Datasheet LT1738 (Analog Devices) - 3

LT1738
ELECTRICAL CHARACTERISTICS The
●
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25
°
C. VIN = 12V, VC = 0.9V, VFB = VREF, RVSL, RCSL = 16.9k, RT = 16.9k and other pins open unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Oscillator and Sync
fMAX Max Switch Frequency 250 kHz fSYNC Synchronization Frequency Range Oscillator Frequency = 250kHz 290 kHz VSYNC SYNC Pin Input Threshold ● 0.7 1.4 2 RSYNC SYNC Pin Input Resistance 40 kΩ
Gate Drive
DCMAX Maximum Switch Duty Cycle RVSL = RCSL = 3.9k, ● 90 93.5 % Osc Frequency = 25kHz VGON Gate On Voltage VIN = 12, GCL = 12 10 10.4 10.7 V VIN = 12, GCL = 8 7.6 7.9 8.1 V VGOFF Gate Off Voltage VIN = 12V 0.2 0.35 V IGSO Max Gate Source Current VIN = 12V 0.3 A IGSK Max Gate Sink Current VIN = 12V 0.3 A VINUVLO Gate Drive Undervoltage Lockout (Note 5) VGCL = 6.5V 7.3 7.5 V
Current Sense
tIBL Switch Current Limit Blanking Time 100 ns VSENSE Sense Voltage Shutdown Voltage VC Pulled Low ● 86 103 120 mV VSENSEF Sense Voltage Fault Threshold 220 300 mV
Slew Control for the Following Slew Tests See Test Circuit in Figure 1b
VSLEWR Output Voltage Slew Rising Edge RVSL = RCSL = 17k 26 V/µs VSLEWF Output Voltage Slew Falling Edge RVSL = RCSL = 17k 19 V/µs VISLEWR Output Current Slew Rising Edge (CS pin V) RVSL = RCSL = 17k 2.1 V/µs VISLEWF Output Current Slew Falling Edge (CS pin V) RVSL = RCSL = 17k 2.1 V/µs
Supply and Protection
VINMIN Minimum Input Voltage (Note 4) VGCL = VIN ● 2.55 3.6 V IVIN Supply Current (Note 3) RVSL = RCSL = 17k VIN = 12 ● 12 40 mA RVSL = RCSL = 17k VIN = 20 35 55 mA VSHDN Shutdown Turn-On Threshold ● 1.31 1.39 1.48 V ∆VSHDN Shutdown Turn-On Voltage Hysteresis ● 50 110 180 mV ISHDN Shutdown Input Current Hysteresis ● 10 24 35 µA V5 5V Reference Voltage 6.5V ≤ VIN ≤ 20V, IV5 = 5mA 4.85 5 5.20 V 6.5V ≤ VIN ≤ 20V, IV5 = – 5mA 4.80 5 5.15 V IV5SC 5V Reference Short-Circuit Current VIN = 6.5V Source 10 mA VIN = 6.5V Sink –10 mA
Note 1:
Absolute Maximum Ratings are those values beyond which the design, characterization and correlation with statistical process life of a device may be impaired. controls.The LT1738I is guaranteed and tested to meet performance
Note 2:
Supply current specification includes loads on each gate as in specifications from – 40°C to 125°C. Figure 1a. Actual supply currents vary with operating frequency, operating
Note 4:
Output gate drive is enabled at this voltage. The GCL voltage will voltages, V5 load, slew rates and type of external FET. also determine driver activity.
Note 3:
The LT1738E is guaranteed to meet performance specifications
Note 5:
Gate drive is ensured to be on when VIN is greater than max value. from 0°C to 70°C. Specifications from –40°C to 125°C are assured by 1738fa 3