Datasheet LTC3448 (Analog Devices) - 3

LTC3448
ELECTRICAL CHARACTERISTICS The
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denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25
°
C. VIN = 3.6V unless otherwise specified. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
IS Input DC Bias Current VIN = 3.6V (Note 5) Active Mode (Pulse Skip, No LRO) VFB = 0.5V or VOUT = 90%, ILOAD = 0A, 1.5MHz 250 375 µA VFB = 0.5V or VOUT = 90%, ILOAD = 0A, 2.25MHz 275 400 µA Linear Regulator Operation (LRO) ILOAD ≤ ILDO(ON) 32 43 µA Shutdown VRUN = 0V, VIN = 5.5V 0.1 1 µA fOSC Oscillator Frequency FREQ = Low, VIN = 3.6V ● 1.2 1.5 1.8 MHz FREQ = High ● 1.8 2.25 2.7 MHz fSYNC Synchronization Frequency (Note 6) 1.5 >4 MHz VTH(SYNC) SYNC Activation Input Threshold 1 1.3 V RPFET RDS(ON) of P-Channel FET ISW = 100mA 0.4 Ω RNFET RDS(ON) of N-Channel FET ISW = –150mA 0.35 Ω ILSW SW Leakage VRUN = 0V, VSW = 0V or 5V, VIN = 5V ±0.01 ±1 µA VRUNH RUN Threshold High ● 1.5 V VRUNL RUN Threshold Low ● 0.3 V IRUN RUN Leakage Current ● ±0.01 ±1 µA VFREQH FREQ Threshold High ● VIN – 1 V VFREQL FREQ Threshold Low ● 1 V IFREQ FREQ Leakage Current ● ±0.01 ±1 µA VMODEH MODE Threshold High ● VIN – 0.15 V VMODEL MODE Threshold Low ● 0.12 V IMODE MODE Leakage Current ● ±0.1 ±1 µA ISYNC SYNC Leakage Current ● ±0.01 ±1 µA ILDO(ON) LRO ON Load Current Threshold 2.2mH Inductor (Note 8) 3 5 mA ILDO(OFF) LRO OFF Load Current Threhold 8 11 17 mA
Note 1:
Absolute Maximum Ratings are those values beyond which the life
Note 6:
4MHz operation is guaranteed by design but is not production of a device may be impaired. tested and is subject to duty cycle limitations.
Note 2:
The LTC3448E is guaranteed to meet performance specifications
Note 7:
This IC includes overtemperature protection that is intended to from 0°C to 70°C. Specifications over the –40°C to 85°C operating protect the device during momentary overload conditions. Junction temperature range are assured by design, characterization and correlation temperature will exceed 125°C when overtemperature is active. Continu- with statistical process controls. ous operation above the specified maximum operating junction tempera-
Note 3:
T ture may impair device reliability. J is calculated from the ambient temperature TA and power dissipation PD according to the following formula:
Note 8:
The load current below which the switching regulator turns off and T the LDO turns on is, to first order, inversely proportional to the value of J = TA + (PD)(43°C/W)
Note 4:
The LTC3448 is tested in a proprietary test mode that connects the inductor. This effect is covered in more detail in the Operation section. V This parameter is not production tested but is guaranteed by design. FB to the output of the error amplifier.
Note 5:
Dynamic supply current is higher due to the gate charge being
Note 9:
For 2.5V < VIN < 2.7V the output voltage is limited to VIN – 0.7V delivered at the switching frequency. LRO is “linear regulator operation.” to ensure regulation in linear regulator mode. This parameter is not production tested but is guaranteed by design. 3448f 3