TSM1051

TSM1051 CONSTANT VOLTAGE AND CONSTANT CURRENT CONTROLLER FOR BATTERY CHARGERS AND ADAPTORS s CONSTANT VOLTAGE AND CONSTANT s s s s s s CURRENT CONTROL LOW VOLTAGE OPERATION PRECISION INTERNAL VOLTAGE REFERENCE LOW EXTERNAL COMPONENT COUNT CURRENT SINK OUTPUT STAGE EASY COMPENSATION LOW AC MAINS VOLTAGE REJECTION ORDER CODE Part Number TSM1051CLT TSM1051CD Temperature Range 0 to 85°C 0 to 85°C Package Marking L • • D M801 M1051C L = Tiny Package (SOT23-6) - only available in Tape & Reel (LT) D = Small Outline Package (SO) - also available in Tape & Reel (DT) DESCRIPTION TSM1051 is a highly integrated solution for SMPS applications requiring CV (constant voltage) and CC (constant current) mode. TSM1051 integrates one voltage reference, two operational amplifiers (with ORed outputs common collectors), and a current sensing circuit. The voltage reference combined with one operational amplifier makes it an ideal voltage controller, and the other low voltage reference combined with the other operational amplifier makes it an ideal current limiter for output low side current sensing. The current threshold is fixed, and precise. The only external components are: * a resistor bridge to be connected to the output of the power supply (adapter, battery charger) to set the voltage regulation by dividing the desired output voltage to match the internal voltage reference value. * a sense resistor having a value and allowable dissipation power which need to be chosen according to the internal voltage threshold. * optional compensation components (R and C). TSM1051, housed in one of the smallest package available, is ideal for space shrinked applications such as adapters and battery chargers. APPLICATIONS L SOT23-6 (Plastic Package) D SO8 (Plastic Micro package) PIN CONNECTIONS (top view) SOT23-6 1 2 3 Vctrl Gnd Out Vcc Vsense Ictrl 6 5 4 1 2 3 4 Vctrl Vcc SO8 Gnd Out Ictrl Nc 8 7 6 5 Vsense Nc s ADAPTERS s BATTERY CHARGERS January 2002 1/9 TSM1051 PIN DESCRIPTION SOT23-6 Pinout Name Vcc Gnd Vctrl Ictrl Out Vsense Pin # 6 2 1 4 3 5 Type Power Supply Power Supply Analog Input Analog Input Current Sink Output Analog Input Function Positive Power Supply Line Ground Line. 0V Reference For All Voltages Input Pin of the Voltage Control Loop Input Pin of the Current Control Loop Output Pin. Sinking Current Only Input Pin of the Current Control Loop SO8 Pinout Name Vcc Gnd Vctrl Ictrl Out Vsense NC NC Pin # 2 8 1 6 7 3 5 4 Type Power Supply Power Supply Analog Input Analog Input Current Sink Output Analog Input Function Positive Power Supply Line Ground Line. 0V Reference For All Voltages Input Pin of the Voltage Control Loop Input Pin of the Current Control Loop Output Pin. Sinking Current Only Input Pin of the Current Control Loop ABSOLUTE MAXIMUM RATINGS Symbol Vcc Vi Top Tj Rthja Rthja DC Supply Voltage DC Supply Voltage Input Voltage Operating Free Air Temperature Range Maximum Junction Temperature Thermal Resistance Junction to Ambient SO8 package Thermal Resistance Junction to Ambient SOT23-6 package Value 14 -0.3 to Vcc 0 to 85 150 130 250 Unit V V °C °C °C/W °C/W 2/9 TSM1051 OPERATING CONDITIONS Symbol Vcc DC Supply Conditions Parameter Value 2.5 to 12 Unit V ELECTRICAL CHARACTERISTICS Tamb = 25°C and Vcc = +5V (unless otherwise specified) Symbol Parameter Test Condition Min Typ Max Unit Total Current Consumption Icc Total Supply Current - not taking the output sinking current into account Tamb 0 < Tamb < 85°C 1.1 1.2 2 mA Voltage Control Loop Gmv Vref Iibv Transconduction Gain (Vctrl). Sink Current Only 1) Voltage Control Loop Reference 2) Input Bias Current (Vctrl) Tamb 0 < Tamb < 85°C Tamb 0 < Tamb < 85°C Tamb 0 < Tamb < 85°C 1 1.198 1.186 3.5 2.5 1.21 50 100 1.222 1.234 mA/mV V nA Current Control Loop Gmi Vsense Iibi Transconduction Gain (Ictrl). Sink Current Only 3) Current Control Loop Reference 4) Current out of pin ICTRL at -200mV Tamb 0 < Tamb < 85°C Iout = 2.5mA Tamb 0 < Tamb < 85°C Tamb 0 < Tamb < 85°C 1.5 196 192 7 200 25 50 204 208 mA/mV mV µA Output Stage Vol Ios Low output voltage at 10 mA sinking current Output Short Circuit Current. Output to Vcc. Sink Current Only Tamb 0 < Tamb < 85°C Tamb 0 < Tamb < 85°C 200 27 35 50 mA mV 1. If the voltage on VCTRL (the negative input of the amplifier) is higher than the positive amplifier input (Vref=1.210V), and it is increased by 1mV, the sinking current at the output OUT will be increased by 3.5mA. 2. The internal Voltage Reference is set at 1.210V (bandgap reference). The voltage control loop precision takes into account the cumulative effects of the internal voltage reference deviation as well as the input offset voltage of the trans-conductance operational amplifier. The internal Voltage Reference is fixed by bandgap, and trimmed to 0.5% accuracy at room temperature. 