Datasheet LT8705 (Analog Devices) - 6

LT8705
e lecTrical characTerisTics The
l
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 12V, SHDN = 3V unless otherwise noted. (Note 3) PARAMETER CONDITIONS MIN TYP MAX UNITS
BG2 Off to TG2 On Delay CLOAD = 3300pF Each Driver 80 ns Minimum On-Time for Main Switch in Boost Operation Switch M3, CLOAD = 3300pF 265 ns (tON(M3,MIN)) Minimum On-Time for Synchronous Switch in Buck Switch M2, CLOAD = 3300pF 260 ns Operation (tON(M2,MIN)) Minimum Off-Time for Main Switch in Steady-State Boost Switch M3, CLOAD = 3300pF 245 ns Operation Minimum Off-Time for Synchronous Switch in Switch M2, CLOAD = 3300pF 245 ns Steady-State Buck Operation
Oscillator
Switch Frequency Range SYNCing or Free Running 100 400 kHz Switching Frequency, fOSC RT = 365k l 102 120 142 kHz RT = 215k l 170 202 235 kHz RT = 124K l 310 350 400 kHz SYNC High Level for Synchronization l 1.3 V SYNC Low Level for Synchronization l 0.5 V SYNC Clock Pulse Duty Cycle VSYNC = 0V to 2V 20 80 % Recommended Minimum SYNC Ratio fSYNC/fOSC 3/4 CLKOUT Output Voltage High 1mA Out of CLKOUT Pin 2.3 2.45 2.55 V CLKOUT Output Voltage Low 1mA Into CLKOUT Pin 25 100 mV CLKOUT Duty Cycle TJ = –40°C 22.7 % TJ = 25°C 44.1 % TJ = 125°C 77 % CLKOUT Rise Time CLOAD = 200pF 30 ns CLKOUT Fall Time CLOAD = 200pF 25 ns CLKOUT Phase Delay SYNC Rising to CLKOUT Rising, fOSC = 100kHz l 160 180 200 Deg
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
Note 5:
This specification not applicable in the FE38 package. may cause permanent damage to the device. Exposure to any Absolute
Note 6:
Do not apply a voltage or current source to these pins. They must Maximum Rating condition for extended periods may affect device be connected to capacitive loads only, otherwise permanent damage may reliability and lifetime. occur.
Note 2:
Do not force voltage on the VC pin.
Note 7:
Negative voltages on the SW1 and SW2 pins are limited, in an
Note 3:
The LT8705E is guaranteed to meet performance specifications application, by the body diodes of the external NMOS devices, M2 and from 0°C to 125°C junction temperature. Specifications over the –40°C M3, or parallel Schottky diodes when present. The SW1 and SW2 pins to 125°C operating junction temperature range are assured by design, are tolerant of these negative voltages in excess of one diode drop below characterization and correlation with statistical process controls. The ground, guaranteed by design. LT8705I is guaranteed over the full –40°C to 125°C junction temperature
Note 8:
This IC includes overtemperature protection that is intended range. The LT8705H is guaranteed over the full –40°C to 150°C operating to protect the device during momentary overload conditions. Junction junction temperature range. The LT8705MP is guaranteed over the full temperature will exceed the maximum operating junction temperature –55°C to 150°C operating junction temperature range. Operating lifetime is when overtemperature protection is active. Continuous operation above derated at junction temperatures greater than 125°C. the specified maximum operating junction temperature may impair device
Note 4:
Rise and fall times are measured using 10% and 90% levels. Delay reliability. times are measured using 50% levels. 8705ff 6 For more information www.linear.com/LT8705 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts