TSM101/A VOLTAGE AND CURRENT CONTROLLER . . . .. 1.24V SERIES VOLTAGE REFERENCE WITH 10mA OUTPUT CURRENT AND 1% PRECISION (TSM101A) TWO OPERATIONAL AMPLIFIERS WITH ORED OUTPUT AND 1MHZ GAIN BANDWIDTH PRODUCT BUILT-IN CURRENT GENERATOR WITH ENABLE/DISABLE FUNCTION 4.5 TO 32V SUPPLY VOLTAGE RANGE SO8, DIP8 AND TSSOP8 PACKAGES N DIP8 (Plastic Package) D SO8 (Plastic Micropackage) P TSSOP8 (Thin Shrink Small Outline Package) ORDER CODES DESCRIPTION The TSM101/TSM101Aintegrated circuit incorporates a high stability series band gap voltage reference, two ORed operational amplifiers and a current source. This IC compares the DC voltage and the current level at the output of a switching power supply to an internal reference. It provides a feedback through an optocoupler to the PWM controller IC in the primary side. The controlled current generator can be used to modify the level of current limitation by offsetting the information coming from the current sensing resistor. APPLICATIONS This circuit is designed to be used in battery chargers with a constant voltage and a limited output current. It can be used in every types of applicationrequiring a precision voltage regulation and current limitation. Other applications include voltage supervisors, over voltage protection... June 1999 Part Number TSM101C/AC TSM101I/AI Package Temperature Range N D P -20, +80oC • • • • • • o -40, +105 C PIN CONNECTIONS 1 Vref 8 2 7 3 6 4 5 1/15 TSM101/A ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit VCC DC Supply Voltage - (note 1) 36 V Iout Output Current - (note 2) 20 mA Pd Power Dissipation 200 mW Vin Input Voltage - (note 3) Iin Input Current Tstg Tj Tthja -0.3, VCC -1.5 V ±1 mA Storage Temperature Maximum Junction Temperature Thermal Resistante Junction to Ambiant -40 to +125 o C 150 o C o 130 to 200 C/W Notes : 1. All voltages values, except differential voltage are with respect to network ground terminal 2. The voltage reference is not protected against permanent short circuit OPERATING CONDITIONS Symbol TSM101C/AC/I/AI Parameter VCC Supply Voltage Toper Operating Free Air Temperature Range Value 4.5 to 32 Unit V o Tmin. to Tmax. C ELECTRICAL CHARACTERISTICS Tamb = 25oC, VCC = 15V (unless otherwise specified) OPERATIONAL AMPLIFIER : TSM101C/I/AC/AI Symbol Parameter ICC Total Supply Current Vi Input Voltage Range Vio Input Offset Voltage Iib Input Bias Current @ Vin = 1.2V on pin 7 and Vin = 0V on pin 5 Isink Avo Output Sink Current, Vol = 2.5V Large Signal Voltage Gain Test Conditions Min. Typ. VCC = 15V 0 Max. Unit 2 mA VCC -1.5V V 25oC Tmin. <T amb.<Tmax. -5 -7 1 5 7 mV o -700 -1000 -300 0 0 25 C Tmin. <T amb.<Tmax. nA o 15 25 C Tmin. <T amb.<Tmax. 8 RL = 2kΩ Tmin. <T amb.<Tmax. 15 Tmin. <T amb.<Tmax. 65 mA V/mV SVR Supply Voltage Rejection Ratio CMR Common Mode Rejection Ratio Tmin. <T amb.<Tmax. 80 dB GBP Gain Bandwidth Product VCC = 15V, F = 100kHz Vin = 10mV, RL = 2kΩ CL = 100pF 1 MHz Ioh Output Leakage Current 25 C Tmin. <T amb.<Tmax. 2/15 o 90 dB 2 7 µA TSM101/A ELECTRICAL CHARACTERISTICS Tamb = 25oC, VCC = 15V (unless otherwise specified) VOLTAGE REFERENCE : TSM101 Symbol Parameter Vref Reference Voltage Kvt Temperature Stability TSM101C Test Conditions Iout = 1mA, Tamb. = 25oC TSM101I Unit Min. Typ. Max. Min. Typ. Max. 1.21 1.24 1.27 1.21 1.24 1.27 V 30 100 35 120 ppm/ C Tmin. <T amb.<Tmax. o Reglo Load Regulation 1 < Iout < 10mA 5 15 5 15 mV R egli Line Regulation 5 < Vin < 32V 3.5 10 3.5 10 mV VOLTAGE REFERENCE : TSM101A Symbol Parameter Vref Reference Voltage Kvt Temperature Stability TSM101AC Test Conditions o Iout = 1mA, Tamb. = 25 C TSM101AI Unit Min. Typ. Max. Min. Typ. Max. 1.227 1.24 1.252 1.227 1.24 1.252 V 30 100 35 120 ppm/ C Tmin. <T amb.<Tmax. o Reglo Load Regulation 1 < Iout < 10mA 5 15 5 15 mV R egli Line Regulation 5 < Vin < 32V 3.5 10 3.5 10 mV CURRENT GENERATOR : TSM101, TSM101A Symbol Parameter Test Conditions TSM101C/AC Min. TSM101I/AI Max. Min. Typ. Max. Unit 1.4 1.4 mA Kcgt Temperature Stability Tmin. <T amb.