STCS1APUR

STCS1A 1.5 A max constant current LED driver Datasheet - production data Description DFN8 (3 x 3 mm) The STCS1A is a BiCMOS constant current source designed to provide a precise constant current starting from a varying input voltage source. The main target is to replace discrete components solution for driving LEDs in low voltage applications such as 5 V, 12 V or 24 V giving benefits in terms of precision, integration and reliability. PowerSO-8 The current is set with external resistor up to 1.5 A with a ± 10 % precision; a dedicated pin allows implementing PWM dimming. An external capacitor allows setting the slope for the current rise from tens of microseconds to tens of milliseconds allowing reduction of EMI. Features • Up to 40 V input voltage • Less than 0.5 V voltage overhead An open-drain pin output provides information on load disconnection condition. • Up to 1.5 A output current • PWM dimming pin • Shutdown pin • LED disconnection diagnostic • Slope control with external cap Applications • LED constant current supplying for varying input voltages • Low voltage lighting • Small appliances LED lighting Table 1. Device summary Order codes Packages Packaging STCS1APUR DFN8 (3 x 3 mm) 3000 parts per reel STCS1APHR PowerSO-8 2500 parts per reel January 2022 This is information on a product in full production. DocID14455 Rev 3 1/19 www.st.com Contents STCS1A Contents 1 Application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5 Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 7 Detail description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 8 7.1 Current setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.2 Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.3 PWM dimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.4 Diagnostic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 8.1 Reverse polarity protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 8.2 Thermal considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 9 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2/19 DocID14455 Rev 3 STCS1A 1 Application diagram Application diagram Figure 1. Typical application diagram for 0.5 A LED current VIN 4.5V to 40V BAT46ZFILM RIN 100 ohm CBYP 0.1µF VCC ON PWM ON EN OFF OFF DISC Load disconnection (Open Drain output) DRAIN STCS1A CDRAIN 0.47µF SLOPE GND FB CSLOPE 10nF DocID14455 Rev 3 RFB 0.2 ohm 3/19 19 Pin configuration 2 STCS1A Pin configuration Figure 2. Pin connections (top view) PowerSO-8 DFN8 Table 2. Pin description Pin n° Symbol 1 VCC 2 PWM 3 EN 4 DRAIN 5 FB 6 GND 7 SLOPE 8 DISC Exp-pad 4/19 Note Supply voltage PWM dimming input Shutdown pin Internal N-MOSFET drain Feedback input. The control loop regulates the current in such a way that the average voltage at the FB input is 100 mV (nominal). The cathode of the LED and a resistor to ground to set the LED current should be connected at this point Ground Capacitor for slope control Load disconnection flag (open drain) Internally connected to ground DocID14455 Rev 3 STCS1A 3 Maximum ratings Maximum ratings Table 3. Absolute maximum ratings Symbol Parameter VCC Value Unit DC supply voltage -0.3 to +45 DRAIN Drain pin -0.3 to +45 PWM, EN, DISC Logic pins -0.3 to + VCC + 0.3 V -0.3 to + 3.3 V ±2 kV SLOPE, FB Configuration pins V ESD Human body model (all pins) TJ (1) Junction temperature -40 to 150 °C TSTG Storage temperature range -55 to 150 °C 1. TJ is calculated from the ambient temperature TA and the power dissipation PD according the following formula: TJ = TA + (PD x RthJA). See Figure 16 and Figure 17 for details of max power dissipation for ambient temperatures higher than 25°C. Note: Absolute maximum ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is not implied. Table 4. Thermal data Symbol RthJC RthJA Parameter Thermal resistance junction-case Thermal resistance junction-ambient DFN8 PowerSO-8 Unit 10 12 °C/W 37.6 (1) 45 (2) °C/W 1. This value is referred to four-layer PCB, JEDEC standard test board. 