LT1777C View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LT1777C' PDF : 24 Pages View PDF
LT1777
ELECTRICAL CHARACTERISTICS
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are at TJ = 25°C.
VIN = 24V, VSW Open, VCC = 5V, VC = 1.4V unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX
Output Switch
RON
Output Switch On Voltage
ILIM
Switch Current Limit
Output dl/dt Sense Voltage
ISW = 0.5A
(Note 3)
1.0
1.5
q 0.55 0.70
1.0
1.3
q 0.6
2.0
Current Amplifier
Control Pin Threshold
Duty Cycle = 0%
0.9
1.1
1.25
Control Voltage to Switch Transconductance
2
Timing
f
Switching Frequency
90
q
85
100 110
115
Maximum Switch Duty Cycle
q
85
90
Sync Function
Minimum Sync Amplitude
q
1.5
2.2
Synchronization Range
q 130
250
SYNC Pin Input R
40
SHDN Pin Function
VSHDN
Shutdown Mode Threshold
0.5
q 0.2
0.8
Upper Lockout Threshold
Switching Action On
1.260
Lower Lockout Threshold
Switching Action Off
1.245
ISHDN
Shutdown Pin Current
VSHDN = 0V
VSHDN = 1.25V
12
20
2.5
10
UNITS
V
A
V
V
V
A/V
kHz
kHz
%
V
kHz
kΩ
V
V
V
V
µA
µA
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: Control circuitry powered from VCC.
Note 3: Switch current limit is DC trimmed and tested in production.
Inductor dI/dt rate will cause a somewhat higher current limit in actual
application.
Note 4: During normal operation the VSW pin may fly as much as 3V
below ground. However, the LT1777 may not be used in an inverting
DC/DC configuration.
3
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