Epson S1F76680 User manual

Rev.1.22
S1F76680
Technical Manual
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NOTICE
No part of this material may be reproduced or duplicated in any form or by any means without the written
permission of Seiko Epson. Seiko Epson reserves the right to make changes to this material without notice.
Seiko Epson does not assume any liability of any kind arising out of any inaccuracies contained in this material
or due to its application or use in any product or circuit and, further, there is no representation that this material
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All other product names mentioned herein are trademarks and/or registered trademarks of their respective
companies.
©SEIKO EPSON CORPORATION 2008, All rights reserved.
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Configuration of product number
DEVICES
S1 F 76680 F 5A1 00B

Packing specifications
Specifications
Shape
(F:QFN)
Model number
Model name
(F : Power Supply)
Product classification
(S1:Semiconductors)
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S1F76680 Technical Manual (Rev.1.22) EPSON i
Table of Contents
1. DESCRIPTION ................................................................................................................1
2. FEATURES......................................................................................................................1
3. BLOCK DIAGRAM ..........................................................................................................2
4. DESCRIPTION OF BLOCK DIAGRAM...........................................................................3
5. PIN ASSIGNMENT ..........................................................................................................4
6. PIN DESCRIPTION .........................................................................................................5
7. OPERATIONAL AND FUNCTIONAL DESCRIPTION.....................................................7
7.1 Activation sequence .....................................................................................................................7
7.2 Setting and operating state..........................................................................................................8
7.3 LED current setting.......................................................................................................................8
7.3.1 Setting of maximum current value ............................................................................................8
7.3.2 Setting of automatic luminance control.....................................................................................9
7.4 I2C slave function........................................................................................................................17
7.5 Other functions ...........................................................................................................................19
8. ABSOLUTE MAXIMUM RATINGS ................................................................................20
9. ELECTRICAL CHARACTERISTICS .............................................................................21
10. EXTERNAL CONNECTION DIAGRAM ......................................................................22
10.1 Standard Connection Examples ..............................................................................................22
10.2 Recommended connection parts.............................................................................................23
<Precautions> ..................................................................................................................24
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1. DESCRIPTION
S1F76680 Technical Manual (Rev.1.22) EPSON 1
1. DESCRIPTION
S1F76680 is a LED driver that can drive four (three) white LEDs lamps for backlighting in parallel
connection.
Necessary power is supplied to LED by the charge pump type DC/DC converter incorporated in S1F76680.
Also, the charge pump type DC/DC converter selects 1x or1.5x voltages on its own according to necessity.
Maximum driving current to LED can be set with one external resistor.
With S1F76680, LED’s current value is changed in harmony with ambient brightness level, when connected
with an external luminance sensor.
In this IC, a two-wire serial interface I2C-Bus slave function is contained, and the current value in accordance
with the ambient brightness can be set with a register of I2C.
Allowing to configure the backlight that automatically selects optimal LED current value in accordance with
thebrightness level of the surrounding environment, this function makes this device a optimal LED driver for
mobile devices realizing high viewability and low power consumption.
2. FEATURES
zDrives four (three) white LEDs lamps in parallel connection
zSets LED maximum current value with an external resistor
zPower saving operation due to booster magnification automatic switching function of an amp circuit
zDriving with the LED current value changed in accordance to the ambient brightness level (automatic
luminance control) when connected with a luminance sensor
zAllows setting of the automatic luminance control characteristic with I2C
zEnable automatic luminance control/imperative fixed current selection with I2C
zAcquires the information on ambient brightness with I2C
zIncorporates a soft start circuit for activation with EN1 pin
zEnable automatic luminance control circuit activation/stop selection with EN2 pin
zAllows a drive at set maximum current with EN3 pin
zMass production form QFN5-32PIN (5.0mm ×5.0mm)
zNot radiation- or light-proofed
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3. BLOCK DIAGRAM
2 EPSON S1F76680 Technical Manual (Rev.1.22)
3. BLOCK DIAGRAM
S1F76680
Charge pump
Automatic
luminance
control
I
2
C-Bus serial
interface
LED drive
r
VOUT
CVOUT
LED4
LED3
VSS3
LED2
LED1
AOUT
RLED
CLED
CLED
VREF
CVREF
EN1
EN2
EN3
VDD1
VSS1
CVDD
C1P
C1N
C2P
C2N
C1
C2
VDD2
VSS2
Sensor
PDOUT
RPD
PD
CPD
SAMPL
VDDL
CVDDL
SCL
SDA
RESET
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4. DESCRIPTION OF BLOCK DIAGRAM
S1F76680 Technical Manual (Rev.1.22) EPSON 3
4. DESCRIPTION OF BLOCK DIAGRAM
(1) Charge pump
The charge pump is a circuit that generates voltage required for driving LED at VOUT pin.
As a pump-up capacitor required to operate the DC/DC converter, connect capacitors C1 and C2 with
C1P, C1N, C2P and C2N pins respectively.
Connect CVOUT as a storage capacitor for booster voltage generated at VOUT pin.
(2) Automatic luminance control
A circuit that determines the LED current value in accordance with the ambient brightness.
The ambient brightness can be evaluated by connecting a luminance sensor between PD pin and VSS
(GND), and an external resistor between PDOUT pin and PD pin.
(3) I2C -Bus serial interface
Advanced setting to this IC (selection of automatic luminance control operating status, characteristic
setting, reading of brightness information, etc) can be performed externally by reading /writing an
assigned register.
