATE = Low
UNDER-VOLTAGE LOCKOUT and DIM INPUT (nDIM)
V_TH-nDIM
nDIM / UVLO Threshold
I_HYS-nDIM
nDIM Hysteresis Current
THERMAL SHUTDOWN
T_SD
Thermal Shutdown
(4)
Threshold
T_HYS
Thermal Shutdown
(4)
Hysteresis
THERMAL RESISTANCE
θ_JA
Junction to Ambient
14L TSSOP EP
(5)
250
1.180
10
500
2.0
1.3
1.240
20
165
25
40
kHz
6.0
Ω
4.5
1.280
V
30
µA
°C
°C/W
θ_JC
Junction to Exposed Pad 14L TSSOP EP
(DAP)
5.5
°C/W
(5) Junction-to-ambient thermal resistance is highly board-layout dependent. The numbers listed in the table are given for a reference layout
wherein the 14L TSSOP EP package has its DAP pad populated with 9 vias. In applications where high maximum power dissipation
exists, namely driving a large MosFET at high switching frequency from a high input voltage, special care must be paid to thermal
dissipation issues during board design. In high-power dissipation applications, 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 = 125°C), the
maximum power dissipation of the device in the application (P_D-MAX), and the junction-to ambient thermal resistance of the package in
the application (θ_JA), as given by the following equation: T_A-MAX = T_J-MAX-OP – (θ_JA × P_D-MAX). In most applications there is little need for
the full power dissipation capability of this advanced package. Under these circumstances, no vias would be required and the thermal
resistances would be 104 °C/W for the 14L TSSOP EP. It is possible to conservatively interpolate between the full via count thermal
resistance and the no via count thermal resistance with a straight line to get a thermal resistance for any number of vias in between
these two limits.
6
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