Datasheet LT3437 (Analog Devices) - 4

LT3437
ELECTRICAL CHARACTERISTICS The
●
denotes the specifications which apply over the –40
°
C to 140
°
C temperature range, otherwise specifications are at TJ = 25
°
C. VIN = 12V, SHDN = 12V, BIAS = 5V, FB = 1.25V, CSS/SYNC = 0V unless otherwise noted.
IVIN Supply Quiescent Current BIAS = 0V, FB = 1.15V, VC = 0.8V, SYNC = 2V 1.35 2 mA BIAS = 5V, FB = 1.15V, VC = 0.8V, SYNC = 2V 0.475 1 mA Minimum BIAS Voltage (Note 5) 2.7 3.15 V IBIASS BIAS Sleep Current (Note 4) ● 110 180 µA IBIAS BIAS Quiescent Current SYNC = 2V 0.75 1 mA Minimum Boost Voltage (Note 6) ISW = 500mA 1.8 2.5 V Input Boost Current (Note 7) ISW = 0.5A 11 16 mA ISW = 0.25A 8 13 mA VREF Reference Voltage (VREF) 3.3V < VVIN < 60V ● 1.212 1.25 1.288 V VVIN = 80V ● 1.190 1.25 1.288 V IFB FB Input Bias Current 50 200 nA EA Voltage Gain (Note 8) 900 V/V EA Voltage gm dI(VC)= ±10µA 650 µMho EA Source Current FB = 1.15V 15 35 55 µA EA Sink Current FB = 1.35V 15 30 55 µA VC to SW gm 1 A/V VC Switching Threshold VSYNC = 2V 500 mV VC High Clamp 1.5 1.75 2.1 V IPK SW Current Limit ● 400 650 900 mA SW VCESAT Switch Saturation Voltage ISW = 250mA ● 200 400 mV (Note 9) ISW = 500mA ● 400 800 mV Switching Frequency ● 140 200 240 kHz Maximum Duty Cycle 95 % Minimum SYNC Amplitude 1.5 2 V SYNC Frequency Range 240 500 kHz SYNC Input Impedance 50 kΩ ICSS CSS Current Threshold (Note 10) FB = 0V 4 10 16 µA
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings BIAS voltage above its minimum input voltage, a portion of the total may cause permanent damage to the device. Exposure to any Absolute quiescent current will be supplied by the BIAS pin. Supply sleep current is Maximum Rating condition for extended periods may affect device defined as the quiescent current during the “sleep” portion of Burst Mode reliability and lifetime. operation. See Applications Information for determining application supply
Note 2:
The LT3437EDD/LT3437EFE are guaranteed to meet performance currents. specifications from 0°C to 125°C junction temperature. Specifications over
Note 5:
Minimum BIAS voltage is the voltage on the BIAS pin when IBIAS is the –40°C to 125°C operating junction temperature range are assured by sourced into the pin. design, characterization and correlation with statistical process controls. The
Note 6:
This is the minimum voltage across the boost capacitor needed to LT3437IDD/LT3437IFE are guaranteed and tested over the full –40°C to guarantee full saturation of the internal power switch. 125°C operating junction temperature range. The LT3437HFE is also tested
Note 7:
Boost current is the current flowing into the BOOST pin with the pin to the LT3437 Electrical Characteristics table at 140°C operating junction held 3.3V above input voltage. It flows only during switch on time. temperature. High junction temperatures degrade operating lifetimes.
Note 3:
Minimum input voltage is defined as the voltage where switching
Note 8:
Gain is measured with a VC swing from 1.15V to 750mV. starts. Actual minimum input voltage to maintain a regulated output will
Note 9:
Switch saturation voltage guaranteed by correlation to wafer level depend upon output voltage and load current. See Applications Information. measurements for DD package parts.
Note 4:
Supply input current is the quiescent current drawn by the input
Note 10:
The CSS threshold is defined as the value of current sourced into the pin. Its typical value depends on the voltage on the BIAS pin and operating CSS pin which results in an increase in sink current from the VC pin. See the state of the LT3437. With the BIAS pin at 0V, all of the quiescent current Soft-Start section in Applications Information. required to operate the LT3437 will be provided by the VIN pin. With the 3437fc 4