Datasheet

LM3478
LM3478-Q1
SNVS085V –JULY 2000–REVISED FEBRUARY 2013 www.ti.com
Electrical Characteristics (continued)
Specifications in Standard type face are for T
J
= 25°C, and in bold type face apply over the full Operating Temperature
Range. Unless otherwise specified, V
IN
= 12V, R
FA
= 40kΩ
Symbol Parameter Conditions Typical Limit Unit
Gm Error Amplifier V
COMP
= 1.4V 800 µmho
Transconductance I
EAO
= 100µA (Source/Sink) 600/ 365 µmho (min)
1000/ 1265 µmho (max)
A
VOL
Error Amplifier Voltage Gain V
COMP
= 1.4V 38 V/V
I
EAO
= 100µA (Source/Sink) 26 V/V (min)
44 V/V (max)
I
EAO
Error Amplifier Output Current Source, V
COMP
= 1.4V, V
FB
= 0V 110 µA
(Source/ Sink) 80/ 50 µA (min)
140/ 180 µA (max)
Sink, V
COMP
= 1.4V, V
FB
= 1.4V −140 µA
−100/ −85 µA (min)
−180/ −185 µA (max)
V
EAO
Error Amplifier Output Voltage Upper Limit 2.2 V
Swing V
FB
= 0V 1.8 V(min)
COMP Pin = Floating 2.4 V(max)
Lower Limit 0.56 V
V
FB
= 1.4V 0.2 V(min)
1.0 V(max)
T
SS
Internal Soft-Start Delay V
FB
= 1.2V, V
COMP
= Floating 4 msec
T
r
Drive Pin Rise Time Cgs = 3000pf, V
DR
= 0 to 3V 25 ns
T
f
Drive Pin Fall Time Cgs = 3000pf, V
DR
= 0 to 3V 25 ns
V
SD
Shutdown threshold
(6)
Output = High 1.27 1.4 V
V (max)
Output = Low 0.65 0.3 V
V (min)
I
SD
Shutdown Pin Current V
SD
= 5V −1 µA
V
SD
= 0V +1
I
FB
Feedback Pin Current 15 nA
T
SD
Thermal Shutdown 165 °C
T
sh
Thermal Shutdown Hysteresis 10 °C
θ
JA
Thermal Resistance VSSOP Package 200 °C/W
SOIC Package 151
(6) The FA/SD pin should be pulled to V
IN
through a resistor to turn the regulator off. The voltage on the FA/SD pin must be above the
maximum limit for Output = High to keep the regulator off and must be below the limit for Output = Low to keep the regulator on.
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