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