LM3478MA_15 Datasheet, PDF (3/26 Pages) Texas Instruments – High-Efficiency Low-Side N-Channel Controller for Switching Regulator

LM3478MA
www.ti.com
SNVS705B – FEBRUARY 2011 – REVISED FEBRUARY 2013
Electrical Characteristics
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
V_FB
Feedback Voltage
V_COMP = 1.4V,
2.97 ≤ V_IN ≤ 40V
1.26
V
1.2416/1.22 V(min)
8
V(max)
1.2843/1.29
2
ΔV_LINE
ΔV_LOAD
V_UVLO
Feedback Voltage Line Regulation
Output Voltage Load Regulation
Input Undervoltage Lock-out
2.97 ≤ V_IN ≤ 40V
I_EAO Source/Sink
0.001
±0.5
2.85
%/V
%/A (max)
V
2.97
V(max)
V_UV(HYS)
Input Undervoltage Lock-out Hysteresis
170
mV
130
mV (min)
210
mV (max)
F_nom
Nominal Switching Frequency
R_FA = 40KΩ
400
kHz
350
kHz(min)
440
kHz(max)
R_{DS1 (ON)}
R_{DS2 (ON)}
V_{DR (max)}
D_max
T_min (on)
Driver Switch On Resistance (top)
Driver Switch On Resistance (bottom)
Maximum Drive Voltage Swing⁽¹⁾
Maximum Duty Cycle⁽²⁾
Minimum On Time
I_DR = 0.2A, V_IN= 5V
I_DR = 0.2A
V_IN < 7.2V
V_IN ≥ 7.2V
I_SUPPLY
I_Q
V_SENSE
Supply Current (non-switching)
Quiescent Current in Shutdown Mode
Current Sense Threshold Voltage
(3)
V_FA/SD = 5V ⁽⁴⁾,
V_IN = 5V
V_IN = 5V
16
Ω
4.5
Ω
V_IN
V
7.2
100
%
325
nsec
210
nsec(min)
600
nsec(max)
2.7
mA
3.3
mA (max)
5
µA
10
µA (max)
156
mV
135/ 125 mV (min)
180/ 190 mV (max)
V_SC
Short-Circuit Current Limit Sense
V_IN = 5V
Voltage
343
mV
250
mV (min)
415
mV (max)
V_SL
Internal Compensation Ramp Voltage V_IN = 5V
92
mV
52
mV(min)
132
mV(max)
V_SL ratio
V_SL/V_SENSE
0.49
0.30
(min)
0.70
(max)
V_OVP
Output Over-voltage Protection (with
respect to feedback voltage) ⁽⁵⁾
V_COMP = 1.4V
50
mV
32/ 25
mV(min)
78/ 100
mV(max)
V_OVP(HYS)
Output Over-Voltage Protection
Hysteresis ⁽⁵⁾
V_COMP = 1.4V
60
mV
20
mV(min)
110
mV(max)
Gm
Error Amplifier Transconductance
V_COMP = 1.4V
I_EAO = 100µA (Source/Sink)
800
µmho
600/ 365 µmho (min)
1000/ 1265 µmho (max)
(1) The voltage on the drive pin, V_DR is equal to the input voltage when input voltage is less than 7.2V. V_DR is equal to 7.2V when the input
voltage is greater than or equal to 7.2V.
(2) The limits for the maximum duty cycle can not be specified since the part does not permit less than 100% maximum duty cycle
operation.
(3) For this test, the FA/SD pin is pulled to ground using a 40K resistor.
(4) For this test, the FA/SD pin is pulled to 5V using a 40K resistor.
(5) 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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