LT1374C Linear Technology, LT1374C Datasheet - Page 3

• Manufacturer Part Number: LT1374C
• Description: 4.5A/ 500kHz Step-Down Switching Regulator
• Manufacturer: Linear Technology

ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: Gain is measured with a V
switching threshold level to 200mV below the upper clamp level.
Note 3: Minimum input voltage is not measured directly, but is guaranteed
by other tests. It is defined as the voltage where internal bias lines are still
regulated so that the reference voltage and oscillator frequency remain
constant. Actual minimum input voltage to maintain a regulated output will
depend on output voltage and load current. See Applications Information.
Note 4: This is the minimum voltage across the boost capacitor needed to
guarantee full saturation of the internal power switch.
Note 5: Boost current is the current flowing into the boost pin with the pin
held 5V above input voltage. It flows only during switch on time.
ture range, otherwise specifications are at T
PARAMETER
Feedback Input Bias Current
Error Amplifier Voltage Gain
Error Amplifier Transconductance
V
Error Amplifier Source Current
Error Amplifier Sink Current
V
V
Switch Current Limit
Slope Compensation (Note 9)
Switch On Resistance (Note 7)
Maximum Switch Duty Cycle
Switch Frequency
Switch Frequency Line Regulation
Frequency Shifting Threshold on FB Pin
Minimum Input Voltage (Note 3)
Minimum Boost Voltage (Note 4)
Boost Current (Note 5)
V
BIAS Supply Current (Note 6)
Shutdown Supply Current
Lockout Threshold
Shutdown Thresholds
Synchronization Threshold
Synchronizing Range
SYNC Pin Input Resistance
C
C
C
IN
Pin to Switch Current Transconductance
Pin Switching Threshold
Pin High Clamp
Supply Current (Note 6)
C
swing equal to 200mV above the
CONDITIONS
(Notes 2, 8)
V
V
Duty Cycle = 0
V
DC = 80%
I
V
V
5V V
I
I
I
V
V
V
V
V
V
Device Starting Up
SW
SW
SW
SW
FB
FB
C
FB
C
BIAS
BIAS
SHDN
SHDN
C
C
I (V
f = 10kHz
Open, V
Set to Give 50% Duty Cycle
Open
Open Device Shutting Down
J
= 2.1V or V
= 2.7V or V
= 2.1V or V
= 4.5A
= 1A
= 4.5A
C
= 25 C. V
= 5V
= 5V
) = 10 A (Note 8)
4.5A
IN
= 0V, V
= 0V, V
FB
25V, (5V V
= 2.1V or V
IN
IN
SENSE
SENSE
SENSE
IN
25V, V
32V, V
= 15V, V
The
= 4.4V
= 5.6V
= 4.4V
IN
SENSE
SW
SW
denotes specifications which apply over the full operating tempera-
32V for LT1374HV)
= 0V, V
= 0V, V
C
= 1.5V, Boost = V
= 4.4V, DC 50%
Note 6: V
at 5V and switching is disabled. If the BIAS pin is unavailable or open
circuit, the sum of V
pin.
Note 7: Switch on resistance is calculated by dividing V
by the forced current (4.5A). See Typical Performance Characteristics for
the graph of switch voltage at other currents.
Note 8: Transconductance and voltage gain refer to the internal amplifier
exclusive of the voltage divider. To calculate gain and transconductance,
refer to the SENSE pin on the fixed voltage parts. Divide values shown by
the ratio V
Note 9: Slope compensation is the current subtracted from the switch
current limit at 80% duty cycle. See Maximum Output Load Current in the
Applications Information section for further details.
C
C
Open
Open
IN
OUT
supply current is the current drawn when the BIAS pin is held
/2.42.
IN
IN
+ 5V, switch open, unless otherwise noted.
and BIAS supply currents will be drawn by the V
1500
1000
0.13
0.25
MIN
200
140
140
460
440
580
4.5
0.8
2.3
90
86
2000
0.07
2.38
0.37
0.45
TYP
400
225
225
500
0.5
5.3
0.9
2.1
0.8
1.0
5.0
2.3
0.9
3.2
1.5
93
93
20
90
20
30
40
6
0
IN
MAX
2700
3100
1000
0.13
0.15
2.46
0.60
320
320
540
560
140
100
8.5
0.1
1.3
5.5
3.0
1.4
4.0
0.7
2.2
35
50
75
75
to V
2
LT1374
SW
voltage
UNITS
3
Mho
Mho
%/ V
IN
A/ V
kHz
kHz
kHz
mA
mA
mA
mA
k
%
%
A
A
A
V
V
A
A
V
V
V
A
A
A
A
V
V
V
V