LM3557 Datasheet, PDF (3/11 Pages) National Semiconductor (TI) – Step-Up Converter for White LED Applications

Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
V_IN Pin
En Pin
Fb Pin
Sw2 Pin
Ovp Pin
Sw1 Pin
Continuous Power Dissipation
Maximum Junction Temperature
(T_J-MAX)
Storage Temperature Range
−0.3V to +8V
−0.3V to +8V
−0.3V to +8V
−0.3V to +8V
−0.3V to +30V
−0.3V to +40V
Internally Limited
+150˚C
−65˚C to +150˚C
ESD Rating (Note 2)
Human Body Model
Machine Model
2 kV
150V
Operating Conditions (Notes 1, 6)
Junction Temperature (T_J) Range
Ambient Temperature (T_A) Range
Supply Voltage, V_IN Pin
En Pin
−40˚C to +125˚C
−40˚C to +85˚C
2.7V to 7.5V
0V to V_IN +0.4V
Thermal Properties (Notes 4, 7)
Junction-to-Ambient Thermal
55˚C/W
Resistance (θ_JA), Leadless Leadframe Package
Electrical Characteristics (Notes 6, 8) Limits in standard typeface are for T_J = 25˚C. Limits in bold type-
face apply over the full operating junction temperature range (−40˚C ≤ T_J ≤ +125˚C). Unless otherwise specified: V_IN = 3.6V.
Symbol
V_IN
I_Q
En
I_CL
R_DS(ON)
TC
(R_DS(ON))
OVP
UVP
I_OVP
I_EN
F_S
V_Fb-Sw2
I_Fb
D_MAX
I_LSw1
I_LSw2
I_LOVP
R_Sw2
TC(R_Sw2)
Parameter
Input Voltage
Quiescent Current
Device Enable Threshold
Power Switch Current Limit
(Note 10)
Power Switch ON Resistance
R_DS(ON) Temperature
Coefficient
Over-Voltage Protection (Note
5)
Under-Voltage Protection (Note
5)
Over-Voltage Protection Pin
Bias Current (Note 3)
Enable Pin Bias Current (Note
3)
Switching Frequency
Feedback Pin Voltage (Note 9)
Feedback Pin Bias Current
(Note 3)
Maximum Duty Cycle
Sw1 Pin Leakage Current (Note
3)
Sw2 Pin Leakage Current (Note
3)
Ovp Pin Leakage Current (Note
3)
Sw2 Pin Switch Resistance
R_Sw2 Temperature Coefficient
Conditions
V_EN = 0V (Shutdown)
V_EN = 1.8V; V_OVP = 27V
(Non-Switching)
Device On
Device Off
V_IN = 3V
I_Sw1 = 175 mA
On Threshold
Off Threshold
On Threshold
Off Threshold
V_EN = 1.8V
V_IN = 3V
V_IN = 3V
V_Sw1 = 3.6V, Not Switching
V_Sw2 = 3.6V, Not Switching
V_Ovp = 3.6V, Not Switching
I_Sw2 = 50 mA
Min
2.7
0.9
0.4
0.55
22
21.5
0.9
0.459
85
Typ
0.01
0.55
0.8
0.8
800
0.5
26
25.5
2.2
2.3
4
0.8
1.25
0.51
0.03
90
0.002
0.001
2
8
0.5
Max
7.5
2
0.8
0.3
1.1
1.02
1000
28.5
28
10
3
1.6
0.561
2
2
1
10
Units
V
µA
mA
V
A
mΩ
%/C
V
V
µA
µA
MHz
V
µA
%
µA
µA
nA
Ω
%/C
Note 1: Absolute maximum ratings indicate limits beyond which damage to the device may occur. Electrical characteristic specifications do not apply when
operating the device outside of its rated operating conditions.
Note 2: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200 pF capacitor discharged
directly into each pin.
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