Datasheet LT1976, LT1976B (Analog Devices) - 4

LT1976/LT1976B
ELECTRICAL CHARACTERISTICS The
●
denotes the specifications which apply over the full –40
°
C to 140
°
C operating temperature range, otherwise specifications are at TJ = 25
°
C. VIN = 12V, SHDN = 12V, BOOST = 15.3V, BIAS = 5V, FB/PGFB = 1.25V, CSS/SYNC = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
IPK SW Current Limit 2.4 A Switch On Resistance (Note 9) ● 0.2 0.6 Ω Switching Frequency BOOST = OPEN ● 150 200 260 kHz Maximum Duty Cycle 90 92 % Minimum SYNC Amplitude 1.5 2.0 V SYNC Frequency Range 230 600 kHz SYNC Input Impedance SYNC = 0.5V 85 kΩ ICSS CSS Current Threshold (Note 10) 7 13 20 μA IPGFB PGFB Input Current 25 100 nA VPGFB PGFB Voltage Threshold (Note 11) ● 87 90 93 % ICT CT Source Current (Note 11) ● 1.5 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) PG = 12V 0.1 1 μA PG Sink Current (Note 11) PGFB = 1V, PG = 400mV 120 200 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 LT1976EFE/LT1976BEFE are guaranteed to meet performance
Note 7:
Boost current is the current flowing into the BOOST pin with the specifications from 0°C to 125°C junction temperature. Specifications over pin held 3.3V above input voltage. It flows only during switch on time. the –40°C to 125°C operating junction temperature range are assured by
Note 8:
Gain is measured with a VC swing from 1.15V to 750mV. design, characterization and correlation with statistical process controls.
Note 9:
Switch on resistance is calculated by dividing V The LT1976IFE/LT1976BIFE/LT1976HFE are guaranteed and tested over IN to SW voltage by the forced current (1.5A LT1976, 1.2A LT1976B). See Typical Performance the full –40°C to 125°C operating junction temperature range. The Characteristics for the graph of switch voltage at other currents. LT1976HFE is also tested to the LT1976HFE electrical characteristics table at 140°C operating junction temperature. High junction temperatures
Note 10:
The CSS threshold is defined as the value of current sourced into degrade operating lifetimes. the CSS pin which results in an increase in sink current from the VC pin. See the Soft-Start section in Applications Information.
Note 3:
Minimum input voltage is defined as the voltage where switching starts. Actual minimum input voltage to maintain a regulated output will
Note 11:
The PGFB threshold is defined as the percentage of VREF voltage depend upon output voltage and load current. See Applications which causes the current source output of the CT pin to change from Information. sinking (below threshold) to sourcing current (above threshold). When sourcing current, the voltage on the C
Note 4:
Supply input current is the quiescent current drawn by the input T pin rises until it is clamped internally. When the clamp is activated, the output of the PG pin will be set pin. Its typical value depends on the voltage on the BIAS pin and operating to a high impedance state. When the C state of the LT1976. With the BIAS pin at 0V, all of the quiescent current T clamp is inactive the PG pin will be set active low with a current sink capability of 200μA. required to operate the LT1976 will be provided by the VIN pin. With the BIAS voltage above its minimum input voltage, a portion of the total quiescent current will be supplied by the BIAS pin. Supply sleep current for the LT1976 is defined as the quiescent current during the “sleep” portion of Burst Mode operation. See Applications Information for determining application supply currents. 1976bfg 4