2. With two sides, two planes PCB following EIA/JEDEC JESD51-7 standard. DocID14455 Rev 3 5/19 19 Electrical characteristics 4 STCS1A Electrical characteristics VCC = 12 V; IO = 100 mA; TJ = -40 °C to 125 °C; VDRAIN = 1 V; CDRAIN = 1 µF; CDRAIN = 1 µF, CBYP = 100 nF typical values are at TA = 25 °C, unless otherwise specified. Table 5. Electrical characteristics Symbol VCC Parameter Test conditions Min. 40 V Output current range 1 1500 mA Regulation (percentage with respect to VCC = 12 V) VCC = 4.5 to 40 V, IO = 100 mA; VDRAIN = 1 V -1 VFB Feedback voltage IO = 0 to 1.5 A 90 ICC Quiescent current (Measured on VCC pin) 500 On Mode Dropout voltage (VDRAIN to GND) LEAKDRAIN Drain leakage current TR/TF TD DISC Thermal Protection Unit 4.5 RFB = 0.2 Ω VDROP Max. Supply voltage range Output current IO Typ. Rise/Fall time of the current on PWM transition +1 % 100 110 mV 450 750 Shutdown Mode;VCC = 5 to 12 V 1 Shutdown Mode;VCC = 12 to 40 V 3 IO = 100 mA 0.12 0.16 IO = 1.5 A 0.58 0.9 Shutdown; VDRAIN = 40 V 10 CSLOPE = 10 nF, TJ = -40 °C to 105 °C 800 VPWM rising, VCC = 12 V CSLOPE = floating 3 VPWM falling, VCC = 12 V CSLOPE = floating 1.2 Low level voltage ISINK = 5 mA 0.2 Leakage current VDISC = 5 V Load disconnection threshold (VDRAIN-GND) DISC Turn-ON 75 DISC Turn-OFF 110 Delay on PWM signal (see Figure 3) mA µA V µA µs µs Shutdown temperature 155 Hysteresis 25 0.5 V 1 µA mV °C Logic inputs (PWM and EN) VL Input low level VH Input high level Note: 6/19 0.4 1.2 V V EN, PWM leakage current VEN = 5 V; VPWM = 5 V 2 EN input leakage current VEN = 40 V 60 PWM input leakage current VPWM = 40 V 120 µA All devices 100 % production tested at TA = 25 °C. Limits over the operating temperature range are guaranteed by design. DocID14455 Rev 3 STCS1A 5 Timing Timing Figure 3. PWM and output current timing PWM 90% Current 10% TD Trise TD Tfall Figure 4. Block diagram High Voltage 45 V VCC Preregulator 3.3 V Low Voltage 3.3 V H.V. 45 V Thermal Shutdown Bandgap 1.23 V DISC Shutdown all blocks + 75 mV EN Enable Input PWM PWM Input Enable, PWM & Slope controll Logic Disc comp DRAIN + Logic 100 mV Comp GND Slope Control Driver FB SLOPE DocID14455 Rev 3 7/19 19 Typical performance characteristics 6 8/19 STCS1A Typical performance characteristics Figure 5. IDRAIN vs. VCC, TA = 25 °C Figure 6. IDRAIN vs. RSET Figure 7. IDRAIN vs. temperature Figure 8. VDROP (including VFB) vs. temperature Figure 9. ICC vs. temperature Figure 10. ICC vs. VCC DocID14455 Rev 3 STCS1A Typical performance characteristics Figure 11. Trise/Tfall vs CSLOPE Figure 12. Turn-on time CSLOPE = floating Figure 13. Dimming operation: Rise CSLOPE = 1 nF Figure 14. Dimming operation: Fall CSLOPE = 1 nF DocID14455 Rev 3 9/19 19 Detail description 7 STCS1A Detail description The STCS1A is a BiCMOS constant current source designed to provide a precise constant current starting from a varying input voltage source. The main target is to replace discrete components solution for driving LEDs in low voltage applications such as 5 V, 12 V or 24 V giving benefits in terms of precision, integration and reliability. 