ST STCF06 User Manual

1.5 A white LED driver with I²C interface

Features

■ Buck-boost DC-DC converter

■ Drives one power LED up to:

– 1.5 A between 3.5 V to 5.5 V
– 1.3 A between 3.0 V to 5.5 V
– 1 A between 2.7 V to 5.5 V

■ Efficiency up to 80%

■ Output current control

■ 1.8 MHz fixed frequency PWM

■ Full I²C control

■ Operational modes:

– Shutdown mode
– Ready mode + auxiliary red LED
– Ready mode + NTC
– Flash mode: up to 1.5 A
– Torch mode: up to 370 mA

■ Soft and hard triggering of flash

■ Flash and torch dimming with 16 exponential

values

■ Dimmable red LED indicator auxiliary output

■ Internally or externally timed flash operation

■ Digitally programmable safety time-out in flash

mode

■ LED over temperature detection and protection

with external NTC resistor

■ Open and shorted LED failure detection and

protection

■ Chip over temperature detection and protection

■ < 1 µA shutdown current

■ Package 3 x 3 mm TFBGA25

STCF06

TFBGA25 (3 x 3 mm)

Applications

■ Cell phones and smart phones

■ Camera flashes/strobe

■ PDAs and digital still cameras

Description

The STCF06 is a high efficiency power supply
solution to drive a single flash LED in camera
phones, PDAs and other battery powered
devices. It is a buck-boost converter able to
guarantee a proper LED current control over all
possible conditions of battery voltage and LED
forward voltage. The output current control
ensures a good current regulation over the
forward voltage spread characteristics of the flash
LED. All the functions of the device are controlled
through the I²C bus which helps to reduce logic
pins on the package and to save PCB tracks on
the board. Hard and soft-triggering of flash are
both supported. The device includes many
functions to protect the chip and the power LED,
such as: soft start control, chip over temperature,
open and shorted LED detection and protection.

Table 1. Device summary

Order code Package Packaging

STCF06TBR TFBGA25 (3 x 3 mm) 3500 parts per reel

July 2010 Doc ID 14549 Rev 3 1/35

www.st.com

35

Contents STCF06

Contents

1 Description (continued) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

5 Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

6 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

7 Detailed description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.2 Buck-boost converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.3 Logic pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.3.1 SCL, SDA pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.3.2 TRIG pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.3.3 ATN pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.3.4 ADD pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7.3.5 TMSK pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7.4 Power-on reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7.5 Shutdown, shutdown with NTC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7.6 Ready mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

7.7 Single or multiple flash using external (microprocessor) temporization . . 15

7.8 External (microprocessor) temporization using TRIG_EN bit . . . . . . . . . 15

7.9 Single flash using internal temporization . . . . . . . . . . . . . . . . . . . . . . . . . 15

7.10 Multiple flash using internal temporization . . . . . . . . . . . . . . . . . . . . . . . . 16

8 I²C bus interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

8.1 Data validity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

8.2 Start and stop conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

8.3 Byte format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2/35 Doc ID 14549 Rev 3

STCF06 Contents

8.4 Acknowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

8.5 Writing to a single register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

8.6 Interface protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

8.7 Writing to multiple registers with incremental addressing . . . . . . . . . . . . 20

8.8 Reading from a single register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

8.9 Reading from multiple registers with incremental addressing . . . . . . . . . 21

9 Description of internal registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

9.1 PWR_ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

9.2 TRIG_EN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

9.3 TCH_ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

9.4 NTC_ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

9.5 FTIM_0~3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

9.6 TDIM_0~3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

9.7 FDIM_0~3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

9.8 AUXI_0~3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

9.9 AUXT_0~3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

9.10 F_RUN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

9.11 LED_F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

9.12 NTC_W . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

9.13 NTC_H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

9.14 OT_F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

9.15 VOUTOK_N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

10 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

11 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

12 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Doc ID 14549 Rev 3 3/35

List of tables STCF06

List of tables

Table 1. Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Table 2. Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Table 3. Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Table 4. Thermal data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Table 5. List of external components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Table 6. Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Table 7. Address table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Table 8. Interface protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Table 9. I²C register mapping function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Table 10. Command register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Table 11. Dimming register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Table 12. Auxiliary register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Table 13. Auxiliary LED dimming table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Table 14. Torch mode and flash mode dimming registers settings . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Table 15. Status register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Table 16. Status register details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Table 17. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

