RT9727A N-MOSFET Load Switch Controller General Description Features The RT9727A is a load switch controller to control the external N-MOSFET load switch. The input voltage range of the RT9727A is from 6V to 25V. The RT9727A adopts the constant power discharge method to discharge the residual storages. Besides, the RT9727A also provides enable control function and over temperature protection function. z Driver N-MOSFET Load Switch z Input Voltage Range : 6V to 25V Constant Power Discharge Over Temperature Protection Enable Control RoHS Compliant and Halogen Free The RT9727A is available in a SC-70-6 package. z z z z Applications z Notebook Computers Ordering Information RT9727A Pin Configurations Package Type U6 : SC-70-6 Lead Plating System G : Green (Halogen Free and Pb Free) (TOP VIEW) EN DC2 DC1 6 5 4 2 3 GND CT Note : Richtek products are : ` VCC RoHS compliant and compatible with the current require- SC-70-6 ments of IPC/JEDEC J-STD-020. ` Suitable for use in SnPb or Pb-free soldering processes. Typical Application Circuit Marking Information For marking information, contact our sales representative directly or through a Richtek distributor located in your area. 5V Source 1 VCC VCC C1 Chip Enable CT 3 DC2 5 Q1 To Systrm C3 RT9727A 6 EN 2 GND DC1 4 To Systrm C2 DS9727A-01 April 2011 3V Source Q2 C4 www.richtek.com 1 RT9727A Function Block Diagram VCC Regulator EN Bias CT Thermal Protection Gate Control DC2 Gate Control DC1 GND Functional Pin Description Pin No. Pin Name Pin Function 1 VCC Power Supply Input. 2 GND Ground. 3 CT Current Source Output. There is an internal 10μA current source from VCC to CT. 4 DC1 Discharge Path when EN Pulls Low. 5 DC2 Discharge Path when EN Pulls Low. 6 EN www.richtek.com 2 Chip Enable (Active High). Enable Control of the Internal 10μA current source and DCx discharge. DS9727A-01 April 2011 RT9727A Absolute Maximum Ratings z z z z z z z z (Note 1) VCC, CT to GND ----------------------------------------------------------------------------------------------------------EN, DC1, DC2 to GND ---------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C SC-70-6 ---------------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) SC-70-6, θJA ---------------------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Mode) ---------------------------------------------------------------------------------------------MM (Machine Mode) ------------------------------------------------------------------------------------------------------ Recommended Operating Conditions z z z −0.3V to 28V −0.3V to 6V 0.3W 333°C/W 260°C 150°C −65°C to 150°C 2kV 200V (Note 4) Supply Input Voltage, VCC ----------------------------------------------------------------------------------------------- 6V to 25V Junction Temperature Range -------------------------------------------------------------------------------------------Ambient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C −40°C to 85°C Electrical Characteristics (VCC = 10V, VEN = 5V, TA = 25°C, unless otherwise specified) Parameter Symbol Shutdown Current ISHDN Test Conditions VCC = 6V to 25V, EN = Low, DC1 and DC2 = 0 Quiescent Current IQ VCC = 6V to 25V, EN = High Power On Reset Threshold VCCR_TH VCC Rising Power On Reset Hysteresis VCC_hys Min Typ Max Unit -- 5 10 μA -- 40 65 μA 3.8 4.2 4.6 V -- 0.25 -- V CT Output CT Source Current ICTsr EN = High, CT = 0V 7 10 13 μA CT Sink Current ICTsk EN = Low, CT = 0.5V 200 -- -- μA EN = Low, DCx = 5V 18 -- -- EN = Low, DCx = 3.3V 20 -- -- EN = Low, DCx = 1.6V 50 -- -- Discharge Current Discharge Current IDCx mA Thermal Shutdown Thermal Shutdown tSHDN -- 160 -- °C Thermal Shutdown Hysteresis tSHDN_hys -- 20 -- °C Rising 2.4 -- -- Falling -- -- 0.8 Logic Input EN Threshold Voltage Logic-High Logic-Low DS9727A-01 April 2011 VIH VIL V www.richtek.com 3 RT9727A Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2. θJA is measured in the natural convection at TA = 25°C on a low effective thermal conductivity single layer test board of JEDEC 51-3 thermal measurement standard. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. www.richtek.com 4 DS9727A-01 April 2011 RT9727A Typical Operating Characteristics Quiescent Current vs. Input Voltage Shutdown Current vs. Input Voltage 10 Shutdown Current (μA)1 Quiescent Current (μA) 50 48 46 44 42 VEN = 5V 40 5 7 9 11 13 15 17 19 21 23 8 6 4 2 VEN = 0.5V 0 5 25 7 9 11 17 19 21 23 25 Shutdown Current vs. Temperature Quiescent Current vs. Temperature 60 10 Shutdown Current (μA)1 Quiescent Current (μA) 15 Input Voltage (V) Input Voltage (V) 55 VCC = 25V 50 VCC = 6V 45 40 VEN = 5V 35 -50 -25 0 25 50 75 100 8 6 VCC = 25V VCC = 6V 4 2 VEN = 0.5V 0 125 -50 -25 0 Temperature (°C) 25 50 75 100 125 Temperature (°C) CT Sink Current vs. Input Voltage CT Source Current vs. Input Voltage 13 147.0 CT Sink Current (μA) 12 CT Source Current (μA) 13 11 10 9 8 146.6 146.2 145.8 145.4 VEN = 5V 7 VEN = 0V, VCT = 0.5V 145.0 5 7 9 11 13 15 17 19 Input Voltage (V) DS9727A-01 April 2011 21 23 25 5 7 9 11 13 15 17 19 21 23 25 Input Voltage (V) www.richtek.com 5 RT9727A CT Source Current vs. Temperature CT Sink Current vs. Temperature 13 200 180 CT Sink Current (μA) CT Source Current (μA) VCC = 25V 12 11 VCC = 6V 10 9 8 160 VCC = 25V 140 VCC = 6V 120 100 VEN = 5V 7 -50 -25 0 25 50 75 100 VEN = 0V, VCT = 0.5V 80 125 -50 -25 0 Temperature (°C) Discharge Current vs. Temperature 50 75 100 125 VDCx Discharge Characteristic 6 70 System Residual Voltage (V)1 80 Discharge Current (mA) 25 Temperature (°C) VDCx = 1.6V 60 50 40 VDCx = 3.3V 30 VDCx = 5V 20 10 VEN = 0V 0 -50 -25 0 25 50 75 100 125 5 4 3 2 1 COUT = 300μF 0 0 20 40 60 80 100 Time (ms) Temperature (°C) Discharge Current vs. System Residual Voltage VDCx Discharge Current (mA) 70 60 50 40 30 20 10 VEN = 0V, COUT = 300μF 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 System Residual Voltage (V) www.richtek.com 6 DS9727A-01 April 2011 RT9727A Applications Information Enable & POR Power-On reset (POR) occurs when the input voltage rises above to approximately 4.5V, the RT9727A will be turned on once the EN pin voltage is higher than 2.4V. After the RT9727A is turned on, there is 10μA (typ.) current flows from CT pin to the gate of the external MOSFET, while both DCx pin discharge MOSFET are off. Discharge Operation When EN is low, the RT9727A will discharge the system residual voltage using internal MOSFET connected between the DCx and GND, while CT pin is pulled low. The discharge current depends on the voltage at the DCx pin. While both of the voltages at the DC1 and DC2 pins are lower than 0.5V, the RT9727A will fully turn the internal MOSFET on to pull the DCx pins low. Thermal Protection The RT9727A provides thermal shutdown detection to protect the device from over-heating in discharge mode. Once the junction temperature reaches 160°C, the RT9727A will stop discharging until the junction temperature is recovered. Thermal Considerations For continuous operation, do not exceed absolute maximum operation junction temperature. The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of surroundings airflow and temperature difference between junction to ambient. The maximum power dissipation can be calculated by following formula : DS9727A-01 April 2011 PD(MAX) = (TJ(MAX) − TA) / θJA Where T J(MAX) is the maximum operation junction temperature, TA is the ambient temperature and the θJA is the junction to ambient thermal resistance. For recommended operating condition specification of RT9727A, the maximum junction temperature is 125°C and TA is the maximum ambient temperature. The junction to ambient thermal resistance θJA is layout dependent. For SC-70-6 packages, the thermal resistance θJA is 333°C/W on the standard JEDEC 51-3 single layer thermal test board. The maximum power dissipation at TA = 25°C can be calculated by following formula : PD(MAX) = (125°C − 25°C) / (333°C /W) = 0.3W for SC-70-6 package The maximum power dissipation depends on operating ambient temperature for fixed T J(MAX) and thermal resistance θJA . For RT9727A package, the Figure 1 of derating curves allows the designer to see the effect of rising ambient temperature on the maximum power dissipation allowed. 0.40 Maximum Power Dissipation (W)1 The RT9727A is a load switch with wide input voltage range from 6V to 25V. It provides two paths for discharging the residual voltage when system shutdown. Besides, the external MOSFET switch On/Off can be controlled by an internal current source from the CT pin to the gate of the MOSFET switch. A novel control is implemented for nearly constant power to discharge the system residual voltages. Single Layer PCB 0.35 0.30 0.25 SC-70-6 0.20 0.15 0.10 0.05 0.00 0 25 50 75 100 125 Ambient Temperature (°C) Figure 1. Derating Curves for RT9727A Package www.richtek.com 7 RT9727A Layout Consideration For best performance of the RT9727A, the following guidelines must be followed : ` Input capacitor should be placed close to the IC and connected to ground plane to reduce noise coupling. ` Keep the main current traces as short and wide as possible. The input capacitor should be placed as close as possible to the IC. VCC 6 EN CIN GND 2 5 DC2 CT 3 4 DC1 The main current trace should be as short and wide as possible. Figure 2. PCB Layout Guide www.richtek.com 8 DS9727A-01 April 2011 RT9727A Outline Dimension H D L C B b A A1 e Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 0.800 1.100 0.031 0.044 A1 0.000 0.100 0.000 0.004 B 1.150 1.350 0.045 0.054 b 0.150 0.400 0.006 0.016 C 1.800 2.450 0.071 0.096 D 1.800 2.250 0.071 0.089 e 0.650 0.026 H 0.080 0.260 0.003 0.010 L 0.210 0.460 0.008 0.018 SC-70-6 Surface Mount Package Richtek Technology Corporation Richtek Technology Corporation Headquarter Taipei Office (Marketing) 5F, No. 20, Taiyuen Street, Chupei City 5F, No. 95, Minchiuan Road, Hsintien City Hsinchu, Taiwan, R.O.C. Taipei County, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Tel: (8862)86672399 Fax: (8862)86672377 Email: [email protected] Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek. DS9727A-01 April 2011 www.richtek.com 9