RT9807 Micro-Power Voltage Detector with Manual Reset General Description Features The RT9807 is a micro-power voltage detector with deglitched manual reset input which supervises the power supply voltage level for microprocessors (μP) or digital systems. It provides internally fixed threshold levels ranging from 1.2V to 3.3V with 0.1V per step, which covers most digital applications. It features low supply current of 3μA. z Monitor System Voltages from 0.9V to 5.5V z Capacitor-Adjustable Reset Timeout Period Manual Reset Input Low Quiescent Current High Accuracy ±1.5% Low Functional Supply Voltage 0.9V N-Channel Open-Drain Output Small SOT-23-5 Package RoHS Compliant and Halogen Free The RT9807 performs supervisory function by sending out a reset signal whenever the VDD voltage falls below a preset threshold level. The timeout period of this reset signal can be adjusted via an external capacitor. Once VDD recovers above the threshold level, the reset signal will be released after a certain delay time. To manually pull reset signal low, just pull the manual reset input (MR) below the specified logic-low level. The RT9807 is available in an SOT-23-5 package. Ordering Information z z z z z z z Applications z z z z z Computers Controllers Intelligent Instruments Critical uP and uC Power Monitoring Portable/Battery-Powered Equipment Pin Configurations (TOP VIEW) RT9807Package Type B : SOT-23-5 VDD CT 5 4 Lead Plating System G : Green (Halogen Free and Pb Free) Output Voltage 12 : 1.2V 13 : 1.3V : 32 : 3.2V 33 : 3.3V Note : 2 RST GND MR SOT-23-5 Typical Application Circuit R 470k Richtek products are : `RoHS 3 compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. `Suitable for use in SnPb or Pb-free soldering processes. Marking Information VDD RT9807 5 1 VDD RST CIN 1uF 3 MR GND 2 CT 4 Reset CCT 10nF For marking information, contact our sales representative directly or through a Richtek distributor located in your area. DS9807-01 April 2011 www.richtek.com 1 RT9807 Functional Pin Description Pin No. Pin Name Pin Function 1 RST Reset Output Pin. (Open drain) 2 GND Ground Pin. 3 MR Manual Reset Pin. 4 CT Connect an external capacitor for setting reset timeout period. 5 VDD Supply Voltage Input Pin. Function Block Diagram N-MOSFET - VDD + Comparator VREF Timeout Setting GND Manual Reset MR Absolute Maximum Ratings z z z z z z z z z z CT (Note 1) Supply Input Voltage, VDD ----------------------------------------------------------------------------------------------Reset Output Voltage, RST --------------------------------------------------------------------------------------------Other Pins ------------------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C SOT-23-5 -------------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) SOT-23-5, θJA --------------------------------------------------------------------------------------------------------------Junction Temperature Range -------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Mode) ---------------------------------------------------------------------------------------------MM (Machine Mode) ------------------------------------------------------------------------------------------------------ Recommended Operating Conditions z RST −0.3V to 6V −0.3V to 6V −0.3V to 6V 0.4W 250°C/W 150°C 260°C −65°C to 150°C 2kV 200V (Note 4) Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 85°C www.richtek.com 2 DS9807-01 April 2011 RT9807 Electrical Characteristics (TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit 0.9 -- 5.5 V -- 3 5 μA Operating VDD Range VDD Supply Current IDD Reset Threshold VTH 1.2 -- 3.3 V Threshold Voltage Accuracy ΔVTH −1.5 -- 1.5 % Threshold Voltage Hysteresis VHYS -- 50 x VTH -- mV -- 100 -- ppm/°C VTH = 3V, VDD = 4.5V Reset Threshold Tempco VDD Drop to Reset Delay tRP Drop = VTH – 250mV -- 100 -- μs RST Output Voltage Low (Note 5) VOL VDD < VTH(min.), ISINK = 3.5mA -- -- 0.4 V VIH 0.7VDD -- -- VIL -- -- 0.25VDD MR Glitch Rejection -- 80 -- ns MR to Reset Propagation Delay tMR -- 2 -- μs MR Pull-up Resistance RMR -- 20 -- kΩ Reset Timeout Period tRP 3.35 4.375 5.40 -- 0.275 -- CT Source Current IRAMP -- 240 -- CT Source Threshold Voltage VTH-RAMP -- 0.65 -- V -- 33 -- mV Logic-High MR Input Threshold voltage Logic-Low CCT = 1500pF CCT = 0pF CT Threshold Hysteresis V ms nA 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 natural convection at TA = 25°C on a low effective thermal conductivity 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. Note 5. The voltage VOL can be calculated by VOL = VDD - Ir x R. Where R is the pull-up resistor and Ir is the current flowing through the pull-up resistor. For typical application R = 100kΩ, VOL is less than 0.2V. DS9807-01 April 2011 www.richtek.com 3 RT9807 Typical Operating Characteristics Supply Current vs. Input Voltage CT Threshold Voltage vs. Temperature 6 Supply Current (μA) 5 TA = 125°C TA = 85°C TA = 25°C 4 3 TA = −40°C 2 1 CT Threshold Voltage (V) 0.67 0.66 Rising 0.65 0.64 0.63 Falling 0.62 0.61 CT Open 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 R = 470kΩ 0.6 5.5 -50 -25 0 150 100 10 1 VDD = 5V, R = 470kΩ 0.1 1 10 100 VDD Drop Reset Delay Time (μs) Reset Delay Time (ms) 1000 0.01 75 100 125 VDD = 5V, CT Open, R = 470kΩ 130 110 90 70 50 1000 -50 -25 0 Capacitance (nF) 25 50 75 100 125 Temperature (°C) Power On Reset Delay Time vs. Temperature Detector Threshold vs. Temperature 1.7 350 1.65 Rising 1.6 Falling 1.55 1.5 1.45 VDD = 5V, CT Open, R = 470kΩ 1.4 -50 -25 0 25 50 Temperature (°C) www.richtek.com 4 75 100 125 Power On Reset Delay Time (μs) Detector Threshold (V) 50 VDD Drop Reset Delay Time vs. Temperature Reset Delay Time vs Capacitance 10000 0.1 0.001 25 Temperature (°C) Input Voltage (V) 300 250 200 150 VDD = 5V, CT Open, R = 470kΩ 100 -50 -25 0 25 50 75 100 125 Temperature (°C) DS9807-01 April 2011 RT9807 Application Information The RT9807 provides adjustable reset delay time to fit the need of a variety of μP applications. The reset delay time of the RT9807 can be adjusted by connecting a capacitor between the CT pin and GND. The CT capacitor must fit the need of low-leakage (<10nA), and it is recommended to use a ceramic capacitor such as X7R or NPO type. VCC 0.18 x 106 x CCT (μF) VDD RST GND CT R1 CCT Figure 2. Voltage Divider When the VDD voltage exceeds the VDD threshold voltage, a current source will start to charge the CT capacitor and the CT voltage will rise. When the CT voltage exceeds 0.65V, the RST voltage will change from low to high. Therefore, there is a delay time between the point of VDD reaching its threshold voltage and the RST active-high point. The delay time can be calculated according to the following equation. 0.58 RT9807 R1 Reset Delay Time Setting tDELAY (μ s) = R The rising and falling of the VCC and RST voltage can be explained in five steps as shown in the following diagram. 1 2 3 4 5 B VCC A Hysteresis range + 220 VCC_TH VCC_TH – Hysteresis Voltage Minimum Operation Voltage GND VDD Threshold Voltage VDD Voltage GND RST Voltage 0.65V Power-On Reset Delay Time VCT GND GND Drop Reset Delay Time RST Voltage Figure 3. Operation Diagram GND 1. RST voltage is pulled up to VCC voltage. Delay Time Figure 1. Delay Time Operating with a Voltage Divider The voltage detector monitors the VCC voltage to generate a reset signal when VCC is higher than the detecting level. The detecting level is determined by an external resistive voltage divider. R1 ⎞ ⎛ VCC_TH = VTH x ⎜ 1 + , VTH : Threshold Voltage. R2 ⎟⎠ ⎝ R1 ⎞ ⎛ VCC_HYS = VHYS x ⎜ 1 + ⎟ R2 ⎝ ⎠ DS9807-01 April 2011 2. When the VCC voltage is down to the detector threshold voltage (Point A), RST voltage becomes low level. 