4/35 Doc ID 14549 Rev 3

STCF06 List of figures

List of figures

Figure 1. Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Figure 2. Pin connections (top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Figure 3. Application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 4. Data validity on the I²C bus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 5. Timing diagram on I²C bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 6. Bit transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 7. Acknowledge on I²C bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 8. Writing to a single register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Figure 9. Writing to multiple register with incremental addressing. . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 10. Reading from a single register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 11. Reading from multiple registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 12. Flash and torch current vs. dimming value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figure 13. VOUTOK_N behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Figure 14. Efficiency vs. V
Figure 15. Efficiency vs. V
Figure 16. Maximum output current vs. V

Figure 17. Flash current vs. temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Figure 18. Input current vs. V
Figure 19. Input current vs. V
Figure 20. I
Figure 21. I

flash vs. FDIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

LED

torch vs. TDIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

LED

Figure 22. Flash time dimming steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

flash mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

BAT

, torch mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

BAT

BAT

BAT

(V
(I

LED

LED

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

BAT

= 3.75 V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

= 1 A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Doc ID 14549 Rev 3 5/35

Description (continued) STCF06

1 Description (continued)

In addition, a digital programmable time-out function protects the LED in case of a wrong
command from the microcontroller. An optional external NTC resistor is supported to protect
the LED against over heating.

In mobile phone applications, it is possible to reduce immediately the flash LED current
during the signal transmission using the TMSK pin. This saves battery life and gives more
priority to supply RF transmission instead of flash function.

Dedicated I²C commands allow to separately program the current intensity in flash and torch
mode using exponential steps. An auxiliary output controls an optional red LED to be used
as a recording indicator.

The device is packaged in 3 x 3 mm TFBGA25 with 1 mm height.

6/35 Doc ID 14549 Rev 3

STCF06 Diagram

2 Diagram

Figure 1. Block diagram

Doc ID 14549 Rev 3 7/35

Pin configuration STCF06

3 Pin configuration

Figure 2. Pin connections (top view)

Table 2. Pin description

Pin n° Symbol Name and function

E1,D2 VLX2 Inductor connection

B3 RX RX resistor connection

D1,C2 VOUT Output voltage

A4 NTC NTC resistor connection

B5 FB1 Feedback pin [I

A5 FB2 R

bypass

TR

B4 FB2S Feedback pin [I

*(RFL+RTR)]

LED

LED*RFL

]

E2 GND Signal ground

C5 TMSK TX mask input

D5 AUXL Auxiliary LED output

D4 ADD I²C address selection

A3 VBAT Supply voltage

B1,C1 PVBAT Power supply voltage

A2 VLX1A Inductor connection

A1, B2 VLX1B Inductor connection

E4 ATN Attention (open drain output, active LOW)

E3 SDA I²C data

C3, D3 PGND Power ground

E5 SCL I²C clock signal

C4 TRIG Flash trigger input

8/35 Doc ID 14549 Rev 3

STCF06 Maximum ratings

4 Maximum ratings

Table 3. Absolute maximum ratings

Symbol Parameter Value Unit

VBAT Signal supply voltage -0.3 to 6 V

PVBAT Power supply voltage -0.3 to 6 V

VLX1A, VLX1B Inductor connection 1 –0.3 to V

VLX2 Inductor connection 2 –0.3 to V

+0.3 V

I

+0.3 V

O

VOUT Output voltage -0.3 to 6 V

AUXL Auxiliary LED –0.3 to V

+0.3 V

BAT

FB1, FB2, FB2S Feedback and sense voltage -0.3 to 3 V

SCL, SDA, TRIG,
ATN, ADD TMSK

R

X

Logic pin -0.3 to V

Connection for reference resistor -0.3 to 3 V

+0.3 V

BAT

NTC Connection for LED Temperature sensing -0.3 to 3 V

ESD Human body model ± 2kV

P

T

T

STG

TOT

OP

T

J

Continuous power dissipation (at TA = 70°C) 800 mW

Operating junction temperature range -40 to 85 °C

Junction temperature -40 to 150 °C

Storage temperature range -65 to 150 °C

Note: Absolute maximum ratings are those values beyond which damage to the device may occur.

