Datasheet LTC7817 (Analog Devices) - 6

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ELECTRICAL CHARACTERISTICS Note 1:
Stresses beyond those listed under Absolute Maximum Ratings when biased by a buck channel output. To minimize input supply current, may cause permanent damage to the device. Exposure to any Absolute select channel 1 to be the lowest output voltage greater than 3.2V and Maximum Rating condition for extended periods may affect device connect EXTVCC to the lowest output voltage greater than 4.8V. reliability and lifetime.
Note 4:
The LTC7817 is tested in a feedback loop that servos VITH1,2,3
Note 2:
The LTC7817 is tested under pulsed load conditions such to a specified voltage and measures the resultant VFB1,2,3. The that TJ ≈ TA. The LTC7817E is guaranteed to meet specifications from specifications at 0°C and 85°C are not tested in production and are 0°C to 85°C junction temperature. Specifications over the –40°C to assured by design, characterization and correlation to production testing 125°C operating junction temperature range are assured by design, at other temperatures (125°C for the LTC7817E/LTC7817I, 150°C for the characterization and correlation with statistical process controls. The LTC7817J/LTC7817H) LTC7817I is guaranteed over the –40°C to 125°C operating junction
Note 5:
Dynamic supply current is higher due to the gate charge being temperature range, the LTC7817J is guaranteed over the –40°C to 150°C delivered at the switching frequency. See Applications Information. operating junction temperature range, and the LTC7817H is guaranteed
Note 6:
Rise and fall times are measured using 10% and 90% levels. Delay over the –40°C to 150°C operating junction temperature range. High times are measured using 50% levels. junction temperatures degrade operating lifetimes; operating lifetime is derated for junction temperatures greater than 125°C. Note that the
Note 7:
The minimum on-time condition is specified for an inductor maximum ambient temperature consistent with these specifications is peak-to-peak ripple current > 40% of IL(MAX) (See Minimum On-Time determined by specific operating conditions in conjunction with board Considerations in the Applications Information section). layout, the rated package thermal impedance and other environmental
Note 8:
This IC includes overtemperature protection that is intended to factors. The junction temperature (T protect the device during momentary overload conditions. The maximum J, in °C) is calculated from the ambient temperature (T rated junction temperature will be exceeded when this protection is active. A, in °C) and power dissipation (PD, in Watts) according to the formula: T Continuous operation above the specified absolute maximum operating J = TA + (PD • θJA), where θJA (in °C/W) is the package thermal impedance. junction temperature may impair device reliability or permanently damage
Note 3:
When SENSE1– ≥ 3.2V or EXTV the device. CC ≥ 4.8V, VBIAS supply current is transferred to these pins to reduce the total input supply quiescent current.
Note 9:
Do not apply a voltage or current source to these pins. They must SENSE1– bias current is reflected to the buck channel 1 input supply (V be connected to capacitive loads only, otherwise permanent damage may IN1) by the formula I – occur. VIN1 = ISENSE1 • VOUT1/(VIN1 • η), where η is the efficiency. EXTVCC bias current is similarly reflected to a buck channel input supply Rev 0 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 Applications Information Typical Applications Typical Application Related Parts