3. When the positive input at ICTRL is lower than -200mV, and the voltage is decreased by 1mV, the sinking current at the output OUT will be increased by 7mA. 4. The internal current sense threshold is set to -200mV. The current control loop precision takes into account the cumulative effects of the internal voltage reference deviation as well as the input offset voltage of the trans-conduction operational amplifier. 3/9 TSM1051 Figure 1 : Internal Schematic Vcc 1.210V + + - Out 200mV Gnd Ictrl Vsense Figure 2 : Typical Adapter or Battery Charger Application Using TSM1051 D OUT+ R2 TSM1051 Vcc 1.210V Out Rout To primary + Cvc2 22pF Rvc1 470K Cvc1 IL 2.2nF 200mV + Gnd Cic1 2.2nF Ric1 22K + R1 + Ictrl Vsense Ric2 500 Vsense Rsense IL In the above application schematic, the TSM1051 is used on the secondary side of a flyback adapter (or battery charger) to provide an accurate control of voltage and current. The above feedback loop is made with an optocoupler. 4/9 Load OUT- TSM1051 Figure 3 : Vref vs Ambient Temperature 1,230 1,225 2,5V ≤ Vcc ≤ 12V Vsense (V) Figure 6 : Vsense vs Ambient Temperature 203,5 203,0 202,5 Vcc=2,5V 202,0 201,5 201,0 200,5 Vcc=12V Vcc=5V 1,220 Vref (V) 1,215 1,210 1,205 1,200 0 20 40 60 80 100 Ta ambient temperature (°C) 120 0 20 40 60 80 100 120 Ta ambient temperature (°C) Figure 4 : Vsense pin input bias current vs Ambient Temperature 120 100 80 Iibv (nA) 60 V cc=5V 40 20 0 0 20 40 60 80 100 120 Ta ambient temperature (°C ) V cc=2,5V V cc=12V Figure 7 : Ictrl pin input bias current vs Ambient Temperature 30 28 26 Iibi ( A) 24 Vcc=12V 22 20 18 0 20 40 60 80 100 Ta ambient temperature (°C) 120 Victrl=200mV Vcc=5V Vcc=2,5V Figure 5 : Output short circuit current vs Ambient Temperature 60 50 40 Ios (mA) 30 20 10 0 0 20 40 60 80 100 Ta ambient temperature (°C) 120 Vcc=12V Vcc=5V Figure 8 : Supply current vs Ambient Temperature 1,6 Vcc=12V 1,4 1,2 Icc (mA) 1,0 0,8 0,6 Vcc=2,5V Vcc=5V Vcc=2,5V 0,4 0,2 0,0 0 20 40 60 80 100 Ta ambient temperature (°C) 120 5/9 TSM1051 PRINCIPLE OF OPERATION AND APPLICATION HINTS 1. Voltage and Current Control 1.1. Voltage Control The voltage loop is controlled via a first transconductance operational amplifier, the resistor bridge R1, R2, and the optocoupler which is directly connected to the output. The relation between the values of R1 and R2 should be chosen as written in Equation 1. R1 = R2 x Vref / (Vout - Vref) Eq1 Where Vout is the desired output voltage. To avoid the discharge of the load, the resistor bridge R1, R2 should be highly resistive. For this type of application, a total value of 100KΩ (or more) would be appropriate for the resistors R1 and R2. As an example, with R2 = 100KΩ, Vout = 4.10V, Vref = 1.210V, then R1 = 41.9KΩ. Note that if the low drop diode should be inserted between the load and the voltage regulation resistor bridge to avoid current flowing from the load through the resistor bridge, this drop should be taken into account in the above calculations by replacing Vout by (Vout + Vdrop). 1.2. Current Control The current loop is controlled via the second trans-conductance operational amplifier, the sense resistor Rsense, and the optocoupler. The control equation verifies: Rsense x Ilim = Vsense eq2 Rsense = Vsense / Ilim eq2’ where Ilim is the desired limited current, and Vsense is the threshold voltage for the current control loop. As an example, with Ilim = 1A, Vsense = -200mV, then Rsense = 200mΩ. Note that the Rsense resistor should be chosen taking into account the maximum dissipation (Plim) through it during full load operation. Plim = Vsense x Ilim. eq3 As an example, with Ilim = 1A, and Vsense = 200mV, Plim = 200mW. Therefore, for most adapter and battery charger applications, a quarter-watt, or half-watt resistor to make the current sensing function is sufficient. Vsense threshold is achieved internally by a resistor bridge tied to the Vref voltage reference. Its middle point is tied to the positive input of the current control operational amplifier, and its foot is to be connected to lower potential point of the sense resistor as shown on the following figure. The resistors of this bridge are matched to provide the best precision possible. The current sinking outputs of the two trans-conductance operational amplifiers are common (to the output of the IC). This makes an ORing function which ensures that whenever the current or the voltage reaches too high values, the optocoupler is activated. The relation between the controlled current and the controlled output voltage can be described with a square characteristic as shown in the following V/I output-power graph. Figure 9 : Output voltage versus output current Vout Voltage regulation Current regulation 0 TSM1051 Vcc : independent power supply Secondary current regulation Iout TSM1051 Vcc : On power output Primary current regulation 2. Compensation The voltage-control trans-conductance operational amplifier can be fully compensated. Both of its output and negative input are directly accessible for external compensation components. An example of a suitable compensation network is shown in Fig.2. It consists of a capacitor Cvc1=2.2nF and a resistor Rcv1=470KΩ in series, 6/9 TSM1051 connected in parallel with another capacitor Cvc2=22pF. The current-control trans-conductance operational amplifier can be fully compensated. Both of its output and negative input are directly accessible for external compensation components. An example of a suitable compensation network is shown in Fig.2. It consists of a capacitor Cic1=2.2nF and a resistor Ric1=22KΩ in series. When the Vcc voltage reaches 12V it could be interesting to limit the current coming through the output in the aim to reduce the dissipation of the device and increase the stability performances of the whole application. An example of a suitable Rout value could be 330Ω in series with the opto-coupler in case Vcc=12V. 3. Start Up and Short Circuit Conditions Under start-up or short-circuit conditions the TSM1051 is not provided with a high enough supply voltage. This is due to the fact that the chip has Figure 10 : its power supply line in common with the power supply line of the system. Therefore, the current limitation can only be ensured by the primary PWM module, which should be chosen accordingly. If the primary current limitation is considered not to be precise enough for the application, then a sufficient supply for the TSM1051 has to be ensured under any condition. It would then be necessary to add some circuitry to supply the chip with a separate power line. This can be achieved in numerous ways, including an additional winding on the transformer. The following schematic shows how to realize a low-cost power supply for the TSM1051 (with no additional windings). Please pay attention to the fact that in the particular case presented here, this low-cost power supply can reach voltages as high as twice the voltage of the regulated line. Since the Absolute Maximum Rating of the TSM1051 supply voltage is 14 V, this low-cost auxiliary power supply can only be used in applications where the regulated line voltage does not exceed 7 V. Vcc D To primary R2 OUT+ TSM105 Vcc Rs Rout IL Rvc1 Cvc2 22pF 470K Cvc1 1.210V Out + DS 200mV 2.2nF + Gnd Cic1 2.2nF Ric1 22K + CS + + Ictrl Vsense Ric2 500 R1 Vsense Rsense IL 7/9 Load OUT- TSM1051 PACKAGE MECHANICAL DATA 6 PINS - PLASTIC PACKAGE SOT23-6 Millimeters Dimensions Min. A A1 A2 B c D E e H L θ 0.9 0 0.9 0.35 0.09 2.8 1.5 0.95 2.6 0.1 0 3 0.6 10 deg. 0.102 0.004 0 Typ. Max. 1.45 0.15 1.3 0.5 0.2 3 1.75 Min. 0.035 0 0.035 0.0137 0.004 0.11 0.059 Inches Typ. Max. 0.057 0.006 0.0512 0.02 0.008 0.118 0.0689 0.0374 0.118 0.024 10 deg. 8/9 TSM1051 PACKAGE MECHANICAL DATA 8 PINS - PLASTIC MICROPACKAGE (SO8) Millimeters Dim. Min. A a1 a2 a3 b b1 C c1 D E e e3 F L M S 0.1 0.65 0.35 0.19 0.25 4.8 5.8 1.27 3.81 3.8 0.4 4.0 1.27 0.6 8° (max.) 0.150 0.016 Typ. Max. 1.75 0.25 1.65 0.85 0.48 0.25 0.5 45° (typ.) 5.0 6.2 0.189 0.228 Min. 0.004 0.026 0.014 0.007 0.010 Inches Typ. Max. 0.069 0.010 0.065 0.033 0.019 0.010 0.020 0.197 0.244 0.050 0.150 0.157 0.050 0.024 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 publication 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. © The ST logo is a registered trademark of STMicroelectronics © 2002 STMicroelectronics - Printed in Italy - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan - Malaysia Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States © http://www.st.com 9/9