Datasheet LT1676 (Analog Devices) - 3

LT1676
ELECTRICAL CHARACTERISTICS The
●
denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25
°
C. VIN = 48V, VSW open, VCC = 5V, VC = 1.4V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Timing
f Switching Frequency 90 100 110 kHz ● 85 115 kHz Maximum Switch Duty Cycle ● 85 90 % tON(MIN) Minimum Switch On Time High dV/dt Mode, RL = 50Ω (Note 4) 300 ns
Boost Operation
VC Pin Boost Threshold 1.35 V dV/dt Below Threshold 0.2 V/ns dV/dt Above Threshold 1.6 V/ns
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 3:
Switch current limit is DC trimmed and tested in production. of a device may be impaired. Inductor dl/dt rate will cause a somewhat higher current limit in actual
Note 2:
Control circuitry powered from V application. CC.
Note 4:
Minimum switch on time is production tested with a 50Ω resistive load to ground.
W U TYPICAL PERFORMANCE CHARACTERISTICS Minimum Input Voltage vs Switch-On Voltage vs Switch Current Limit vs Temperature Switch Current Duty Cycle
7.4 1.50 1000 TA = 25°C 7.2 1.25 800 25°C 7.0 – 55°C 1.00 600 6.8 0.75 6.6 125°C 400 0.50 INPUT VOLTAGE (V) 6.4 SWITCH VOLTAGE (V) SWITCH CURRENT LIMIT (mA) 200 6.2 0.25 6.0 0 0 –50 –25 0 25 50 75 100 125 0 100 200 300 400 500 600 700 0 10 20 30 40 50 60 70 80 90 100 TEMPERATURE (°C) SWITCH CURRENT (mA) DUTY CYCLE (%) LT1676 G01 1676 G02 1676 G03 3