LTC3772B datasheet(4/32 Pages) LINER

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LTC3852

3852f

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Oscillator and Phase-Locked Loop (Step-Down Regulator)

fNOM1

Nominal Frequency

RFREQ = 60k

460

500

540

kHz

fLOW1

Lowest Frequency

RFREQ = 160k

205

235

265

kHz

fHIGH1

Highest Frequency

RFREQ = 36k

690

750

810

kHz

fNOM2

Nominal Frequency

RFREQ = 60k (Note 7)

460

500

540

kHz

fLOW2

Lowest Frequency

RFREQ = 160k (Note 7)

205

235

265

kHz

fHIGH2

Highest Frequency

RFREQ = 36k (Note 7)

690

750

810

kHz

fMODE

MODE/PLLIN Minimum Input Frequency

MODE/PLLIN Maximum Input Frequency

MODE/PLLIN = External Clock

250

750

kHz

RMODE/PLLIN

MODE/PLLIN Input Resistance

100

kΩ

IFREQ

Phase Detector Output Current

Sinking Capability

Sourcing Capability

fMODE > fOSC

fMODE < fOSC

–90

μA

PGOOD Output

VPGL

PGOOD Voltage Low

IPGOOD = 2mA

0.1

0.3

IPGOOD

PGOOD Leakage Current

VPGOOD = 5V

±1

μA

VPG

PGOOD Trip Level

VFB with Respect to Regulated Voltage

VFB Ramping Negative

VFB Ramping Positive

–12

–10

–8

VPUMP Charge Pump Supply (VIN1 = 3.3V; VSHDN = 3.3V, VRUN = 0); CVIN1 = 4.7μF, CFLY = 2.2μF, CVPUMP = 4.7μF

VIN1

Input Voltage Range

2.7

5.5

VPUMP

Charge Pump Doubler Output Voltage

CFLY = 2.2μF

2.7V < VIN1 < 5.5V; IVPUMP = 1mA

4.8

5.05

5.3

ISHDN

Shutdown Pin Current

SHDN = 0V; VPUMP = 0V

μA

VRIPPLE

Output Ripple at VPUMP

IVPUMP = 50mA (Note 10)

mVP-P

fPUMP

Charge Pump Frequency

0.6

1.2

1.8

MHz

VIH

SHDN Input Threshold

1.3

VIL

SHDN Input Threshold

0.4

IIH

SHDN Input Current

–1

μA

IIL

SHDN Input Current

–1

μA

ROL

Effective Open-Loop Output Resistance

(Note 8)

VIN1 = 2.7V, VPUMP = 4.5V

ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at TA = 25°C (Note 2), VIN1 = 3.3V, VIN2 = 15V, VRUN = 3.3V, SHDN = 0V,

MODE/PLLIN = 0V unless otherwise noted.

Note 1: Stresses beyond those listed under Absolute Maximum Ratings may

cause permanent damage to the device. Exposure to any Absolute Maximum

Rating condition for extended periods may affect device reliability and lifetime.

Note 2: The LTC3852 is tested under pulsed load conditions such that

TJ ≈ TA. The LTC3852E is guaranteed to meet speciﬁcations from

0°C to 85°C junction temperature. Speciﬁcations over the –40°C to

125°C operating junction temperature range are assured by design,

characterization and correlation with statistical process controls. The

LTC3852I is guaranteed over the –40°C to 125°C operating junction

temperature range. TJ is calculated from the ambient temperature, TA and

power dissipation PD according to the following formula:

TJ = TA + (PD • 38°C/W)

Note 3: The LTC3852 is tested in a feedback loop that servos VITH to a

speciﬁed voltage and measures the resultant VFB.

Note 4: Dynamic supply current is higher due to the gate charge being

delivered at the switching frequency. See Applications information.

Note 5: Rise and fall times are measured using 10% and 90% levels. Delay

times are measured using 50% levels. Rise and fall times are assured by

design, characterization and correlation with statistical process controls.

Note 6: The minimum on-time condition is speciﬁed for an inductor

peak-to-peak ripple current equal to 40% of IMAX (see Minimum On-Time

Considerations in the Applications Information Section).

Note 7: VIN1 = 3.3V; Connect VPUMP, VIN2 and INTVCC together.

Note 8: ROL = (2VIN - VOUT)/IOUT

Note 9: VIN2 swept while not connected to VPUMP or INTVCC.

Note 10: Guaranteed by design, not tested in production.

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