LT1766 Linear Technology, LT1766 Datasheet - Page 3

• Manufacturer Part Number: LT1766
• Description: 5.5V to 60V 1.5A/ 200kHz Step-Down Switching Regulator
• Manufacturer: Linear Technology

ELECTRICAL CHARACTERISTICS
The
V
PARAMETER
Switch Current Limit
Switch On Resistance
Maximum Switch Duty Cycle
Switch Frequency
f
f
Minimum Input Voltage
Minimum Boost Voltage
Boost Current (Note 5)
Input Supply Current (I
Bias Supply Current (I
Shutdown Supply Current
Lockout Threshold
Shutdown Thresholds
Minimum SYNC Amplitude
SYNC Frequency Range
SYNC Input Resistance
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
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 remain constant.
Actual minimum input voltage to maintain a regulated output will depend
upon 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 quiescent current drawn by the input
pin when the BIAS pin is held at 5V with switching disabled. Bias supply
current is the current drawn by the BIAS pin when the BIAS pin is held at
5V. Total input referred supply current is calculated by summing input
supply current (I
With V
SW
SW
IN
I
Line Regulation
Frequency Shifting Threshold
= 15V, V
TOTAL
IN
denotes specifications which apply over the full operating temperature range, otherwise specifications are at T
= 15V, V
= I
VIN
C
= 1.5V, SHDN = 1V, BOOST open circuit, SW open circuit, unless otherwise noted.
VIN
+ (I
OUT
) with a fraction of bias supply current (I
BIAS
= 5V, I
BIAS
VIN
)(V
)
)
OUT
VIN
/V
= 1.4mA, I
IN
C
)
swing equal to 200mV above the low
BIAS
= 2.9mA, I
CONDITIONS
V
I
FB = 1V or V
V
5.5V V
Df = 10kHz
(Note 3)
(Note 4) I
Boost = V
Boost = V
(Note 6) V
(Note 6) V
SHDN = 0V, V
V
V
V
SW
C
C
C
C
C
Open, Boost = V
Set to Give DC = 50%
Open
Open, Shutting Down
Open, Starting Up
TOTAL
= 1.5A, Boost = V
BIAS
IN
= 2.4mA.
SW
IN
IN
):
BIAS
BIAS
+ 5V, I
+ 5V, I
SENSE
60V
IN
= 5V
= 5V
1.5A
60V, SW = 0V, V
= 4.1V
SW
SW
IN
IN
+ 5V, FB = 1V or V
= 0.5A
= 1.5A
+ 5V (Note 7)
Note 7: Switch on resistance is calculated by dividing V
the forced current (1.5A). See Typical Performance Characteristics for the
graph of switch voltage at other currents.
Note 8: The LT1766EGN, LT1766EGN-5, LT1766EFE and LT1766EFE-5 are
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 LT1766IGN,
LT1766IGN-5, LT1766IFE and LT1766IFE-5 are guaranteed over the full
–40 C to 125 C operating junction temperature range.
Note 9: 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 fixed voltage parts. Divide the values shown by
the ratio V
Note 10: 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.
C
OUT
Open
/1.219.
SENSE
= 4.1V
LT1766/LT1766-5
0.15
0.25
MIN
184
172
228
1.5
2.3
93
90
0.05
2.42
0.37
0.45
TYP
200
200
0.2
0.8
4.6
1.8
1.4
2.9
1.5
96
12
45
25
20
2
J
IN
MAX
= 25 C.
0.15
2.53
216
228
200
700
0.4
5.5
2.2
4.2
0.6
0.6
2.2
0.3
25
70
75
to SW voltage by
3
3
UNITS
1766fa
3
%/V
kHz
kHz
kHz
mA
mA
mA
mA
k
%
%
A
V
V
V
A
A
V
V
V
V