Datasheet

ManualsBrandsSTMICROELECTRONICS ManualsPMICsPMIC - LED driver Linear PowerSO 10 Surface-mount

July 2008 Rev 4 1/16

STCS2

2 A max constant current LED driver

Features

■ Up to 40 V input voltage

■ Less than 0.5 V voltage overhead

■ Up to 2 A output current

■ PWM dimming pin

■ Shutdown pin

■ LED disconnection diagnostic

Applications

■ LED constant current supplying for varying

input voltages

■ Low voltage lighting

■ Small appliances LED lighting

■ Car LED lights

Description

The STCS2 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 2 A

with a ± 10 % precision; a dedicated pin allows

implementing PWM dimming.

An open-drain pin output provides information on

load disconnection condition.

PowerSO-10

Table 1. Device summary

Order code Package Packaging

STCS2SPR PowerSO-10 600 parts per reel

www.st.com

Summary of content (16 pages)

PAGE 1
STCS2 2 A max constant current LED driver Features ■ Up to 40 V input voltage ■ Less than 0.
PAGE 2
Contents STCS2 Contents 1 Application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5 Timing . . . . . . . . . . . . . . . . . . . . .
PAGE 3
STCS2 Application diagram 1 Application diagram Figure 1. Typical application diagram for 2 A LED current VIN 4.5V up to 40V RIN 100 ohm CBYP 0.1µF ON VCC PWM OFF ON OFF DRAIN STCS2 CDRAIN 0.47µF EN DISC Load disconnection (Open Drain output) GND FB SOURCE RFB 0.
PAGE 4
Pin configuration STCS2 2 Pin configuration Figure 2. Pin connections (top view) Table 2. Pin description Pin n° Symbol 1 VCC 2 PWM 3 EN Shutdown 4 N.C. Not connected 5 DRAIN 6 SOURCE Internal N-MOSFET SOURCE. Reference voltage is 100 mV. An external resistor between SOURCE and GND pins sets different current levels for different application needs 7 FB Feedback input. The control loop regulates the current in such a way that the average voltage at the FB input is 100 mV (nominal).
PAGE 5
STCS2 Maximum ratings 3 Maximum ratings Table 3. Absolute maximum ratings Symbol Parameter VCC Value Unit DC supply voltage -0.3 to +45 Drain pin -0.3 to +45 SOURCE Source pin -0.3 to + 3.3 V PWM, EN, DISC Logic pins -0.3 to + VCC + 0.3 V -0.3 to + 3.3 V ±2 kV V DRAIN FB Configuration pins ESD Human body model (all pins) TJ (1) Junction temperature -40 to 150 °C TSTG Storage temperature range -55 to 150 °C 1.
PAGE 6
Electrical characteristics STCS2 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 2000 mA Output current RFB = 50 mΩ Regulation (percentage with respect to VCC=12V) VCC = 4.
PAGE 7
STCS2 Timing 5 Timing Figure 3. PWM and output current timing PWM 90% Current 10% Trise TD Figure 4. TD Block diagram High Voltage 45 V VCC Tfall Preregulator 3.3 V Low Voltage 3.3 V H.V. 45 V Thermal Shutdown Bandgap 1.
PAGE 8
Typical performance characteristics STCS2 6 Typical performance characteristics Figure 5. IDRAIN vs VCC, TA = 25 °C Figure 6. IDRAIN vs RSET 1000 IDRAIN [mA] 100 10 1 0.1 1 10 RFB [Ω] Figure 7. IDRAIN vs temperature Figure 8. Figure 9. ICC vs temperature Figure 10.
PAGE 9
STCS2 7 Detail description Detail description The STCS2 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.
PAGE 10
Application information STCS2 8 Application information 8.1 Reverse polarity protection STCS2 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
STCS2 Application information 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: 1000 mA; – Package: Power SO-10; – TA = 50 °C; In this case the drain voltage is given by: VDRAIN = 12 - 3 x 3.6 = 1.2 V end the power dissipated in the IC is the following: PD = (1.2 - 0.1) x 1 + 12 x 0.5 x 10-3 = 1.
PAGE 12
Package mechanical data 9 STCS2 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.
PAGE 13
STCS2 Package mechanical data PowerSO-10 mechanical data Dim. mm. Min. Typ. inch. Max. Min. Typ. Max. A 3.70 0.146 A1 0.10 0.004 A2 3.40 3.60 0.134 0.142 A3 1.25 1.35 0.049 0.053 b 0.40 0.53 0.016 0.021 c 0.35 0.55 0.014 0.022 D 9.40 9.60 0.370 0.378 D1 7.40 7.60 0.291 0.299 E 13.80 14.40 0.543 0.567 E1 9.30 9.50 0.366 0.374 E2 7.20 7.60 0.283 0.299 E3 5.90 6.10 0.232 0.240 e 1.27 0.050 L 0.95 1.65 0.037 0.
PAGE 14
Package mechanical data STCS2 Tape & reel PowerSO-10 mechanical data mm. inch. Dim. Min. A Max. Min. 330 13.2 Typ. Max. 12.992 C 12.8 D 20.2 0.795 N 60 2.362 T 14/16 Typ. 0.504 30.4 0.519 1.197 Ao 14.9 15.1 0.587 0.594 Bo 9.9 10.1 0.390 0.398 Ko 4.15 4.35 0.163 0.171 Po 3.9 4.1 0.153 0.161 P 23.9 24.1 0.941 0.949 W 23.7 24.3 0.933 0.
PAGE 15
STCS2 Revision history 10 Revision history Table 6. Document revision history Date Revision Changes 03-Oct-2007 1 Initial release. 15-Feb-2008 2 Modified: Figure 1 on page 3, Figure 4 on page 7, Figure 12 on page 11. 05-May-2008 3 Modified: Table 2 on page 4, pin 9 description. 02-Jul-2008 4 Modified: Table 5 on page 6.
PAGE 16
STCS2 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.