7.1 Current setting The current is set with an external sensing resistor connected to the FB pin. The feedback voltage is 100 mV, then a low resistor value can be chosen reducing power dissipation. A value between 1 for instance, should one need a 700 mA LEDs current, RF should be selected according to the following equation: For instance, should one need a 700 mA LEDs current, RF should be selected according to the following equation: RF = VFB / ILEDs = 100 mV / 700 mA = 142 mΩ 7.2 Enable When the enable pin is low the device completely off thus reducing current consumption to less than 1 µA. When in shutdown mode, the internal main switch is off. 7.3 PWM dimming The PWM input allows implementing PWM dimming on the LED current; when the PWM input is high the main switch will be on and vice versa. A typical frequency range for the input is from few Hertz to 50 kHz. The maximum dimming frequency is limited by the minimum rise/fall time of the current (obtained with CSLOPE = 0) which is around 4µs each. Above 50 kHz the current waveforms starts assuming a triangular shape. While the PWM input is switching, the overall circuitry remains on, this is needed in order to implement two important features: short delay time and controlled slope for the current. Since the PWM pin is controlling just the main switch, the overall circuitry is always on and it is able to control the delay time between the PWM input signal and the output current in the range of few µs, this is important to implement synchronization among several light LED sources. The rise and fall slope of the current is controlled by the CSLOPE capacitor. The rise and fall time are linear dependent from the CSLOPE capacitor value (see graph in typical characteristics). A controlled rise time has two main benefits: reducing EMI noise and avoid current spike at turn on. When CSLOPE is left floating, the internal switch is turned on at maximum speed, in this condition an overshoot can be present on the LED current before the system goes into regulation. 10/19 DocID14455 Rev 3 STCS1A 7.4 Detail description Diagnostic When STCS1A is in on mode (EN is high), the device is able to detect disconnection or fail of the LED string monitoring VDRAIN pin. If VDRAIN is lower than 75 mV the DISC pin is pulled low regardless the PWM pin status. This information can be used by the system to inform that some problem happens in the LEDs. DocID14455 Rev 3 11/19 19 Application information STCS1A 8 Application information 8.1 Reverse polarity protection STCS1A must be protected from reverse connection of the supply voltage. Since the current sunk from VCC pin is in the range of 450 µA a small diode connected to VCC is able to protect the chip. Care must be taken for the whole application circuit, especially for the LEDs, in fact, in case a negative voltage is applied between VIN and GND, a negative voltage will be applied to the LED string that must have a total breakdown voltage higher than the negative applied voltage in order to avoid any damage. Figure 15. Reverse polarity condition VIN BAT46 or similar DRAIN VCC PWM EN DISC + 8.2 SLOPE GND FB Thermal considerations The STCS1A is able to control a LED current up to 1.5 A and able to sustain a voltage on the drain pin up to 40 V. Those operating conditions are however limited by thermal constraints, the thermal resistances shown in the Table 4: Thermal data section are the typical ones, in particular RthJA depends on the copper area and the number of layers of the printed circuit board under the pad. DFN8 and PowerSO-8 have an exposed die attach pad which enhances the thermal conductivity enabling high power application. The power dissipation in the device can be calculated as follow: PD = (VDRAIN - VFB) x ILED + (VCC x ICC) basing on this and on the thermal resistance and ambient temperature, the junction temperature can be calculated as: TJ = RthJA x PD + TA A typical application could