Datasheet

LM3477
SNVS141K –OCTOBER 2000–REVISED MARCH 2013 www.ti.com
Electrical Characteristics
(1)
(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.
Symbol Parameter Conditions Typical Limit Units
I
SUPPLY
Supply Current (switching)
(2)
2.0 mA
3.0 mA (max)
I
Q
Quiescent Current in Shutdown Mode
(3)
, V
IN
= 5V 5 µA
8 µA (max)
V
CL(O)
Current Limit Voltage at 0% Duty Cycle LM3477 155 mV
130/125 mV (min)
185/190 mV (max)
LM3477A 165 mV
140/135 mV (min)
195/200 mV (max)
V
CL(100)
Current Limit Voltage at 100% Duty LM3477 74 mV
Cycle 50/43 mV (min)
98/98 mV (max)
LM3477A 65 mV
41/25 mV (min)
89/98 mV (max)
V
SC
Short-Circuit Current Limit Sense V
IN
= 5V, LM3477 350 mV
Voltage 270 mV (min)
420 mV (max)
V
IN
= 5V, LM3477A 310 mV
260 mV (min)
380 mV (max)
V
SL
Internal Compensation Ramp Voltage V
IN
= 5V, LM3477 83 mV
Height
V
IN
= 5V, LM3477A 103
V
OVP
Output Over-voltage Protection (with V
COMP
= 1.4V 50 mV
32/25
respect to feedback voltage)
(4)
mV(min)
78/85
mV(max)
V
OVP(HYS)
Output Over-Voltage Protection V
COMP
= 1.4V 60 mV
Hysteresis
(4)
20 mV(min)
110 mV(max)
Gm Error Amplifier Transconductance V
COMP
= 1.4V 750 µmho
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) 30 V/V (min)
42 V/V (max)
I
EAO
Error Amplifier Output Current (Source/ Source, V
COMP
= 1.4V, V
FB
= 100 µA
Sink) 0V 75/50 µA (min)
130/160 µA (max)
Sink, V
COMP
= 1.4V, V
FB
= 1.4V −140 µA
−110/−95 µA (min)
−170/−180 µA (max)
V
EAO
Error Amplifier Output Voltage Swing Upper Limit 2.2 V
V
FB
= 0V 2.0 V(min)
COMP Pin = Floating 2.35 V(max)
Lower Limit 0.75 V
V
FB
= 1.4V 0.5 V(min)
0.95 V(max)
T
SS
Internal Soft-Start Delay V
FB
= 1.2V, V
COMP
= Floating 5 msec
T
r
Drive Pin Rise Time C
GS
= 3000pF, V
DR
= 0 to 3V 25 ns
T
f
Drive Pin Fall Time C
GS
= 3000pF, V
DR
= 0 to 3V 25 ns
(2) For this test, the COMP/SD pin must be left floating.
(3) For this test, the COMP/SD pin must be pulled low.
(4) The over-voltage protection is specified with respect to the feedback voltage. This is because the over-voltage protection tracks the
feedback voltage. The overvoltage protection threshold is given by adding the feedback voltage, V
FB
to the over-voltage protection
specification.
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