<Tmax. 500 600 ppm/ oC C glir Line Regulation 4.5 < VCC < 32V 0.003 Vcsen Voltage at the enable pin to have IO = 1.4mA Tmin. <T amb.<Tmax. Vcsdis Voltage at the enable pin to have IO = 0mA Tmin. <T amb.<Tmax. Icsen Input Current on the C sen pin Tmin. <T amb.<Tmax. Icsleak Leakage Current Vcs = 2V Tmin. <T amb.<Tmax. Io Current Source Typ. 0.03 0.003 0.6 2 0.03 mA 0.6 V 2 V 30 0.5 2 30 0.5 2 µA µA 3/15 TSM101/A 8 Vre f Gnd 1 +Vcc Vre f 4 7 Vrin Cs e n Crre f Crin 6 2 OUTP UT 3 5 DESCRIPTION 4/15 Name Pin Type Vref 1 OUTPUT Function Voltage Reference Output 1.24V, 10mA max. Do not short circuit Vrin 7 INPUT Voltage Regulation Loop Input C rin 5 INPUT Current Limitation Loop Input, connected to the sense resistor Crref 3 INPUT Current Limitation Reference Input C sen 2 INPUT Current source enable input. This current source can be used to offset the voltage measurement on the sense resistor and therefore to modify the charge current. The current source is enabled when the input voltage on pin 2 is lower than 0.8V. OUTPUT 6 OUTPUT Output pin common to the voltage regulation and current limitation loops. This output can drive the primary side (LED) of an optocoupler. VCC 8 INPUT Power Supply Input (4.5 to 32VDC) GND 4 INPUT Ground TSM101/A APPLICATION NOTE A BATTERY CHARGER USING THE TSM101 by S. LAFFONT and R. LIOU This technical note shows how to use the TSM101 integrated circuit with a switching mode power supply (SMPS) to realize a battery charger. An example of realization of a 12V Nickel-cadmium battery charger is given. 1 - TSM101 PRESENTATION The TSM101 integrated circuit incorporates a high stability series band gap voltage reference, two ORed operational amplifiers and a current source (Figure 1) Figure 1 : TSM101 Schematic Diagram 1 Vref A great majority of low or medium end power supplies is voltage regulated by using shunt programmable voltage references like the TL431 (Figure 2). The galvanic insulation of the control information is done by using an opto-coupler in linear mode with a variable photo current depending on the difference between the actual output voltage and the desired one. A current limitation is used to protect the power supply against short circuits, but lacks precision. This limitation is generally realized by sensing the current of the power transistor, in the primary side of the SMPS. The role of the TSM101 is to make a fine regulation of the output current of the SMPS and a precise voltage limitation. The primary current limitation is conserved and acts as a security for a fail-safe operation if a short-circuit occurs at the output of the charger. 8 2 7 3 6 4 5 This IC compares the DC voltage and the current level at the output of a switching power supply to an internal reference.It provides a feedback through an optocoupler to the PWM controller IC in the primary side. The controlled current generator can be used to modify the level of current limitation by offsetting the information coming from the current sensing resistor. 2 - PRINCIPLE OF OPERATION The current regulation loop and the voltage limitation loop use an internal 1.24V band-gap voltage reference. This voltage reference has a good precision (better than 1.5%) and exhibits a very stable temperature behavior. The current limitation is performed by sensing the voltage across the low ohmic value resistor R5 and comparing it to a fixed value set by the bridge composed by R2 and R3 (Figure 3). When the voltage on R5 is higher than the voltage on R3 the output of the current loop operational amplifier decreases. The optocoupler current increases and tends to reduce the output voltage by the way of the PWM controller. The voltage regulation is done by comparing a part of the output voltage (resistor bridge R6, R7 and P1) to the voltage reference (1.24V). If this part is higher than 1.24V, the output of the voltage loop operational amplifier decreases. 5/15 TSM101/A Figure 2 : SMPS Using a TL431 as Voltage Controller The optocoupler current increases and tends to reduce the output voltage by the way of the PWM controller. By enabling the TSM101 current source (pin 2) it is possible to offset the current sensing by a voltage equal to : ence of this diode on the charge is negligible if the voltage drop (0.7V) is taken into account during the design of the charger. The voltage at the output of the charger is : R6+R7 xVr R6 and regarding R6 and R7 : • Vout = • Voff # R4 * Io with Io = 1.4mA This offset lowers the output charge current and this function can be used to charge two types of batteries having different capacities. The current source is enabled by connecting pin 2 to ground • R6 = ( 3 - CALCULATION OF THE ELEMENTS The charge current is regulated at 700mA (if the charge control input is left open) or 200mA (if the charge control input is put to ground ), allowing the charge of two different types of batteries. • R7 = 12kΩ 3.1 - Voltage limitation The end-of- charge voltage is limited at 1.45V/cell, this is the recommended voltage for an ambient temperature at 25oC. A diode is generally inserted at the output of the charger to avoid the discharge of the battery if the charger is not powered. This diode is sometimes directly integrated in the battery pack. The influ6/15 Vref ) x R7 Vout − Vref P1, which is a part of R6 and R7 is not considered in this equation. The following values are used on the application board : • R6 = 1kΩ • P1 = 220Ω, adjust for Voutput = 15.2V with the battery replaced by a 1kΩ resistor • R10 = short circuit • C3 = 100nF 3.2 - Current regulation R5 is the sense resistor used for current measurement. TSM101/A The current regulation is effective when the voltage drop across R5 is equal to the voltage on pin 5 of the TSM101 (assuming that the internal current source is disabled). For medium currents (<1A), a voltage drop across R5 of 200mV = Vr5 is a good value, R5 can be realized with standard low cost 0.5W resistors in parallel. Vr5 , R5 = 0.285Ω (four 1.2Ω resistor in Ich parallel) R2 and R3 can be chosen using the following formula : • R5 = • R2 = R3 x (Vref − Vr5) Vr5 CHARGE CONTROL If the pin 2 is left open, the charge current is nominal at # 700mA. If pin 2 is connected to ground, the internal current source is enabled, the current measurement is off-setted by a voltage equal to : • Vr4 = Io x R4 with Io = 1.4mA This can be used to lower the charging current or eventually to stop the charge, if Vr4 > Vr5 In our example, the current offset is equal to 700 200mA = 500mA, representing a voltage offset Vr4 = 140mV across R4. The following values are used on the application board : • R5 = 4 *1.2Ω 0.5W in parallel • R4 = 100Ω • R2 = 1.2kΩ • R3 = 220Ω • R9 = short circuit • R1 = 10kΩ • C2 = 100nF • C5 = 100nF • C1 = output capacitor of the SMPS • C4 = 10µF 4 - SCHEMATIC DIAGRAM Figure 2 represents a schematic of the output circuit of a ”classical” SMPS using a TL431 for voltage regulation. This circuit is modified to use the TSM101 and the final circuit is represented in figure 3. Figure 3 : SMPS Using the TSM101 7/15 TSM101/A 5 - IMPROVEMENT 5.2. Power supply for TSM101 5.1. High frequency compensation In applications requiring low voltage battery charge or when the charger is in current regulation mode, the outputvoltage can be too low to supply correctly the TSM101. The same problem occurs when the output is shortcircuited. A solution to provide a quasi constant supply voltage to the TSM101 is shown at figure 4 : an auxiliary Two R-C devices (R9 + C2 & R10 + C3) are used to stabilize the regulation at high frequencies. The calculation of these values is not easy and is a function of the transfer function of the SMPS. A guess value for the capacitors C2 and C3 is 100nF. Figure 4 : An Auxiliary Winding for TSM101 Power Supply winding is added at the secondary side of the transformer. This winding is forward coupled to the primary winding, the voltage across it is directly proportional to the mains rectified voltage, even if the flyback voltage is close to zero. As this auxiliary winding is a voltage source, it is necessary to add a resistor (R11) on the cathode of the rectifier (D3) to limit the current. 