3. When the VCC voltage is lower than minimum operating voltage, the RST voltage is indefinite. In the case of open drain type, RST voltage is equal to pull-up voltage. 4. RST voltage becomes low level. 5. When the VCC voltage exceeds the threshold voltage (Point B), the internal source current will start to charge CT capacitor. The RST voltage will go high after a delay time when the CT capacitor voltage reaches 0.65V. www.richtek.com 5 RT9807 Interfacing to Other Voltages TA = 25°C can be calculated by the following formula : The RT9807 is an open-drain voltage detector that can provide different voltage level of reset signals for processor application. As shown in Figure 4, the open-drain output can be connected to another voltage level less than 5.5V. This allows for easy logic compatibility to various microprocessors. P D(MAX) = (125°C − 25°C) / (250°C/W) = 0.4W for SOT-23-5 package 5V 0.50 470k RT9807 RST RST VDD 3.3V 1µF GND Figure 4 Manual Reset Input Many processor based products require manual reset capability, allowing the user or external logic circuitry to initiate a reset. A logic low on MR asserts reset. Reset remains asserted while MR is low and for the reset timeout period after MR returns high. Connect a normally open momentary switch from MR to ground to create a manual reset function. 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 : Maximum Power Dissipation (W) 5V System The maximum power dissipation depends on operating ambient temperature for fixed T J(MAX) and thermal resistance θJA. For RT9807 package, the derating curve in Figure 5 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. Single Layer PCB 0.45 0.40 0.35 0.30 0.25 0.20 SOT-23-5 0.15 0.10 0.05 0.00 0 25 50 125 Layout Considerations CT is a precise current source. When developing the layout for the application, be careful to minimize board capacitance and leakage currents around this pin. Traces connected to CT should be kept as short as possible. Traces carrying high-speed digital signals and traces with large voltage potentials should be routed as far from CT as possible. Leakage current and stray capacitance (e.g., a scope probe) at this pin can cause errors in the reset delay time. R 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. www.richtek.com 6 100 Figure 5. Derating Curve for RT9807 Package PD(MAX) = ( TJ(MAX) − TA ) / θJA For recommended operating conditions specification of the RT9807, the maximum junction temperature is 125°C. The junction to ambient thermal resistance θJA is layout dependent. For SOT-23-5 package, the thermal resistance θJA is 250°C/W on the standard JEDEC 51-3 single layer thermal test board. The maximum power dissipation at 75 Ambient Temperature (°C) RST 1 GND 2 MR 3 5 VDD CIN SW GND CCT 4 CT CCT should be placed as close as possible to the IC. Figure 6. PCB Layout Guide DS9807-01 April 2011 RT9807 Outline Dimension H D L B C b A A1 e Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 0.889 1.295 0.035 0.051 A1 0.000 0.152 0.000 0.006 B 1.397 1.803 0.055 0.071 b 0.356 0.559 0.014 0.022 C 2.591 2.997 0.102 0.118 D 2.692 3.099 0.106 0.122 e 0.838 1.041 0.033 0.041 H 0.080 0.254 0.003 0.010 L 0.300 0.610 0.012 0.024 SOT-23-5 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. DS9807-01 April 2011 www.richtek.com 7