® RT9745A Dual Channel, Low Resistance Load Switch General Description Features The RT9745A is a small, low RON, dual channel load switch with EN controlled pin. The product contains two NMOSFETs that can operate between an input voltage range of 0.8V to 5.5V. Also, it supports a maximum continuous current of 6A each channel. Each switch is independently controlled by EN pins (EN1 and EN2), which can directly interface with low-voltage control signals. Integrated Dual Channel Load Switch Input Voltage Range : 0.8V to 5.5V Low RON Resistance RON = 27mΩ Ω at VIN = 5V (VDD = 5V) RON = 27mΩ Ω at VIN = 3.6V (VDD = 5V) RON = 27mΩ Ω at VIN = 1.8V (VDD = 5V) 6A Maximum Continuous Switch Current Per Channel Low Quiescent Current 75μ μA (Both Channels) 55μ μA (Single Channel) Low Control Input Threshold Enables Use of 1.4V/ 1.8V/2.5V/3.3V Logics Configurable Rise Time Quick Output Discharge (QOD) Adaptive Discharge Current 14T-Lead WDFN Package with Thermal Pad The RT9745A is available in the WDFN-14TL 3x2 package with exposed pad for high power and heat dissipation. Ordering Information RT9745A Package Type QW : WDFN-14TL 3x2 (W-Type) Note : Lead Plating System G : Green (Halogen Free and Pb Free) Richtek products are : RoHS compliant and compatible with the current require- Applications ments of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. Marking Information 0P : Product Code W : Date Code 0PW UltrabookTM Notebooks/Netbooks Tablet PC Consumer Electronics Set-Top Boxes/Residential Gateways Telecom Systems Solid State Drives (SSD) Simplified Application Circuit VIN1 CIN1 Enable Dual Power Supply or Dual DC/DC Converter EN1 Enable EN2 RL1 SS1 CSS1 SS2 CSS2 VIN2 VOUT2 GND Copyright © 2014 Richtek Technology Corporation. All rights reserved. VOUT1 COUT1 VDD CIN2 DS9745A-00 August 2014 VOUT1 RT9745A VOUT2 COUT2 RL2 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT9745A Pin Configurations (TOP VIEW) VIN1 VIN1 EN1 VDD EN2 VIN2 VIN2 1 14 2 13 3 4 12 GND 5 6 7 11 10 15 9 8 VOUT1 VOUT1 SS1 GND SS2 VOUT2 VOUT2 WDFN-14TL 3x2 Functional Pin Description Pin No. Pin Name Pin Function 1, 2 VIN1 Input Voltage for Switch 1. Bypass this input with a ceramic capacitor to GND. Recommended voltage range for this pin for optimal RON performance is 0.8V to VDD. 3 EN1 Enable Control Input for Switch 1 (Active High). Do not leave floating. 4 VDD Charge Pump Voltage Input. Power supply to the device. Recommended voltage range for this pin is 2.5V to 5.5V. 5 EN2 Enable Control Input for Switch 2 (Active High). Do not leave floating. 6, 7 VIN2 Input Voltage for Switch 2. Bypass this input with a ceramic capacitor to GND. Recommended voltage range for this pin for optimal RON performance is 0.8V to VDD. 8, 9 VOUT2 Switch 2 Output. 10 SS2 Switch 2 Slew Rate Control. Can be left floating. 11, 15 (Exposed Pad) GND Ground. The Exposed pad should be soldered to a large PCB and connected to GND for maximum thermal dissipation. 12 SS1 Switch 1 Slew Rate Control. Can be left floating. VOUT1 Switch 1 Output. 