Functional operation under these condition is not implied.

Table 4. Thermal data

Symbol Parameter Value Unit

R

thJA

Thermal resistance junction-ambient 58 °C/W

Doc ID 14549 Rev 3 9/35

Application STCF06

5 Application

Figure 3. Application schematic

C

C

O

O

4.7µF

4.7µF

R

R

TR

TR

R

R

FL

FL

**: Connect to VI, or GND or SDA or SCL to choose one of the 4 different I²C Slave Addresses.

***: Optional components to support auxiliary functions. V

Table 5. List of external components

ref_ext

= 1.8 V

Component Manufacturer Part number Value Size

C

I

C

O

TDK C1608X5R0J106M 2 x 10 µF 0603

TDK C1608X5R0J475M 4.7 µF 0603

L (max flash 1.5 A) TDK VLF4014A-1R51R8-1 1.5 µH 3.8x3.5x1.4 [mm]

NTC Murata NCP21WF104J03RA 100 kΩ 0805

R

FL

R

TR

R

X

Tyco RL73K1JR15JTD 0.15 Ω 0603

Tyco CRG0805F1R0 1 Ω 0805

Rohm MCR01MZPJ15K 15 kΩ 0402

LED Luxeon LED LXCL-PWF1

D

1. Due to the increased voltage drop, the output current performance is decreased.

STMicroelectro
nics

(best performance)

(1)

BAT20J

(smaller size) 2.7x1.35x1.13 [mm]

STPS1L20MF

3.8x1.9x0.85 [mm]

Note: All of the above listed components refer to typical application. Operation of the STCF06 is

not limited to the choice of these external components.

10/35 Doc ID 14549 Rev 3

STCF06 Electrical characteristics

6 Electrical characteristics

TJ = -40 to 85 °C, V
Ω, R

Table 6. Electrical characteristics

= 1 Ω, RX = 15 kΩ, typ. values are at TJ = 25 °C, unless otherwise specified.

TR

BAT

= PV

= 3.6 V, 2 x CI = 10 µF, CO = 4.7 µF, L = 1.5 µH, RFL = 0.15

BAT

Symbol Parameter Test condition Min. Typ. Max. Unit

V

Input operation supply voltage 2.7 5.5 V

I

V

PW_ON

RESET

Power-ON reset threshold VI rising 2.3 V

Flash mode for VI = 3.5 V to 5.5 V 117 1500
Output current adjustment
range I

FLASH

Flash mode for V

Flash mode for V

I

O

Output current adjustment
range I

TORC H

Auxiliary LED output current
adjustment range I

V

Regulated voltage range 2.5 5.0 V

O

AUXLED

Torch mode VI = 2.7 V to 5.5 V 29 370

Ready mode, VI = 2.7 V to 5.5 V 0 20

= 3.0 V to 3.3 V 117 1300

I

= 2.7 V to 5.5 V 117 1000

I

FB1 Feedback voltage Torch mode 30 250 mV

FB2 Feedback voltage Flash mode 30 250 mV

R

ΔI

ON_

I

Output current tolerance Flash mode, IO = 160 mV/R

O

FL

FB1-FB2 ON resistance Torch mode, IO = 200 mA 90 mΩ

Quiescent current in
SHUTDOWN mode

Q

Quiescent current in ready ­mode

-10 10 %

1µA

1.8 mA

mA

Frequency VI = 2.7 V 1.8 MHz

f

s

Efficiency of the chip itself

(1)

ν

Efficiency of the whole
application

OVP Output over voltage protection V

OV

OT

V

OTP

REF5

Over voltage hysteresis VI = 5.5 V, No Load 0.2 V

HYST

Junction over temperature
protection

Junction over temperature

HYST

hysteresis

NTC hot voltage threshold Ready mode, I

(2)

VI = 3.2 to 4.2 V, Flash Mode,

= 2200 mA

I

O

80

VI = 3.2 to 4.2 V, Flash Mode,

IO = 2200 mA, VO=V

fLED_max

5.02 V

See the typical application schematic

+ V

FB2

=

70

It is included losses of inductor and

sensing resistor

= 5.5 V, No Load 5.3 V

I

140 °C

20 °C

= 2mA max 1.2 V

NTC

Doc ID 14549 Rev 3 11/35

%