Datasheet LTC3851A (Analog Devices) - 4

LTC3851A
elecTrical characTerisTics The
l
denotes the specifications which apply over the specified operating temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = 15V, VRUN = 5V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS INTVCC Linear Regulator
VINTVCC Internal VCC Voltage 6V < VIN < 38V 4.8 5 5.2 V VLDO INT INTVCC Load Regulation ICC = 0mA to 50mA 0.5 2 %
Oscillator and Phase-Locked Loop
fNOM Nominal Frequency RFREQ = 60k 460 500 540 kHz fLOW Lowest Frequency RFREQ = 160k 205 235 265 kHz fHIGH Highest Frequency RFREQ = 36k 690 750 810 kHz RMODE/PLLIN MODE/PLLIN Input Resistance 100 kΩ fMODE MODE/PLLIN Minimum Input Frequency VMODE = External Clock 250 kHz MODE/PLLIN Maximum Input Frequency VMODE = External Clock 750 kHz IFREQ Phase Detector Output Current Sinking Capability fMODE > fOSC –90 µA Sourcing Capability fMODE < fOSC 75 µA
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings may
Note 3:
TJ is calculated from the ambient temperature TA and power cause permanent damage to the device. Exposure to any Absolute Maximum dissipation PD according to the following formulas: Rating condition for extended periods may affect device reliability and lifetime. LTC3851AGN: TJ = TA + (PD • 110°C/W)
Note 2:
The LTC3851A is tested under pulsed load conditions such that LTC3851AUD: TJ = TA + (PD • 68°C/W) TA ≈ TJ. The LTC3851AE is guaranteed to meet performance specifications LTC3851AMSE: T from 0°C to 85°C junction temperature. Specifications over the –40°C J = TA + (PD • 40°C/W) to 125°C operating junction temperature range are assured by design,
Note 4:
The LTC3851A is tested in a feedback loop that servos VITH to a characterization and correlation with statistical process controls. The specified voltage and measures the resultant VFB. LTC3851AI is guaranteed to meet specifications over the –40°C to 125°C
Note 5:
Dynamic supply current is higher due to the gate charge being operating junction temperature range, the LTC3851AH is guaranteed delivered at the switching frequency. See Applications Information. over the –40°C to 150°C operating junction temperature range and the
Note 6:
Rise and fall times are measured using 10% and 90% levels. Delay LTC3851AMP is tested and guaranteed over the –55°C to 150°C operating times are measured using 50% levels. Rise and fall times are assured by junction temperature range. High junction temperatures degrade operating design, characterization and correlation with statistical process controls. lifetimes; operating lifetime is derated for junction temperatures greater
Note 7:
The minimum on-time condition is specified for an inductor than 125°C. Note that the maximum ambient temperature consistent with peak-to-peak ripple current ~40% of IMAX (see Minimum On-Time these specifications is determined by specific operating conditions in Considerations in the Applications Information section). conjunction with board layout, the rated package thermal impedance and
Note 8:
Guaranteed by design; not tested in production. other environmental factors.
Typical perForMance characTerisTics Efficiency vs Output Current Efficiency vs Output Current Efficiency vs Output Current and Mode and Mode and Mode
100 100 100 VIN = 12V 90 VOUT = 1.5V 90 90 BURST 80 80 80 BURST BURST 70 70 70 60 PULSE 60 60 PULSE SKIP PULSE SKIP 50 50 SKIP 50 CCM CCM 40 40 40 EFFICIENCY(%) CCM EFFICIENCY(%) EFFICIENCY (%) 30 30 30 20 20 20 VIN = 12V 10 10 VOUT = 3.3V 10 VIN = 12V FIGURE 11 CIRCUIT V 0 0 0 OUT = 5V 10 100 1000 10000 100000 10 100 1000 10000 100000 10 100 1000 10000 100000 LOAD CURRENT (mA) LOAD CURRENT (mA) LOAD CURRENT (mA) 3851A G01 3851A G02 3851A G03 3851afa 4 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts