Datasheet

3
LT3433
3433f
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
FB
Feedback Reference Voltage 1.224 1.231 1.238 V
● 1.215 1.245 V
∆V
FB
Feedback Reference Line Regulation 5.5V ≤ V
IN
≤ 60V ● 0.002 0.01 %/V
I
FB
V
FB
Pin Input Bias Current ● 35 100 nA
g
m
Error Amplifier Transconductance ● 200 270 330 umhos
A
V
Error Amplifier Voltage Gain 66 dB
I
SW
/V
VC
Control Voltage to Switch Transconductance 0.6 A/V
f
O
Operating Frequency V
FB
> 1V 185 200 215 kHz
● 170 230 kHz
Foldback Frequency V
FB
= 0V 50 kHz
V
BURST_EN
Burst Enable Threshold 0.8 V
I
BURST_EN
Input Bias Current V
BURST_EN
≥ 2V 35 µA
t
ON(MIN)
Minimum Switch On Time R
L
= 35Ω (Note 4) ● 250 450 ns
t
OFF(MIN)
Minimum Switch Off Time R
L
= 35Ω (Note 4) ● 500 800 ns
The ● denotes specifications that apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C.
V
IN
= 13.8V, V
FB
= 1.25V, V
OUT
= 5V, V
BURST_EN
= 0V, V
BST
– V
IN
= 5V, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: Supply current specification does not include switch drive
currents. Actual supply currents will be higher.
Note 3: “Normal Operation” supply current specification does not include
I
BIAS
currents. Powering the V
BIAS
pin externally reduces I
CC
supply
current.
Note 4: Minimum times are tested using the high side switch with a 35Ω
load to ground.
Note 5: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
Note 6: The LT3433E is guaranteed to meet performance specifications
from 0°C to 125°C junction temperature. Specifications over the –40°C to
125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LT3433I is guaranteed over the full –40°C to 125°C operating junction
temperature range.
TYPICAL PERFOR A CE CHARACTERISTICS
UW
TEMPERATURE (°C)
–50
2.2
V
BIAS
OUTPUT VOLTAGE (V)
2.4
2.6
2.8
050
3433 G01
100 125
V
BIAS
Output Voltage
vs Temperature
V
IN
Supply Current
vs V
IN
Supply Voltage
V
IN
(V)
0
I
VIN
(µA)
620
590
560
530
500
3433 G02
15 30 45 60
T
A
= 25°C
V
IN
(V)
0
0
MAXIMUM OUTPUT CURRENT (mA)
100
200
300
400
500
10
20 30 40
3433 G11
50 60
BRIDGED
BUCK
SEE TYPICAL APPLICATION
ON THE FIRST PAGE OF
THIS DATA SHEET
V
OUT
= 5V
T
A
= 25°C
Maximum Output Current
vs V
IN