Datasheet LTC7810 (Analog Devices) - 6

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ELECTRICAL CHARACTERISTICS The
l
denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25°C, VIN = 12V, RUN1,2 = 5V, EXTVCC = 0V, DRVSET = INTVCC unless otherwise noted. (Note 2) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
fSYNC Synchronizable Frequency Range PLLIN/SPREAD = External Clock l 75 720 kHz PLLIN Input High Level l 2.5 V PLLIN Input Low Level l 0.5 V Spread Spectrum Frequency Range (Relative PLLIN/SPREAD = INTVCC, RFREQ = 105kΩ to fOSC) Minimum Frequency –15 % Maximum Frequency +15 % Spread Spectrum Modulation Frequency PLLIN/SPREAD = INTVCC 4.5 kHz
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
Note 5:
Dynamic supply current is higher due to the gate charge being may cause permanent damage to the device. Exposure to any Absolute delivered at the switching frequency. See the Applications Information Maximum Rating condition for extended periods may affect device section. reliability and lifetime.
Note 6:
Rise and fall times are measured using 10% and 90% levels. Delay
Note 2:
The LTC7810 is tested under pulsed load conditions such that times are measured using 50% levels. TJ ≈ TA. The LTC7810E is guaranteed to meet specifications from
Note 7:
The minimum on-time condition is specified for an inductor 0°C to 85°C junction temperature. Specifications over the –40°C to peak-to-peak ripple current > 40% of IMAX (See Minimum On-Time 125°C operating junction temperature range are assured by design, Considerations in the Applications Information section). characterization and correlation with statistical process controls. The
Note 8:
This IC includes overtemperature protection that is intended to LTC7810I is guaranteed over the –40°C to 125°C operating junction protect the device during momentary overload conditions. The maximum temperature range and the LTC7810H is guaranteed over the –40°C to rated junction temperature will be exceeded when this protection is active. 150°C operating junction temperature range. High junction temperatures Continuous operation above the specified absolute maximum operating degrade operating lifetimes; operating lifetime is derated for junction junction temperature may impair device reliability or permanently damage temperatures greater than 125°C. Note that the maximum ambient the device. temperature consistent with these specifications is determined by specific operating conditions in conjunction with board layout, the rated
Note 9:
Do not apply a voltage or current source to the NDRV pin, other package thermal impedance and other environmental factors. The junction than tying NDRV to DRVCC when not used. If used it must be connected temperature (T to capacitive loads only (see DRVCC Regulators in the Applications J, in °C) is calculated from the ambient temperature (TA, in °C) and power dissipation (P Information section), otherwise permanent damage may occur. D, in Watts) according to the formula: TJ = TA + (P
Note 10:
Do not apply a voltage or current source to these pins. They must D • θJA), where θJA (in °C/W) is the package thermal impedance.
Note 3:
SENSE1– bias current is reflected to the input supply by the be connected to capacitive loads only, otherwise permanent damage may formula I – occur. VIN = ISENSE1 • VOUT1/(VIN • η), where η is the efficiency. EXTVCC bias current is similarly reflected to the input supply when biased by an
Note 11:
The minimum input supply operating range is dependent on the output greater than the EXTV DRV CC LDO Switchover Voltage (VCCOX). CC UVLO thresholds as determined by the DRVSET pin setting.
Note 4:
The LTC7810 is tested in a feedback loop that servos VITH1,2 to a specified voltage and measures the resultant VFB1,2. The specification at 85°C is not tested in production and is assured by design, characterization and correlation to production testing at other temperatures (125°C for the LTC7810E/LTC7810I, 150°C for the LTC7810H. Rev. A 6 For more information www.analog.com Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Main Control Loop Power and Bias Supplies (VIN, NDRV, EXTVCC, DRVCC, REGSD) Boost Supply and Dropout (BOOST and SW pins) Start-Up and Shutdown (RUN, TRACK/SS, OVLO Pins) Light Load Operation: Burst Mode Operation, Pulse Skipping or Forced Continuous Mode (MODE Pin) Frequency Selection, Spread Spectrum, and Phase-Locked Loop (FREQ and PLLIN/SPREAD Pins) Applications Information Current Sense Selection Low Value Resistor Current Sensing Inductor DCR Sensing Setting the Operating Frequency Selecting the Light-Load Operating Mode Inductor Value Calculation Inductor Core Selection Power MOSFET Selection CIN and COUT Selection Setting the Output Voltage RUN Pins and Overvoltage/Undervoltage Lockout Tracking and Soft-Start (TRACK/SS1, TRACK/SS2 Pins) Single Output Two-Phase Operation DRVCC Regulators Topside MOSFET Driver Supply (CB, DB) Burst Clamp Programming Fault Conditions: Current Limit and Current Foldback Fault Conditions: Overvoltage Protection (Crowbar) Fault Conditions: Overtemperature Protection Phase-Locked Loop and Frequency Synchronization Minimum On-Time Considerations Efficiency Considerations Checking Transient Response Design Example PC Board Layout Checklist PC Board Layout Debugging Typical Applications Package Description Revision History Typical Application Related Parts