Document
RT8110A
Wide Input Range Synchronous Buck DC/DC PWM Controller
General Description
The RT8110A is a fixed-frequency PWM controller with integrated MOSFET drivers for single power rail synchronous single-phase buck converter. This part features an internal regulator that allows wide input voltage range operation. The RT8110A utilizes voltage-mode control with internal compensation to simplify the converter design. An internal 0.8V reference voltage allows low output voltage application. The switching frequency is fixed at 600kHz to reduce the external passive component size to save board space. The RT8110A provides under voltage protection, current limit, over current protection and over temperature protection. The low-side MOSFET RDS(ON) is used to sense the inductor current for over current protection.
Features
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10V to 23V Wide Input Voltage Range 0.8V Internal Reference Internal Soft Start High DC Gain Voltage Mode PWM Control Fixed 600kHz Switching Frequency Fast Transient Response Fully Dynamic 0 to 80% Duty Cycle Over Current Protection Under Voltage Protection Over Temperature Protection RoHS Compliant and 100% Lead (Pb)-Free
Applications
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Ordering Information
RT8110A Package Type SP : SOP-8 (Exposed Pad-Option 1) Operating Temperature Range P : Pb Free with Commercial Standard G : Green (Halogen Free with Commercial Standard)
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Set-top Box Power Supplies PC Subsystem Power Supplies Cable Modems, DSL Modems DSP and Core Communication Processor Power Supplies Memory Power Supplies Personal Computer Peripherals Industrial Power Supplies Low Voltage Distributed Power Supplies
Note : Richtek Pb-free and Green products are :
Pin Configurations
(TOP VIEW)
PHASE UGATE GND LGATE 2 3 4 8 GND 6 9 5 7 BOOT VIN FB VCC
`RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.
`Suitable for use in SnPb or Pb-free soldering processes.
SOP-8 (Exposed Pad)
DS8110A-00 May 2009
www.richtek.com 1
Free Datasheet http://www.datasheet4u.com/
RT8110A
Typical Application Circuit
VIN
+
C2
D
C4
CIN
RT8110A 5 VCC BOOT 8 C1 UGATE 2 7 R3 C3 6 FB R1 R2 VIN PHASE 1
CBOOT Q1
L VOUT COUT C5
+
LGATE 4 3, Exposed Pad (9) GND
Q2
Functional Pin Description
Pin No. 1 2 Pin Name PHASE UGATE Pin Function Switching Node of the Buck Converter. This pin is also used to monitor the voltage drop across the low-side MOSFET for over current protection. Gate Drive Pin for High-Side MOSFET. Signal and Power Ground of the IC. All voltage levels are referenced with respect to this pin. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Gate Drive Pin for Low-Side MOSFET. Internal Regulator Output Pin, typically 5.5V. VIN is regulated to VCC by the internal regulator. VCC is the main bias supply of the IC. This pin also provides power for the low-side MOSFET gate driver. Connect a ceramic capacitor to this pin. The voltage at this pin is monitored for power on reset (POR). Inverting Input of the Error Amplifier. This pin is connected to the joint of output voltage divider resistors to set the output voltage. The voltage at this pin is also monitored for under voltage protection. This pin is internally connected to the collector of integrated BJT, which is designed to withstand 23V to provide a regulated 5.5V voltage to VCC pin. This pin provides power to the high-side MOSFET gate driver. A bootstrap circuit is used to drive the high-side MOSFET.
3, GND 9 (Exposed Pad) 4 5 LGATE VCC
6 7 8
FB VIN BOOT
www.richtek.com 2
DS8110A-00 May 2009
Free Datasheet http://www.datasheet4u.com/
RT8110A
Function Block Diagram
VIN 5k VCC Regulator VCC PowerOn Reset POR 0.8VREF 0.5V + SS S1L + +Gm EO + PWM Gate Control Logic UVP Soft-Start and Fault Logic OC + + PH_M IOC ROC PHASE VCC
1.5V UGATE BOOT LGATE GND
VCC
FB
Oscillator
DS8110A-00 May 2009
www.richtek.com 3
Free Datasheet http://www.datasheet4u.com/
RT8110A
Absolute Maximum Ratings
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(Note 1) 7V 30V −3V to 24V 30V 0.3V to 7V 1.333W 75°C/W 15°C/W 150°C 260°C −65°C to 150°C 2kV 200V
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Supply Voltage, VCC -----------------------------------------------------------------------------------------------------Supply Voltage, VIN ------------------------------------------------------------------------------------------------------PHASE ---------------------------------------------------------------------------------------------------------------------BOOT -----------------------------------------------------------------------------------------------------------------------Input/Output Voltage -----------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C SOP-8 (Exposed Pad) -------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 4) SOP-8 (Exposed Pad), θJA ----------------------------------------------------.