Datasheet

TPS54240
SLVSAA6A –APRIL 2010–REVISED DECEMBER 2012 www.ti.com
ELECTRICAL CHARACTERISTICS (continued)
T
J
= –40°C to 150°C, VIN = 3.5 to 42V (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
ERROR AMPLIFIER
Input current 50 nA
Error amplifier transconductance (g
M
) –2 μA < I
COMP
< 2 μA, V
COMP
= 1 V 310 μMhos
–2 μA < I
COMP
< 2 μA, V
COMP
= 1 V,
Error amplifier transconductance (g
M
)
70 μMhos
during slow start
V
VSENSE
= 0.4 V
Error amplifier dc gain V
VSENSE
= 0.8 V 10,000 V/V
Error amplifier bandwidth 2700 kHz
Error amplifier source/sink V
(COMP)
= 1 V, 100 mV overdrive ±27 μA
COMP to switch current
10.5 A/V
transconductance
CURRENT LIMIT
Current limit threshold VIN = 12 V, T
J
= 25°C 3.5 6.1 A
THERMAL SHUTDOWN
Thermal shutdown 182 °C
TIMING RESISTOR AND EXTERNAL CLOCK (RT/CLK PIN)
Switching Frequency Range using
100 2500 kHz
RT mode
f
SW
Switching frequency R
T
= 200 kΩ 450 581 720 kHz
Switching Frequency Range using
300 2200 kHz
CLK mode
Minimum CLK input pulse width 40 ns
RT/CLK high threshold 1.9 2.2 V
RT/CLK low threshold 0.5 0.7 V
RT/CLK falling edge to PH rising
Measured at 500 kHz with RT resistor in series 60 ns
edge delay
PLL lock in time Measured at 500 kHz 100 μs
SLOW START AND TRACKING (SS/TR)
Charge current V
SS/TR
= 0.4 V 2 μA
SS/TR-to-VSENSE matching V
SS/TR
= 0.4 V 45 mV
SS/TR-to-reference crossover 98% nominal 1.15 V
SS/TR discharge current (overload) VSENSE = 0 V, V(SS/TR) = 0.4 V 382 μA
SS/TR discharge voltage VSENSE = 0 V 54 mV
POWER GOOD (PWRGD PIN)
VSENSE falling 92%
VSENSE rising 94%
V
VSENSE
VSENSE threshold
VSENSE rising 109%
VSENSE falling 107%
Hysteresis VSENSE falling 2%
Output high leakage VSENSE = VREF, V(PWRGD) = 5.5 V, 25°C 10 nA
On resistance I(PWRGD) = 3 mA, VSENSE < 0.79 V 50 Ω
Minimum VIN for defined output V(PWRGD) < 0.5 V, II(PWRGD) = 100 μA 0.95 1.5 V
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