Datasheet LT1777 (Analog Devices) - 3

LT1777
ELECTRICAL CHARACTERISTICS The
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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 UNITS Output Switch
RON Output Switch On Voltage ISW = 0.5A 1.0 1.5 V ILIM Switch Current Limit (Note 3) ● 0.55 0.70 1.0 A Output dl/dt Sense Voltage 1.3 V ● 0.6 2.0 V
Current Amplifier
Control Pin Threshold Duty Cycle = 0% 0.9 1.1 1.25 V Control Voltage to Switch Transconductance 2 A/V
Timing
f Switching Frequency 90 100 110 kHz ● 85 115 kHz Maximum Switch Duty Cycle ● 85 90 %
Sync Function
Minimum Sync Amplitude ● 1.5 2.2 V Synchronization Range ● 130 250 kHz SYNC Pin Input R 40 kΩ
SHDN Pin Function
VSHDN Shutdown Mode Threshold 0.5 V ● 0.2 0.8 V Upper Lockout Threshold Switching Action On 1.260 V Lower Lockout Threshold Switching Action Off 1.245 V ISHDN Shutdown Pin Current VSHDN = 0V 12 20 µA VSHDN = 1.25V 2.5 10 µA
Note 1:
Absolute Maximum Ratings are those values beyond which the life
Note 4:
During normal operation the VSW pin may fly as much as 3V of a device may be impaired. below ground. However, the LT1777 may not be used in an inverting
Note 2:
Control circuitry powered from V DC/DC configuration. CC.
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. 3