be: – Input voltage: 12 V; – 3 white LEDs with an typical VF = 3.6 V; – LEDs current: 500 mA; 12/19 DocID14455 Rev 3 STCS1A Application information – Package: DFN8 3 x 3 mm; – TA = 50 °C; In this case VDRAIN = 12 - 3 x 3.6 = 1.2 V PD = (1.2 - 0.1) x 0.5 + 12 x 0.5 x 10-3 = 0.55 + 6 x 10-3 = 556 mW The junction temperature will be: TJ = 37.6 x 0.556 + 50 = 70.9 °C. The following pictures show the maximum power dissipation according to the ambient temperature for both packages: Figure 16. Maximum power dissipation vs TA for Figure 17. Maximum power dissipation vs TA for DFN8 3x3 mm PowerSO-8 3.00 3.50 RthJA = 38 [°C/W] 3.00 PDMAX [W] 2.50 PDMAX [W] RthJA = 45 [°C/W] 2.50 2.00 1.50 1.00 2.00 1.50 1.00 0.50 0.50 PDMAX = (TJMAX-TA)/RthJA 0.00 25 35 45 55 65 75 PDMAX = (TJMAX-TA)/RthJA 0.00 85 95 105 115 125 25 35 45 55 65 75 85 95 105 115 125 [°C] [°C] DocID14455 Rev 3 13/19 19 Package mechanical data 9 STCS1A Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK® is an ST trademark. 14/19 DocID14455 Rev 3 STCS1A Package mechanical data DFN8 (3x3 mm) mechanical data mm. mils. Dim. Min. Typ. Max. Min. Typ. Max. 0.80 0.90 1.00 31.5 35.4 39.4 A1 0.02 0.05 0.8 2.0 A2 0.70 27.6 A3 0.20 7.9 A b 0.18 D D2 2.23 7.1 2.38 1.49 1.64 2.48 87.8 0.40 11.8 93.7 97.7 118.1 1.74 58.7 0.50 0.30 9.1 118.1 3.00 e L 0.30 3.00 E E2 0.23 64.6 68.5 19.7 0.50 DocID14455 Rev 3 11.8 15.7 19.7 15/19 19 Package mechanical data STCS1A PowerSO-8 mechanical data Dim. mm. Min. Typ. A inch. Max. Min. Typ. 1.70 A1 0.00 A2 1.25 b 0.31 c 0.17 D 4.80 D1 0.067 0.00 0.006 0.049 0.142 0.51 0.012 0.020 0.25 0.007 0.010 4.90 5.00 0.189 0193 0.197 2.24 3.10 3.20 0.088 0.122 0.126 E 5.80 6.00 6.20 0.228 0.236 0.244 E1 3.80 3.90 4.00 0.150 0.154 0.157 E2 1.55 2.41 2.51 0.061 0.095 0.099 e 0.15 Max. 1.27 0.050 h 0.25 0.50 0.010 0.020 L 0.40 1.27 0.016 0.050 k 0° 8° 0° 8° ccc 0.10 0.004 7195016C 16/19 DocID14455 Rev 3 STCS1A Package mechanical data Tape & reel QFNxx/DFNxx (3x3) mechanical data mm. inch. Dim. Min. Typ. A Max. Min. Typ. 180 13.2 7.087 C 12.8 D 20.2 0.795 N 60 2.362 T 0.504 0.519 14.4 0.567 Ao 3.3 0.130 Bo 3.3 0.130 Ko 1.1 0.043 Po 4 0.157 P 8 0.315 DocID14455 Rev 3 Max. 17/19 19 Revision history 10 STCS1A Revision history Table 6. Document revision history Date Revision 19-Feb-2008 1 Initial release. 02-Jul-2008 2 Modified: Table 5 on page 6. 20-Jan-2022 3 Updated: Applications on the cover page. 18/19 Changes DocID14455 Rev 3 STCS1A IMPORTANT NOTICE – PLEASE READ CAREFULLY STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, enhancements, modifications, and improvements to ST products and/or to this document at any time without notice. Purchasers should obtain the latest relevant information on ST products before placing orders. ST products are sold pursuant to ST’s terms and conditions of sale in place at the time of order acknowledgement. Purchasers are solely responsible for the choice, selection, and use of ST products and ST assumes no liability for application assistance or the design of Purchasers’ products. No license, express or implied, to any intellectual property right is granted by ST herein. Resale of ST products with provisions different from the information set forth herein shall void any warranty granted by ST for such product. ST and the ST logo are trademarks of ST. For additional information about ST trademarks, please refer to www.st.com/trademarks. All other product or service names are the property of their respective owners. Information in this document supersedes and replaces information previously supplied in any prior versions of this document. © 2022 STMicroelectronics – All rights reserved DocID14455 Rev 3 19/19 19