Datasheet LT3435 (Analog Devices) - 3

LT3435
ELECTRICAL CHARACTERISTICS The
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denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TJ = 25
°
C. VIN = 12V, SHDN = 12V, BIAS = 5V, FB/PGFB = 1.25V, CSS/SYNC = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
EA Source Current FB = 1.15V 20 40 55 µA EA Sink Current FB = 1.35V 15 30 40 µA VC to SW gm 6 A/V VC High Clamp FB = 1.15V 2.1 2.2 2.4 V IPK SW Current Limit ● 3 5.2 6.5 A Switch On Resistance (Note 9) ● 0.1 0.25 Ω Switching Frequency ● 425 500 575 kHz Maximum Duty Cycle 86 92 % Minimum SYNC Amplitude 1.5 2.0 V SYNC Frequency Range 575 700 kHz SYNC Input Impedance 45 kΩ ICSS CSS Current Threshold (Note 10) FB = 0V 7 13 20 µA IPGFB PGFB Input Current 25 100 nA VPGFB PGFB Voltage Threshold (Note 11) ● 88 90 92 % ICT CT Source Current (Note 11) 2 3.6 5.5 µA CT Sink Current (Note 11) 1 2 mA VCT CT Voltage Threshold (Note 11) 1.16 1.2 1.26 V PG Leakage (Note 11) 0.1 1 µA PG Sink Current (Note 11) PGFB = 1V, PG = 400mV 100 200 µA
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
Note 5:
Minimum BIAS voltage is the voltage on the BIAS pin when IBIAS is may cause permanent damage to the device. Exposure to any Absolute sourced into the pin. Maximum Rating condition for extended periods may affect device
Note 6:
This is the minimum voltage across the boost capacitor needed to reliability and lifetime. guarantee full saturation of the internal power switch.
Note 2:
The LT3435EFE is guaranteed to meet performance specifications
Note 7:
Boost current is the current flowing into the BOOST pin with the from 0°C to 125°C junction temperature. Specifications over the –40°C to pin held 3.3V above input voltage. It flows only during switch on time. 125°C operating junction temperature range are assured by design,
Note 8:
Gain is measured with a VC swing from 1.15V to 750mV. characterization and correlation with statistical process controls. The
Note 9:
Switch on resistance is calculated by dividing V LT3435IFE is guaranteed and tested over the full –40°C to 125°C IN to SW voltage by the forced current (3A). See Typical Performance Characteristics for the operating junction temperature range. graph of switch voltage at other currents.
Note 3:
Minimum input voltage is defined as the voltage where switching
Note 10:
The C starts. Actual minimum input voltage to maintain a regulated output will SS threshold is defined as the value of current sourced into the C depend upon output voltage and load current. See Applications SS pin which results in an increase in sink current from the VC pin. See the Soft-Start section in Applications Information. Information.
Note 11:
The PGFB threshold is defined as the percentage of V
Note 4:
Supply input current is the quiescent current drawn by the input REF voltage which causes the current source output of the C pin. Its typical value depends on the voltage on the BIAS pin and operating T pin to change from sinking (below threshold) to sourcing current (above threshold). When state of the LT3435. With the BIAS pin at 0V, all of the quiescent current sourcing current, the voltage on the C required to operate the LT3435 will be provided by the V T pin rises until it is clamped IN pin. With the internally. When the clamp is activated, the output of the PG pin will be set BIAS voltage above its minimum input voltage, a portion of the total to a high impedance state. When the C quiescent current will be supplied by the BIAS pin. Supply sleep current is T clamp is inactive the PG pin will be set active low with a current sink capability of 200µA. defined as the quiescent current during the “sleep” portion of Burst Mode operation. See Applications Information for determining application supply currents. 3435fa 3