Datasheet

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July 2008 Rev 8 1/17

STCS1

1.5 A max constant current LED driver

Features

■ Up to 40 V input voltage

■ Less than 0.5 V voltage overhead

■ Up to 1.5 A output current

■ PWM dimming pin

■ Shutdown pin

■ LED disconnection diagnostic

Applications

■ Supplying LEDs with constant current for

varying input voltages

■ Low voltage lighting

■ Small appliance LED lighting

■ Car LED lights

Description

The STCS1 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.

The current is set with external resistor up to 1.5

A with a ± 10 % precision; a dedicated pin allows

implementing PWM dimming.

An open-drain pin output provides information on

load disconnection condition.

PowerSO-8

DFN8 (3x3 mm)

Table 1. Device summary

Order codes Packages Packaging

STCS1PUR DFN8 (3 x 3 mm) 3000 parts per reel

STCS1PHR PowerSO-8 2500 parts per reel

www.st.com

Summary of content (17 pages)

PAGE 1
STCS1 1.5 A max constant current LED driver Features ■ Up to 40 V input voltage ■ Less than 0.5 V voltage overhead ■ Up to 1.5 A output current ■ PWM dimming pin ■ Shutdown pin ■ LED disconnection diagnostic DFN8 (3x3 mm) PowerSO-8 Applications ■ Supplying LEDs with constant current for varying input voltages ■ Low voltage lighting ■ Small appliance LED lighting ■ Car LED lights The current is set with external resistor up to 1.
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Contents STCS1 Contents 1 Application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5 Timing . . . . . . . . . . . . . . . . . . . . .
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STCS1 Application diagram 1 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 ON PWM ON EN DISC OFF OFF DRAIN VCC Load disconnection (Open Drain output) STCS1 CDRAIN 0.47µF GND FB RFB 0.
PAGE 4
Pin configuration STCS1 2 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 Ground 7 N.C. In order to guarantee the device works properly it is mandatory to leave this pin floating 8 DISC Load disconnection flag (open drain) Exp-pad 4/17 Note Supply voltage PWM dimming input Shutdown pin Internal N-MOSFET drain Feedback input.
PAGE 5
STCS1 Maximum ratings 3 Maximum ratings Table 3. Absolute maximum ratings Symbol VCC Parameter 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 Junction temperature -40 to 150 °C Storage temperature range -55 to 150 °C FB ESD TJ (1) TSTG V Configuration pins Human body model (all pins) 1.
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Electrical characteristics STCS1 4 Electrical characteristics Table 5. Electrical characteristics (VCC = 12 V; IO = 100 mA; TJ = -40 °C to 125 °C; VDRAIN = 1 V; CDRAIN = 1 µF; CBYP = 100 nF typical values are at TA = 25 °C, unless otherwise specified) Symbol VCC IO VFB Parameter Test conditions Min. VDROP 40 V Output current range 1 1500 mA Output current RFB = 0.2 Ω Regulation (percentage with respect to VCC=12V) VCC = 4.
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STCS1 Timing 5 Timing Figure 3. PWM and output current timing PWM 90% Current 10% Trise TD Figure 4. Block diagram High Voltage 45 V VCC Tfall TD Preregulator 3.3 V Low Voltage 3.3 V H.V. 45 V Thermal Shutdown Bandgap 1.
PAGE 8
Typical performance characteristics STCS1 6 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.
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STCS1 7 Detail description Detail description The STCS1 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.
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Application information STCS1 8 Application information 8.1 Reverse polarity protection STCS1 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.
PAGE 11
STCS1 Application information – Package: DFN8 3x3 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 12. Maximum power dissipation vs TA for DFN8 3x3 mm Figure 13. Maximum power dissipation vs TA for PowerSO-8 3.00 3.
PAGE 12
Package mechanical data 9 STCS1 Package mechanical data In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a lead-free second level interconnect. The category of second Level Interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.
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STCS1 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 11.8 15.7 19.
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Package mechanical data STCS1 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.
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STCS1 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 Max. 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.
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Revision history STCS1 10 Revision history Table 6. Document revision history Date Revision 10-Apr-2007 1 Initial release. 07-May-2007 2 PowerSO-8 mechanical data has been updated and the RthJC for PowerSO-8 value on Table 4 is changed. 24-May-2007 3 Change value CBYP 0.1µF ==> 1 µF on Figure 1 typical application. 27-Sep-2007 4 Add RIN on Figure 1 application diagram. 02-Oct-2007 5 Figure 1 updated.
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STCS1 Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale.