LT1375 Linear Technology, LT1375 Datasheet - Page 4

• Manufacturer Part Number: LT1375
• Description: 1.5A/ 500kHz Step-Down Switching Regulators
• Manufacturer: Linear Technology

LT1375/LT1376
ELECTRICAL CHARACTERISTICS
temperature range, otherwise specifications are at T
unless otherwise noted.
PARAMETER
Shutdown Thresholds
Minimum Synchronizing Amplitude (LT1375 Only)
Synchronizing Range (LT1375 Only)
SYNC Pin Input Resistance
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: Gain is measured with a V
clamp 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.
Note 6: Input supply current is the bias current drawn by the input pin
when the BIAS pin is held at 5V with switching disabled. Output supply
current is the current drawn by the BIAS pin when the bias pin is held at
TYPICAL PERFORMANCE CHARACTERISTICS
4
0.001
0.01
1.0
0.1
0
Inductor Core Loss
CORE LOSS IS
INDEPENDENT OF LOAD
CURRENT UNTIL LOAD CURRENT FALLS
LOW ENOUGH FOR CIRCUIT TO GO INTO
DISCONTINUOUS MODE
V
OUT
= 5V, V
5
INDUCTANCE (µH)
IN
= 10V, I
10
OUT
TYPE 52
POWDERED IRON
Kool Mµ
PERMALLOY
µ = 125
15
= 1A
C
®
swing equal to 200mV above the low
W
20
1375/76 G01
U
25
20
12
8
4
2
1.2
0.8
0.4
0.2
0.12
0.08
0.04
0.02
CONDITIONS
V
V
V
C
C
IN
2.5
2.0
1.5
1.0
0.5
Open
Open
0
= 5V
A
Switch Peak Current Limit
0
= 25°C. T
The
20
GUARANTEED MINIMUM
LT1375HV/LT1376HV Device Shutting Down
LT1375HV/LT1376HV Device Starting Up
●
J
DUTY CYCLE (%)
= 25°C, V
denotes specifications which apply over the full operating
TYPICAL
40
5V. Total input referred supply current is calculated by summing input
supply current (I
With V
For the LT1375, quiescent current is equal to:
because the BIAS pin is internally connected to V
For LT1375 or BIAS open circuit, input supply current is the sum of input
+ output supply currents.
Note 7: Switch-on resistance is calculated by dividing V
by the forced current (1.5A). 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 sense pin on fixed voltage parts. Divide values shown by the ratio
V
OUT
I
I
60
TOT
TOT
/2.42.
IN
IN
= 15V, V
= I
= I
= 15V, V
SI
SI
80
Device Shutting Down
+ (I
+ I
1375/76 G08
Device Starting Up
SO
SI
SO
OUT
C
) with a fraction of output supply current (I
(1.15)
100
)(V
= 1.5V, boost open, switch open,
= 5V, I
OUT
2.44
2.43
2.42
2.41
2.40
/V
IN
SI
–50
Feedback Pin Voltage and Current
)(1.15)
= 0.9mA, I
–25
JUNCTION TEMPERATURE (°C)
●
●
●
●
●
0
SO
0.15
0.25
0.15
0.25
MIN
580
= 3.6mA, I
VOLTAGE
CURRENT
25
IN
.
0.37
0.45
0.37
0.45
50
TYP
1.5
40
TOT
IN
75
to V
= 2.28mA.
MAX
0.60
0.60
0.70
0.70
900
2.2
SO
100
SW
1375/76 G09
):
voltage
125
UNITS
13756fd
2.0
1.5
1.0
0.5
0
kHz
kΩ
V
V
V
V
V