13, 14 Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS9745A-00 August 2014 RT9745A Function Block Diagram VIN1 SS1 EN1 Control Logic VOUT1 VDD Charge Pump GND VOUT2 EN2 Control Logic SS2 VIN2 Operation The RT9745A contains two N-MOSFETs which controlled by EN pin independently. Charge Pump Enable Control Adjustable Rise Time Asserting ENx pin high enables the switch. Switch will turn on as the EN signal is higher than VENH, and turn off when the EN signal is lower than VENL. Thus, it can operate under low voltage logic, please refer to the electrical characteristics. This pin cannot be left floating and must be tied either high or low voltage for proper functionality. Connecting a capacitor to GND on the SSx pin sets the slew rate for each channel. It could also be used to prevent in-rush current. Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS9745A-00 August 2014 Provides sufficient bias voltage to both N-MOSFETs. is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT9745A Absolute Maximum Ratings (Note 1) VIN1, VIN2, EN1, EN2, VDD, VOUT1, VOUT2, SS1, SS2 ------------------------------------------------------Maximum Continuous Switch Current Per Channel, IMAX ------------------------------------------------------Maximum Pulsed Switch Current, Pulse <300μs, 2% Duty Cycle Per Channel, IPLS -------------------Power Dissipation, PD @ TA = 25°C WDFN-14TL 3x2 -----------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) WDFN-14TL 3x2, θJA ------------------------------------------------------------------------------------------------------WDFN-14TL 3x2, θJC -----------------------------------------------------------------------------------------------------Junction Temperature -----------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------------Storage Temperature Range --------------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Model) ----------------------------------------------------------------------------------------------CDM (Charged-Device Model) ------------------------------------------------------------------------------------------- Recommended Operating Conditions −0.3V to 6V 6A 8A 3.11W 32.1°C/W 6.3°C/W 150°C 260°C −65°C to 150°C 2kV 1kV (Note 4) VIN1,2, Input Voltage Range ---------------------------------------------------------------------------------------------VDD, Charge Pump Input Voltage Range -----------------------------------------------------------------------------VEN1,2, EN Voltage Range -----------------------------------------------------------------------------------------------Junction Temperature Range --------------------------------------------------------------------------------------------Ambient Temperature Range --------------------------------------------------------------------------------------------- 0.8V to VDD 2.5V to 5.5V 0V to VDD −40°C to 125°C −40°C to 85°C Electrical Characteristics (VIN = 0.8V to 5.5V, TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit EN Input Supply Input Voltage High-Level VENH 1.4 -- 5.5 Low-Level VENL 0 -- 0.5 -- -- 1 A Min Typ Max Unit -- 75 115 A ENx Pin Input Leakage Current IEN VEN = 5.5V V (VDD = 5V, VIN = 0.8V to VDD, TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Power Supplies and Currents VDD Quiescent Current (Both Channels) IIN(VDD, ON) IOUT1 = IOUT2 = 0A VIN1,2 = VEN1,2 = VDD = 5V IOUT1 = IOUT2 = 0A VDD Quiescent Current (Single Channel) IIN(VDD, ON) VIN1,2 = VEN1 = VDD = 5V, VEN2 = GND -- 55 -- A VDD Shutdown Current IIN(VDD, OFF) VEN1,2 = GND, VOUT1,2 = 0V -- -- 2 A Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 is a