RT8004A 데이터 시트보기 (PDF) - Richtek Technology

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RT8004A

4.5A, 4MHz, Synchronous Step-Down Regulator

Richtek Technology 

RT8004A

Low Supply Operation

The RT8004A is designed to operate down to an input supply voltage of 2.7V. One important consideration at low input

supply voltages is that the RDS(ON) of the P-MOSFET and N-MOSFET power switches increases. The user should

calculate the power dissipation when the RT8004A is used at 100% duty cycle with low input voltages to ensure that

thermal limits are not exceeded.

Slope Compensation and Inductor Peak Current

Slope compensation provides stability in constant frequency architectures by preventing subharmonic oscillations at

duty cycles greater than 50%. It is accomplished internally by adding a compensating ramp to the inductor current

signal. Normally, the maximum inductor peak current is reduced when slope compensation is added. In the RT8004A,

however, separated inductor current signals are used to monitor over current condition and minimum peak current. This

keeps the maximum output current and minimum peak current relatively constant regardless of duty cycle.

Short Circuit Protection

When the output is shorted to ground, the inductor current decays very slowly during a single switching cycle. A current

runaway detector is used to monitor inductor current. As current increases beyond the control of current loop, switching

cycles will be skipped to prevent current runaway from occurring.

Absolute Maximum Ratings (Note 1)

z Supply Input Voltage --------------------------------------------------------------------------------------------- −0.3V to 6V

z LX Pin Switch Voltage ------------------------------------------------------------------------------------------- −0.3V to (PVDD + 0.3V)

z Other I/O Pin Voltages ------------------------------------------------------------------------------------------ −0.3V to (VDD + 0.3V)

z Power Dissipation, PD @ TA = 25°C

TSSOP-16 (Exposed Pad) ------------------------------------------------------------------------------------- 2.128W

VQFN-16L 4x4 ---------------------------------------------------------------------------------------------------- 1.852W

z Package Thermal Resistance (Note 2)

TSSOP-16 (Exposed Pad), θJA ------------------------------------------------------------------------------- 45°C/W

TSSOP-16 (Exposed Pad), θJC ------------------------------------------------------------------------------- 30°C/W

VQFN-16L 4x4, θJA ----------------------------------------------------------------------------------------------- 54°C/W

VQFN-16L 4x4, θJC ---------------------------------------------------------------------------------------------- 7°C/W

z Lead Temperature (Soldering, 10 sec.) ---------------------------------------------------------------------- 260°C

z Junction Temperature -------------------------------------------------------------------------------------------- 150°C

z Storage Temperature Range ----------------------------------------------------------------------------------- −65°C to 150°C

z ESD Susceptibility (Note 3)

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

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

Recommended Operating Conditions (Note 4)

z Supply Input Voltage --------------------------------------------------------------------------------------------- 2.7V to 5.5V

z Ambient Temperature Range ----------------------------------------------------------------------------------- −40°C to 85°C

z Junction Temperature Range ----------------------------------------------------------------------------------- −40°C to 125°C

DS8004A-03 March 2011

www.richtek.com

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