8/15 A low cost regulator (Q2 and Zener diode D4) is used to power the TSM101. This is necessary with autoranging SMPS with wide input voltages, for example 90 to 240V without switching. In standard SMPS with voltage range from 200 to 240VAC or 100 to 130VAC, this regulator can be removed and replaced by the small power supply shown on figure 5 (Raux, Caux, D2). TSM101/A 5.3. Higher Precision for the Voltage Control The voltage drop through the sense resistor R5 offsets the voltage measurement. In most battery charging applications, this offset is not taken into account because the error is negligeable compared to the end-of-charge voltage due to the fact that the charging current value decreases drastically during the final phase of the battery charging. But in other applications needing highest possible precision in voltage control, another connecting schematic is possible for TSM101 as shown on figure 5. In this schematic, the 0V reference is defined as the common point between the sense resistor, the 0V Output Voltage, the foot of the resistor bridge R6/R7, and the ground (pin 4) of the TSM101. TSM101A(1% internal voltage referenceprecision) is required in such applications. Figure 5 : Precise Output Voltage Control 5.4. An example of application where the charging current is different according to the charging phase. The following application includes a specific recommendation which requires that the charging current should be fixed to Ich1 = 800mAin normal charging conditions, and Ich2 = 200mA when the cell voltage is below Vl=2.5V to optimize the cell life-time. Moreover, an Charging Status LED should be switched off when the cell voltage is above Vh=6.5V. Figure 6 shows how this can easily be achieved using an additional dual comparator (type LM393) where the first operator (C1) is used to activate the TSM101 internal current generator to offset the current measurement thanks to R4, and the second (C2) is used to switch the status LED off. On figure 6, the status signal is determined by voltage measurement, this could as well be achieved by current measurement. If V5 = 100mV is the maximum tolerable voltage drop through the sense resistor R5 during normal 9/15 TSM101/A charging conditions, then the following calculations apply : Current Control : R5 = V5 / Ich1 = 0.1 / 0.8 = 0.125 R5 = 125mΩ V5 = Vref x R3 / (R2 + R3) with R2 + R3 ~ 12kΩ and Vref = 1.24V R3 = 1kΩ, R2 = 11.4kΩ V5 = R4 x Io + R5 x Ich2, therefore, R4 = (V5 - R5 x Ich2) / Io with Io = 1.4mA Figure 6 : Optimized Charging Conditions 10/15 R4 = 53.6Ω Vref = Vl x R15 / (R14 + R15) with Vl = 2.5V and R14 + R15 ~ 20kΩ R15 = R14 = 10kΩ Voltage Control : Vref = Vh x R6 / (R6 + R7) with Vh = 6.5V and R6 + R7 ~ 12kΩ R6 = 2.36kΩ, R7 = 10kΩ Vref = Vh R17 / (R16 + R17) R17 = 10kΩ, R16 = 42kΩ TSM101/A EVALUATION BOARD - TECHNICAL NOTE TSM101 integrates in the same 8 pin DIP or SO package • one 1.24V precision voltage reference • two operationnal amplifiers • two diodes which impose a NOR function on the outputs of the operationnal amplifiers • one current source which can be activated/ inhibited thanks to an external pin. An immediate way to take advantage of the high integration and reliability of TSM101 is to use it as a voltage and current controller on power supplies secondary. The application note AN896 describes precisely how to use TSM101 in an SMPS battery charger. The TSM101 Evaluation Board is adaptable to any power supply or battery charger (SMPS or linear) as a voltage and current controller with minimal constraints from the user. HOW TO USE THE TSM101 EVALUATION BOARD ? The generic Electrical Schematic is shown on figure 1. It represents an incomplete SMPS power supply where the primary side is simplified. The ”IN+”and ”IN-” power inputs of the evaluation board should be connected directly to the power lines of the power supply secondary. The ”Vcc” input of the evaluation board should be connected to the auxiliary supply line. In the case of an SMPS power supply, the ”Reg” output of the evaluation board should be connected to the