registered trademark of Richtek Technology Corporation. DS9745A-00 August 2014 RT9745A Parameter Symbol VIN1,2 Off-State Supply Current IIN(VIN, OFF) (Per Channel) Test Conditions Min Typ Max VIN1,2 = 5V -- -- 8 VIN1,2 = 3.3V -- -- 3 VIN1,2 = 1.8V -- -- 2 VIN1,2 = 0.8V -- -- 1 VIN = 5V -- 27 30 VIN = 3.3V -- 27 30 VIN = 1.8V -- 27 30 VIN = 1.5V -- 27 30 VIN = 1.2V -- 27 30 VIN = 0.8V -- 27 30 VEN = 0V, VIN = 5V, IOUT = 15mA -- 220 300 VEN1,2 = GND, VOUT1,2 = 0V Unit A Resistance Characteristics ON-State Resistance Output Pull-down Resistance RON RPD IOUT = 200mA, VDD = 5V m Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and 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 may affect device reliability. Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is measured at the exposed pad of the package. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS9745A-00 August 2014 is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RT9745A Typical Application Circuit VIN1 0.8V to 5.5V 1, 2 CIN1 CIN2 VIN1 3 EN1 VDD 2.5V to 5.5V 4 VDD Enable 5 EN2 6, 7 CIN3 13, 14 RT9745A Enable VIN2 0.8V to 5.5V VOUT1 COUT1 SS1 CSS1 SS2 10 CSS2 VOUT2 11, 15 (Exposed Pad) RL1 12 VIN2 CIN4 VOUT1 8, 9 VOUT2 COUT2 GND RL2 Timing Diagram VIN + - CIN Enable VOUT RT9745A EN VDD VOUT COUT RL GND Single Channel Shown for Clarity TEST CIRCUIT VEN 50% 50% VOUT 50% tf tr tOFF tON 50% 90% VOUT 10% 90% 10% tD Figure 1. Test Circuit and tON/tOFF Waveforms Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 is a registered trademark of Richtek Technology Corporation. DS9745A-00 August 2014 RT9745A Timing Characteristics Parameter Test Conditions Min Typ Max Unit VIN = EN = VDD = 5V, TA = 25C TON Turn-On Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 1220 -- TOFF Turn-Off Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 4 -- TR VOUT Rise Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 1350 -- TF VOUT Fall Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 3 -- TD ON Delay Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 400 -- s VIN = 0.8V, EN = VDD = 5V, TA = 25C TON Turn-On Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 580 -- TOFF Turn-Off Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 80 -- TR VOUT Rise Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 280 -- TF VOUT Fall Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 20 -- TD ON Delay Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 400 -- s VIN = EN = VDD = 3.3V, TA = 25C TON Turn-On Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 960 -- TOFF Turn-Off Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 6 -- TR VOUT Rise Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 940 -- TF VOUT Fall Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 3 -- TD ON Delay Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 400 -- s VIN = 0.8V, EN = VDD = 3.3V, TA = 25C TON Turn-On Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 560 -- TOFF Turn-Off Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 175 -- TR VOUT Rise Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 280 -- TF VOUT Fall Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 40 -- TD ON Delay Time RL = 10, COUT = 0.1F, CSS = 1000pF -- 400 -- Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS9745A-00 August 2014 s