RT8270 datasheet(3/12 Pages) RICHTEK

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RT8270

DS8270-01 March 2011

www.richtek.com

Electrical Characteristics

Parameter

Symbol

Test Conditions

Min

Typ

Max

Unit

Feedback Reference Voltage

VFB

4.75V

≤ VIN ≤ 22V

1.184

1.222

1.258

High Side Switch-On Resistance

RDS(ON)1

0.18

Low Side Switch-On Resistance

RDS(ON)2

Switch Leakage

VEN = 0V, VSW = 0V

μA

Current Limit

ILIM

Duty = 90%; VBOOT−SW = 4.8V

Current Sense Transconductance

GCS

Output Current to VCOMP

2.5

A/V

Error Amplifier Tansconductance

ΔIC = ±10μA

780

μA/V

Oscillator Frequency

fSW

1.2

MHz

Short Circuit Oscillation Frequency

VFB = 0V

440

kHz

Maximum Duty Cycle

DMAX

VFB = 0.8V

Minimum On-Time

tON

100

Under Voltage Lockout Threshold

Rising

4.2

4.5

Under Voltage Lockout Threshold

Hysteresis

300

En input Low Voltage

0.4

En input High Voltage

1.4

Enable Pull Up Current

μA

(VIN = 12V, TA = 25

°C unless otherwise specified)

Absolute Maximum Ratings (Note 1)

Supply Voltage, VIN ----------------------------------------------------------------------------------------- 23V

Switching Voltage, SW -------------------------------------------------------------------------------------

−0.3V to (VIN + 0.3V)

BOOT Voltage ------------------------------------------------------------------------------------------------ (VSW

− 0.3V) to (VSW + 6V)

All Other Voltage ---------------------------------------------------------------------------------------------

−0.3V to 6V

Power Dissipation, PD @ TA = 25°C

SOP-8 ---------------------------------------------------------------------------------------------------------- 0.833W

Package Thermal Resistance (Note 2)

SOP-8,

θJA ---------------------------------------------------------------------------------------------------- 120°C/W

Junction Temperature --------------------------------------------------------------------------------------- 150

°C

Lead Temperature (Soldering, 10 sec.) ----------------------------------------------------------------- 260

°C

Storage Temperature Range -------------------------------------------------------------------------------

−65°C to 150°C

ESD Susceptibility (Note 3)

HBM (Human Body Mode) --------------------------------------------------------------------------------- 2kV

MM (Machine Mode) ---------------------------------------------------------------------------------------- 200V

Recommended Operating Conditions

(Note 4)

Supply Voltage, VIN ----------------------------------------------------------------------------------------- 4.75V to 22V

Enable Voltage, VEN ----------------------------------------------------------------------------------------- 0V to 5.5V

Junction Temperature Range ------------------------------------------------------------------------------

−40°C to 125°C

Ambient Temperature Range ------------------------------------------------------------------------------

−40°C to 85°C

To be continued

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