Optocoupler input to regulate the PWM block in the primary side. In the case of a linear power supply, the ”Reg” output should be connected to the base of the darlington to regulate the power output. A diode might be needed on the output of the evaluation board in the case of a battery charger application to avoid the discharge of the battery when the charger is not connected. COMPONENTS CALCULATIONS The voltage control is given by the choice of the resistor bridge R6/R7 (and the trimmer P1) due to equation 1 : • Vref = R6/(R6+R7)xVout where Vref = 1.24V eq1 Figure 1 11/15 TSM101/A The current control is given by the choice of the voltage drop through the sense resistor R5 (to be linked to the nominal current of the application) and by the value of the sense resistor itself. For medium currents (< 1A), a good value for the voltage drop through R5 can be Vsense = 200mV (dissipation < 200mW). The resistor bridge R2/R3 should be chosenfollowing equation 2 : • Vsense = R3/(R2+R3)xVref eq2 The total value of the resistor bridge should be in the range of the kΩ in order to ensure a proper charge for the voltage reference(in the range of the mA). To set the current limit, the sense resistor R5 should be chosen following equation 3 : • Ilim = Vsense/R5 eq3 The internal current generator (Isce) can be used to offset the current limitation with a lower value. This current generator is activated by connecting pin 2 to ground. It is inhibited if pin 2 is connected to the positive rail via the pull up resistor R1. The current offset is given by the choice of the resistor R4. If Ilim1 is the current limit calculated in the previous paragraph, and Ilim2 is the current limit that is to be set when pin 2 is connected to ground, R4 should be chosen following equation 4 : • R4 = (Vsense - Ilim2xR5)/Isce eq4 where Isce = 1.4mA C4 and C5 are bypass capacitors used to smoothen the regulated outputs. C2 and C3 are capacitors used for high frequency compensation. EXAMPLES OF COMPONENT LISTS Table 1 summerizes a few examples of component lists to generate quickly 15V/700mA/20 0mA, 12V/1A/500mAor 8.2V/200mA/100mAvoltage and current regulations. 12/15 Table 1 Voltage / Current Control 15V 700mA 200mA 12V 1A 500mA 8.2V 200mA 100mA R1 10kΩ 10kΩ 10kΩ R2 1.2kΩ 1.2kΩ 1.2kΩ R3 220Ω 220Ω 220Ω R4 100Ω 68Ω 68Ω 1Ωx1 R5 1.2Ωx4 0.8Ωx4 R6 1kΩ 1kΩ 1kΩ R7 12kΩ 8.2kΩ 5.6kΩ P1 100Ω 100Ω 100Ω 0Ω 0Ω 0Ω C2 100nF 100nF 100nF C3 100nF 100nF 100nF C4 10µF 22µF 4.7µF C5 100nF 100nF 100nF 2 straps Figure 2 represents in real dimensions thePCB and the silkscreen of the TSM101 Evaluation board. Figure 2 TSM101/A PACKAGE MECHANICAL DATA 8 PINS - PLASTIC DIP Dim. A a1 B b b1 D E e e3 e4 F i L Z Min. Millimeters Typ. 3.32 0.51 1.15 0.356 0.204 Max. 1.65 0.55 0.304 10.92 9.75 7.95 Min. 0.020 0.045 0.014 0.008 Max. 0.065 0.022 0.012 0.430 0.384 0.313 2.54 7.62 7.62 3.18 Inches Typ. 0.131 0.100 0.300 0.300 6.6 5.08 3.81 1.52 0.125 0260 0.200 0.150 0.060 13/15 TSM101/A PACKAGE MECHANICAL DATA 8 PINS - PLASTIC MICROPACKAGE (SO) Dim. A a1 a2 a3 b b1 C c1 D E e e3 F L M S 14/15 Min. Millimeters Typ. 0.1 0.65 0.35 0.19 0.25 Max. 1.75 0.25 1.65 0.85 0.48 0.25 0.5 Min. Inches Typ. 0.026 0.014 0.007 0.010 Max. 0.069 0.010 0.065 0.033 0.019 0.010 0.020 0.189 0.228 0.197 0.244 0.004 o 45 (typ.) 4.8 5.8 5.0 6.2 1.27 3.81 3.8 0.4 0.050 0.150 4.0 1.27 0.6 0.150 0.016 o 8 (max.) 0.157 0.050 0.024 TSM101/A PACKAGE MECHANICAL DATA 8 PINS -THIN SHRINK SMALL OUTLINE PACKAGE Dim. Millimeters Min. Typ. A Min. Typ. 1.20 A1 0.05 A2 0.80 b c D 2.90 Max. 0.05 0.15 0.01 1.05 0.031 0.19 0.30 0.007 0.15 0.09 0.20 0.003 0.012 3.10 0.114 4.50 0.169 8o 0o 0.75 0.09 E E1 Inches Max. 1.00 3.00 6.40 4.30 e 4.40 0o l 0.50 0.60 0.039 0.118 0.041 0.122 0.252 0.65 k 0.006 0.173 0.177 0.025 8o 0.0236 0.030 Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement 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 STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publ ication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. 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