is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RT9745A Typical Operating Characteristics Quiescent Current vs. VDD Quiescent Current vs. VDD 50 Both Channels Quiescent Current (μA) 1 Quiescent Current (μA) 50 40 85°C 25°C −40°C 30 20 3.1 3.4 3.7 4 4.3 85°C 25°C −40°C 30 20 10 10 2.8 40 VIN1 = VIN2 = VDD, VEN1 = 0V, VEN2 = 5V, VOUT = Open, VUT1 = Off, VUT2 = On VIN1 = VIN2 = VDD, VEN1 = VEN2 = 5V, VOUT = Open, VUT1 = On, VUT2 = On 2.5 Single Channel 4.6 4.9 5.2 2.5 5.5 2.8 3.1 3.4 3.7 Off-State Supply Current (μA) Shut-Down Current (μA)1 0.08 0.06 85°C 0.04 −40°C 0.02 25°C 0.00 3.4 3.7 4 4.3 4.6 4.9 5.2 0.4 0.2 85°C 25°C −40°C 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5 VDD = 5.5V, VEN = 0V, VOUT = 0V 0.8 1.2 1.6 5.5 2 2.4 2.8 3.2 3.6 35 2.5V 1.8V 1.5V 1.2V 1.05V 0.8V Single Channel 40 30 25 20 15 4.4 4.8 5.2 5.6 On-Resistance vs. Temperature 45 On-Resistance (mΩ) On-Resistance (mΩ) 40 4 Input Voltage (V) Single Channel = = = = = = 5.5 0.3 On-Resistance vs. Temperature VIN VIN VIN VIN VIN VIN 5.2 Single Channel VDD (V) 45 4.9 0.5 Both Channels VIN1 = VIN2 = VDD, VEN1 = VEN2 = 0V, VOUT = 0V 3.1 4.6 Off-State Supply Current vs. Input Voltage Shut-Down Current vs. VDD 0.10 2.8 4.3 VDD (V) VDD (V) 2.5 4 VIN VIN VIN VIN VIN VIN 35 30 = = = = = = 0.8V 1.05V 1.2V 1.5V 1.8V 2.5V VIN VIN VIN VIN VIN = = = = = 3.3V 3.6V 4.2V 5V 5.5V 25 20 VDD = 2.5V, IOUT = −200mA -40 -15 10 15 35 60 Temperature (°C) Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 85 VDD = 5.5V, IOUT = −200mA -40 -15 10 35 60 85 Temperature (°C) is a registered trademark of Richtek Technology Corporation. DS9745A-00 August 2014 RT9745A On-Resistance vs. Input Voltage 45 On-Resistance vs. Input Voltage 45 Single Channel 40 On-Resistance (mΩ) On-Resistance (mΩ) 40 Single Channel 35 85°C 30 25°C 25 −40°C 20 0.8 1.14 1.48 85°C 30 25°C 25 −40°C 20 VDD = 2.5V, IOUT = −200mA 15 35 1.82 2.16 VDD = 5.5V, IOUT = −200mA 15 2.5 0.8 1.2 1.6 2 Input Voltage (V) VDD VDD VDD VDD VDD VDD 32 30 = = = = = = 360 2.5V 3.3V 3.6V 4.2V 5V 5.5V Discharge Resistance (Ω) On-Resistance (mΩ) Single Channel 34 28 26 24 22 2 2.4 2.8 3.2 3.6 4 Single Channel 320 280 240 85°C 25°C −40°C 200 160 120 80 40 TA = 25°C, IOUT = −200mA 0.8 1.2 1.6 VDD = 5.5V, VEN = 0V 0 0.8 1.2 1.6 4.4 4.8 5.2 5.6 2 4 4.4 4.8 5.2 5.6 On Delay Time vs. Input Voltage Output Voltage vs. Enable Voltage 600 Single Channel 550 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 VDD VDD VDD VDD VDD VDD = = = = = = 2.5V 3.3V 3.6V 4.2V 5V 5.5V On Delay Time (ms) Output Voltage (V) 2.4 2.8 3.2 3.6 Input Voltage (V) Input Voltage (V) 2.6 2.4 2.2 4.4 4.8 5.2 5.6 Discharge Resistance vs. Input Voltage 400 20 4 Input Voltage (V) On-Resistance vs. Input Voltage 36 2.4 2.8 3.2 3.6 500 −40°C 450 25°C 400 350 300 85°C 250 VIN = 2.5V, TA = 25°C 0 0.5 1 1.5 2 Enable Voltage (V) Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS9745A-00 August 2014 2.5 VDD = 2.5V, CSS = 1nF 200 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 Input Voltage (V) is a registered trademark of Richtek Technology Corporation. www.richtek.com 9 RT9745A On Delay Time vs. Input Voltage VDD = 5.5V, CSS = 1nF 550 On Delay Time (ms) On Delay Time vs. VDD 600 −40°C 500 On Delay Time (μs) 600 450 25°C 400 350 85°C 300 VIN1 = VIN2 = 2.5V, CSS = 1nF 500 −40°C 25°C 400 85°C 300 250 200 200 0.8 