Datasheet LTC7818 (Analog Devices) - 6

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ELECTRICAL CHARACTERISTICS The
l
indicates specifications which apply over the specified operating junction temperature range, otherwise specifications are for TA = 25°C, VBIAS=12V, RUN1,2,3>1.25V, EXTVCC=0V, VPRG3=FLOAT unless otherwise noted. (Note 2) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
PLLIN Input High Level l 2.2 V PLLIN Input Low Level l 0.5 V Spread Spectrum Frequency Range PLLIN/SPREAD = INTVCC (Relative to fOSC) Minimum Frequency –12 % Maximum Frequency +15 %
PGOOD1 and OV3 Outputs
PGOOD1 Voltage Low IPGOOD1 = 2mA 0.2 0.4 V PGOOD1 Leakage Current VPGOOD1 = 5V ±1 µA PGOOD1 Trip Level VFB1 Rising 7 10 13 % VFB1 Relative to Set Regulation Point Hysteresis 2.5 % VFB1 Falling –13 –10 –7 % Hysteresis 2.5 % PGOOD1 Delay for Reporting a Fault 25 µs OV3 Voltage Low IOV3 = 2mA 0.2 0.4 V OV3 Leakage Current VOV3 = 5V ±1 µA OV3 Trip Level VFB3 Rising 7 10 13 % VFB3 Relative to Set Regulation Point Hysteresis 2.5 %
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
Note 4:
The LTC7818 is tested in a feedback loop that servos VITH1,2,3 may cause permanent damage to the device. Exposure to any Absolute to a specified voltage and measures the resultant VFB1,2,3. The Maximum Rating condition for extended periods may affect device specifications at 0°C and 85°C are not tested in production and are reliability and lifetime. assured by design, characterization and correlation to production testing
Note 2:
The LTC7818 is tested under pulsed load conditions such at other temperatures (125°C for the LTC7818E/LTC7818I, 150°C for the that T LTC7818J/LTC7818H). J ≈ TA. The LTC7818E is guaranteed to meet specifications from 0°C to 85°C junction temperature. Specifications over the –40°C to
Note 5:
Dynamic supply current is higher due to the gate charge being 125°C operating junction temperature range are assured by design, delivered at the switching frequency. See Applications Information. characterization and correlation with statistical process controls. The
Note 6:
Rise and fall times are measured using 10% and 90% levels. Delay LTC7818I is guaranteed over the –40°C to 125°C operating junction times are measured using 50% levels. temperature range, the LTC7818J is guaranteed over the –40°C to 150°C
Note 7:
The minimum on-time condition is specified for an inductor operating junction temperature range, and the LTC7818H is guaranteed peak-to-peak ripple current > 40% of I over the –40°C to 150°C operating junction temperature range and is L(MAX) (See Minimum On-Time Considerations in the Applications Information section). tested at 150°C. High junction temperatures degrade operating lifetimes; operating lifetime is derated for junction temperatures greater than
Note 8:
This IC includes overtemperature protection that is intended to 125°C. Note that the maximum ambient temperature consistent with protect the device during momentary overload conditions. The maximum these specifications is determined by specific operating conditions in rated junction temperature will be exceeded when this protection is active. conjunction with board layout, the rated package thermal impedance Continuous operation above the specified absolute maximum operating and other environmental factors. The junction temperature (T junction temperature may impair device reliability or permanently damage J, in °C) is calculated from the ambient temperature (T the device. A, in °C) and power dissipation (P
Note 9:
Do not apply a voltage or current source to these pins. They must be D, in Watts) according to the formula: TJ = TA + (PD • θJA), where θJA (in °C/W) is the package thermal impedance. connected to capacitive loads only, otherwise permanent damage may occur.
Note 3:
When SENSE1– ≥ 3.2V or EXTVCC ≥ 4.8V, VBIAS supply current is transferred to these pins to reduce the total input supply quiescent current. SENSE1– bias current is reflected to the buck channel 1 input supply (VIN1) by the formula I – VIN1 = ISENSE1 • VOUT1/(VIN1 • η), where η is the efficiency. EXTVCC bias current is similarly reflected to a buck channel input supply when biased by a buck channel output. To minimize input supply current, select channel 1 to be the lowest output voltage greater than 3.2V and connect EXTVCC to the lowest output voltage greater than 4.8V. 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 Package Description Typical Application Related Parts