Datasheet LT1956, LT1956-5 (Analog Devices) - 3

LT1956/LT1956-5
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 = 15V, VC = 1.5V, SHDN = 1V, Boost o/c, SW o/c, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS
Switch Current Limit VC Open, Boost = VIN + 5V, FB = 1V or VSENSE = 4.1V ● 1.5 2 3 A Switch On Resistance ISW = 1.5A, Boost = VIN + 5V (Note 7) 0.2 0.3 Ω ● 0.4 Ω Maximum Switch Duty Cycle FB = 1V or VSENSE = 4.1V 82 90 % ● 75 90 % Switch Frequency VC Set to Give DC = 50% 460 500 540 kHz ● 430 570 kHz fSW Line Regulation 5.5V ≤ VIN ≤ 60V ● 0.05 0.15 %/V fSW Shifting Threshold Df = 10kHz 0.8 V Minimum Input Voltage (Note 3) ● 4.6 5.5 V Minimum Boost Voltage (Note 4) ISW ≤ 1.5A ● 2 3 V Boost Current (Note 5) Boost = VIN + 5V, ISW = 0.5A ● 12 25 mA Boost = VIN + 5V, ISW = 1.5A ● 42 70 mA Input Supply Current (IVIN) (Note 6) VBIAS = 5V 1.4 2.2 mA Output Supply Current (IBIAS) (Note 6) VBIAS = 5V 2.9 4.2 mA Shutdown Supply Current SHDN = 0V, VIN ≤ 60V, SW = 0V, VC Open 25 75 µA ● 200 µA Lockout Threshold VC Open ● 2.30 2.42 2.53 V Shutdown Thresholds VC Open, Shutting Down ● 0.15 0.37 0.6 V VC Open, Starting Up ● 0.25 0.45 0.6 V Minimum SYNC Amplitude ● 1.5 2.2 V SYNC Frequency Range 580 700 kHz SYNC Input Resistance 20 kΩ
Note 1:
Absolute Maximum Ratings are those values beyond which the life
Note 7:
Switch on resistance is calculated by dividing VIN to SW voltage by of a device may be impaired. the forced current (1.5A). See Typical Performance Characteristics for the
Note 2:
Gain is measured with a V graph of switch voltage at other currents. C swing equal to 200mV above the low clamp level to 200mV below the upper clamp level.
Note 8:
The LT1956EFE/LT1956EFE-5/LT1956EGN/LT1956EGN-5 are
Note 3:
Minimum input voltage is not measured directly, but is guaranteed guaranteed to meet performance specifications from 0°C to 125°C by other tests. It is defined as the voltage where internal bias lines are still junction temperature. Specifications over the –40°C to 125°C operating regulated so that the reference voltage and oscillator remain constant. junction temperature range are assured by design, characterization and Actual minimum input voltage to maintain a regulated output will depend correlation with statistical process controls. The LT1956IFE/LT1956IFE-5/ upon output voltage and load current. See Applications Information. LT1956IGN/LT1956IGN-5 are guaranteed over the full – 40°C to 125°C
Note 4:
This is the minimum voltage across the boost capacitor needed to operating junction temperature range. guarantee full saturation of the internal power switch.
Note 9:
Transconductance and voltage gain refer to the internal amplifier
Note 5:
Boost current is the current flowing into the BOOST pin with the exclusive of the voltage divider. To calculate gain and transconductance, pin held 5V above input voltage. It flows only during switch on time. refer to the SENSE pin on fixed voltage parts. Divide values shown by the ratio V
Note 6:
Input supply current is the quiescent current drawn by the input OUT/1.219. pin when the BIAS pin is held at 5V with switching disabled. Bias supply
Note 10:
This IC includes overtemperature protection that is intended to current is the current drawn by the BIAS pin when the BIAS pin is held at protect the device during momentary overload conditions. Junction 5V. Total input referred supply current is calculated by summing input temperature will exceed 125°C when overtemperature protection is active. supply current (I Continuous operation above the specified maximum operating junction VIN) with a fraction of supply current (IBIAS): I temperature may impair device reliability. TOTAL = IVIN + (IBIAS)(VOUT/VIN) with VIN = 15V, VOUT = 5V, IVIN = 1.4mA, IBIAS = 2.9mA, ITOTAL = 2.4mA. 1956f 3