1.2 1.6 2 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6 2.5 2.8 3.1 3.4 Input Voltage (V) VDD = 2.5V, CSS = 1nF 4.6 4.9 5.2 5.5 VDD = 5.5V, CSS = 1nF 35 60 Off Fall Time (μs) Off Fall Time (μs) 4.3 Off Fall Time vs. Input Voltage 40 70 −40°C 25°C 85°C 50 40 30 20 10 30 25 85°C 25°C −40°C 20 15 10 5 0 0 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 0.8 1.2 1.6 2 Input Voltage (V) 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6 Input Voltage (V) Off Fall Time vs. VDD Off Time vs. Input Voltage 5 300 VIN = 2.5V, CSS = 1nF VDD = 2.5V, CSS = 1nF 250 4 85°C 3 25°C 2 −40°C Off Time (μs) Off Fall Time (μs) 4 VDD (V) Off Fall Time vs. Input Voltage 80 3.7 1 −40°C 25°C 85°C 200 150 100 50 0 0 2.5 2.8 3.1 3.4 3.7 4 4.3 4.6 4.9 5.2 VDD (V) Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 10 5.5 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 Input Voltage (V) is a registered trademark of Richtek Technology Corporation. DS9745A-00 August 2014 RT9745A Off Time vs. Input Voltage Off Time vs. VDD 20 150 15 85°C 25°C −40°C 90 Off Time (μs) Off Time (μs) 120 60 85°C 10 25°C 5 30 −40°C VDD = 5.5V, CSS = 1nF VIN = 2.5V, CSS = 1nF 0 0 0.8 1.2 1.6 2 2.4 2.8 3.2 3.6 4 2.5 4.4 4.8 5.2 5.6 2.8 3.1 3.4 Input Voltage (V) On Time vs. Input Voltage 4.3 4.6 4.9 5.2 5.5 On Time vs. Input Voltage 1600 900 800 700 25°C 600 85°C 500 0.8 1 1.2 1.4 1.6 1200 1000 800 600 VDD = 2.5V, CSS = 1nF 400 −40°C 25°C 85°C 1400 −40°C On Time (ms) On Time (ms) 4 VDD (V) 1000 1.8 2 2.2 2.4 VDD = 5.5V, CSS = 1nF 400 2.6 0.8 1.2 1.6 2 Input Voltage (V) On Rising Time (μs) 25°C 700 VIN = 2.5V, CSS = 1nF 2.5 2.8 3.1 3.4 3.7 4 4.3 4.6 4.9 5.2 VDD (V) Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS9745A-00 August 2014 −40°C 25°C 85°C 800 600 400 200 85°C 600 4.4 4.8 5.2 5.6 1000 −40°C 800 4 On Rising Time vs. Input Voltage On Time vs. VDD 900 2.4 2.8 3.2 3.6 Input Voltage (V) 1000 On Time (ms) 3.7 5.5 VDD = 2.5V, CSS = 1nF 0 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 Input Voltage (V) is a registered trademark of Richtek Technology Corporation. www.richtek.com 11 RT9745A On Rising Time vs. Input Voltage On Rising Time vs. VDD 2000 1000 1600 −40°C 25°C 85°C 1400 1200 On Rising Time (μs) On Rising Time (μs) 1800 1000 800 600 400 200 VDD = 5.5V, CSS = 1nF 0 0.8 1.2 1.6 2 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6 900 −40°C 800 25°C 700 85°C 600 VIN = 2.5V, CSS = 1nF 500 2.5 3.7 4 4.3 4.6 4.9 Turn-On Response Time EN1 (5V/Div) VOUT2 (500mV/Div) EN1 (5V/Div) VOUT2 (500mV/Div) VIN = 0.8V, VDD = 2.5V, CIN = 1μF, COUT = 0.1μF, RL = 10Ω EN2 (5V/Div) Time (500μs/Div) Turn-On Response Time Turn-On Response Time VOUT1 (5V/Div) EN1 (5V/Div) VOUT2 (2V/Div) EN1 (5V/Div) VOUT2 (5V/Div) VIN = 2.5V, VDD = 2.5V, CIN = 1μF, COUT = 0.1μF, RL = 10Ω Time (500μs/Div) Copyright © 2014 Richtek Technology Corporation. All rights reserved. EN2 (5V/Div) 5.2 5.5 VIN = 0.8V, VDD = 5V, CIN = 1μF, COUT = 0.1μF, RL = 10Ω Time (500μs/Div) VOUT1 (2V/Div) www.richtek.com 12 3.4 Turn-On Response Time VOUT1 (500mV/Div) EN2 (5V/Div) 3.1 VDD (V) VOUT1 (500mV/Div) EN2 (5V/Div) 2.8 Input Voltage (V) VIN = 5V, VDD = 5V, CIN = 1μF, COUT = 0.1μF, RL = 10Ω Time (500μs/Div) is a registered trademark of Richtek Technology Corporation. DS9745A-00 August 2014 RT9745A Turn-Off Response Time Turn-Off Response Time VOUT1 (500mV/Div) EN1 (5V/Div) VOUT1 (500mV/Div) EN1 (5V/Div) VOUT2 (500mV/Div) EN2 (5V/Div) VOUT2 (500mV/Div) EN2 (5V/Div) VIN = 0.8V, VDD = 5V, CIN = 1μF, COUT = 0.1μF, RL = 10Ω VIN = 0.8V, VDD = 2.5V, CIN = 1μF, COUT = 0.1μF, RL = 10Ω Time (50μs/Div) Time (50μs/Div) Turn-Off Response Time Turn-Off Response Time VOUT1 (2V/Div) EN1 (5V/Div) VOUT1 (5V/Div) EN1 (5V/Div) VOUT2 (2V/Div) EN2 (5V/Div) VOUT2 (5V/Div) EN2 (5V/Div) VIN = 2.5V, VDD = 2.5V, CIN = 1μF, COUT = 0.1μF, RL = 10Ω Time (50μs/Div) Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS9745A-00 August 2014 VIN = 5V, VDD = 5V, CIN = 1μF, COUT = 0.1μF, RL = 10Ω Time (50μs/Div) is a registered trademark of Richtek Technology Corporation. www.richtek.com 13 RT9745A Application Information The RT9745A is a small, low RON, dual channel load switch with EN controlled pins, and is equipped with a charge pump circuitry to drive the internal N-MOSFET switch. The product contains two N-channel MOSFETs that can operate between input voltage range of 0.8V to 5.5V. It also supports a maximum continuous current of 6A each channel and a maximum pulsed switch current of 8A (pulse <300μs). Each switch is independently controlled by EN pins (EN1 and EN2), which can directly interface with lowvoltage control signals. Output Filter Capacitor Input and Output Charge Pump VINx (input) is the power source connection to the internal circuitry and the Drain of the MOSFET. VOUTx (output) is the Source of the MOSFET. In a typical application, current flows through the switch from VINx to VOUTx toward the load. If VOUTx is greater than VINx, current will flow from VOUTx to VINx since the MOSFET is bidirectional when on. The switch has an internal charge pump circuit that is supplied from VDD pin to afford sufficient bias voltage to both N-Channel MOSFETs. The recommended VDD voltage range is 2.5V to 5.5V, and must above VIN for optimal low RON performance, or the value of RON will be greater than A 10 to 1 ratio of supply capacitor to output capacitor from VOUTx to GND is recommended to prevent the in-rush currents during low supply voltage start-up. Because the integrated body diode in the load switch, higher output capacitor can cause output voltage to exceed supply voltage when the system supply is removed. A output capacitor smaller then supply capacitor is recommended to prevent the current flow through the integrated body diode from output to system supply. the value listed in the ELECTRICAL CHARACTERISTICS table. On-Resistance Input Voltage Voltage On-Resistance vs. vs. Input (VIN Single Channel) Channel) (VIN >> VDD, Single Chip Enable Input Supply Filter/Bypass Capacitor A 1μF or greater low-ESR ceramic capacitor from VIN to GND, located at the device is strongly recommended to prevent the input voltage drooping during high current application. However, higher capacitor values will further reduce the voltage droop on the input. Furthermore, without the bypass capacitor, an output short may cause sufficient ringing on the input (from source lead inductance) to destroy the internal control circuitry. The input transient must not exceed 6V of the absolute maximum supply voltage even for a short duration. Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 14 100 90 On-Resistance (mΩ) The switch will be disabled when the ENx pin is in a logic low condition. During this condition, the internal circuitry and MOSFET will be turned off, reducing the supply current to 0.1μA typical. Floating the ENx may cause unpredictable operation. ENx should not be allowed to go negative with respect to GND. TA = 25°C, IOUT = −200mA 80 70 60 50 VDD VDD VDD VDD VDD VDD = = = = = = 2.5V 3.3V 3.6V 4.2V 5V 5.5V 40 30 20 0.8 1.2 1.6 2 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6 Input Voltage (V) Adjustable Rise Time The RT9745A provides an external adjustable rise time function. The adjustable rise time is used to prevent large inrush current and output voltage overshoot while the switch is being powered-up. The external capacitor connected from SS pins to GND is charged by a 1μA current source to set each rise time. is a registered trademark of Richtek Technology Corporation. DS9745A-00 August 2014 RT9745A Discharge Operation Thermal Considerations For continuous operation, do not exceed absolute maximum junction temperature. The maximum power dissipation depends on the thermal resistance of the IC package, PCB layout, rate of surrounding airflow, and difference between junction and ambient temperature. The maximum power dissipation can be calculated by the following formula : Maximum Power Dissipation (W)1 When ENx is low, the RT9745A will discharge the system residual voltage using internal MOSFET connected between the VOUTx and GND. The discharge current depends on the voltage at the VOUTx pin. When the voltage at the VOUTx is lower than 0.8V, the RT9745A will fully turn the internal MOSFET on to pull the VOUTx low. 3.5 Four-Layer PCB 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0 25 50 75 100 125 Ambient Temperature (°C) Figure 2. Derating Curve of Maximum Power Dissipation PD(MAX) = (TJ(MAX) − TA) / θJA where TJ(MAX) is the maximum junction temperature, TA is the ambient temperature, and θJA is the junction to ambient thermal resistance. For recommended operating condition specifications, the maximum junction temperature is 125°C. The junction to ambient thermal resistance, θJA, is layout dependent. For WDFN-14TL 3x2 package, the thermal resistance, θJA, is 32.1°C/W on a standard JEDEC 51-7 four-layer thermal test board. The maximum power dissipation at TA = 25°C can be calculated by the following formula : PD(MAX) = (125°C − 25°C) / (32.1°C/W) = 3.11W for WDFN-14TL 3x2 package The maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA. The derating curve in Figure 2 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS9745A-00 August 2014 is a registered trademark of Richtek Technology Corporation. www.richtek.com 15 RT9745A Outline Dimension 2 1 2 1 DETAIL A Pin #1 ID and Tie Bar Mark Options Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. Symbol Dimensions In Millimeters Dimensions In Inches Min. Max. Min. Max. A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.150 0.250 0.006 0.010 b1 0.550 0.650 0.022 0.026 D 2.900 3.100 0.114 0.122 D2 2.450 2.550 0.096 0.100 E 1.900 2.100 0.075 0.083 E2 0.850 0.950 0.033 0.037 e 0.400 0.016 K 0.200 0.008 K1 0.120 0.005 L 0.300 0.400 0.012 0.016 W-Type 14TL DFN 3x2 Package Richtek Technology Corporation 14F, No. 8, Tai Yuen 1st Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries. www.richtek.com 16 DS9745A-00 August 2014