Since I2C on this IC only has slave function, control should be carried out externally by the master
function.
(4) LED driver
The LED driver drives four (three) white LEDs lamps in parallel connection.
Connect it with RLED, a resistor for maximum current setting.
The LED driver drives LED based on the settings of I2C, automatic luminance control and RLED.
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5. PIN ASSIGNMENT
4 EPSON S1F76680 Technical Manual (Rev.1.22)
5. PIN ASSIGNMENT
(QFN5-32PIN)
PIN No.
Pin Name I/O QFN5-32 Function
(test) - 1 *Since this is a test pin, be sure to keep it “OPEN.”
(test) - 2 *Since this is a test pin, be sure to keep it “OPEN.”
(test) - 3 *Since this is a test pin, be sure to keep it “OPEN.”
EN3 I 4 Automatic luminance control/forced full lighting select pin. It is pulled down Internally.
VSS2 - 5 Ground pin.
(test) - 6 *Since this is a test pin, be sure to keep it “OPEN.”
VDDL I 7 Input power supply pin for I2C I/O.
EN2 I 8 Automatic luminance control circuit activation/stop select pin. It is pulled down internally.
SCL I 9 I2C clock input pin.
SDA I/O 10 I2C data I/O pin.
RESET I 11 I2C reset (register initialization) pin
SAMPL I 12 Brightness evaluation sampling cycle select pin. It is pulled up internally.
VDD2 - 13 Input power supply pin.
PD I 14 Sensor connect pin.
PDOUT O 15 Sense resistor connect pin.
CLED O 16 Pin that connects to capacitor for LED current change delay
EN1 I 17 Input pin for activating IC. It is pulled down internally.
VREF O 18 Internal reference voltage pin.
AOUT O 19 Pin that connects to resistor for LED maximum current setting.
LED1 I 20 LED1 connect pin.
LED2 I 21 LED2 connect pin.
VSS3 - 22 Ground pin.
LED3 I 23 LED3 connect pin.
LED4 I 24
LED4 connect pin. *Be sure to connect this pin to ground when using three LEDs only.
(test) - 25 *Since this is a test pin, be sure to keep it “OPEN.”
VSS1 - 26 Ground pin.
C1N - 27 Pump-up capacitor C1 connect pin.
C1P - 28 Pump-up capacitor C1 connect pin.
VOUT O 29 LED drive voltage output pin (LED common anode)
C2P - 30 Pump-up capacitor C2 connect pin.
C2N - 31 Pump-up capacitor C2 connect pin.
VDD1 - 32 Input power supply pin.
* EXPOSED DIE ATTACH PAD (refer to the outline drawing in No.P28) in the rear surface metal part of QFN5-32 package is
grounded to the same potential as VSS1=VSS2=VSS3.
Set the rear surface metal part to the open or grounding.
9 16
1
8
32 25
17
24
(test)
(test)
(test)
EN3
VSS2
(test)
VDDL
EN2
SD
A
RESET SAMPL VDD2
PD PDOUT
CLED
LED4
LED3
VSS3
LED2
LED1
A
OUT
VREF
EN1
VDD1
C2N
C2P
VOUT
C1P
C1N
VSS1
(
test
)
S1F76680
SCL
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6. PIN DESCRIPTION
S1F76680 Technical Manual (Rev.1.22) EPSON 5
6. PIN DESCRIPTION
(1) Power Supply Pin
Pin Name PIN No.
(QFN5-32) Function
VDD1
VDD2
32
13
Power supply pin.
Supply voltage that obtains VDD1 = VDD2 ≥VDDL.
Since VDD1 is a power supply pin for the charge pump circuit, connect a bypass
capacitor CVDD immediately next to the VDD1 pin.
VDDL 7 Power supply pin for I2C I/O signal interface.
Supply voltage that obtains VDD1 = VDD2 ≥VDDL.
Connect a bypass capacitor CVDDL immediately next to VDDL pin.
VSS1
VSS2
VSS3
26
5
22
Ground pin.
(2) Input pin
1
Pin Name PIN No.
(QFN5-32) Function
EN1 17 Input pin for activating IC. It is pulled down internally.
This IC is set to the standby mode as EN1=L is selected.Whenever starting this IC
from the standby mode, change the state of EN1 from L to H. When EN1=L, too, also
allows input to and output from I2C circuit.The standby current value depends on the
setting of the EN2 pin to be described later or I2C register (SEN2). (See
No.P22)Setting of EN2 (SEN)-L, in which the standby current value is reduce, is
recommended for the standby mode.
EN1 (with pull-down) Function
L Standby state
H Circuit operating state
EN2 8 Input pin that selects activation/stop state for the automatic luminance control circuit.
It is pulled down internally.
The automatic luminance control circuit operates based on the setting of this EN2 pin
or that of I2C register (SEN2), which will be explained later.
If you do not select the operating state of the automatic luminance control circuit with
the EN2 pin, fix EN2 pin to LOW, and select the operating state with I2C register
(SEN2).
EN2 (with pull-down) Function
L Automatic luminance control circuit stop state
H Automatic luminance control circuit activated state
EN3 4 Forced full lighting select pin.
It is pulled down internally.
Fix EN3 pin to LOW when activating automatic luminance control.
If EN3 pin is fixed to HIGH, LED will light at maximum luminance regardless of the
setting of EN2.
EN3 (with pull-down) Function
L Automatic luminance control mode
H Forced full lighting mode
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6. PIN DESCRIPTION
6 EPSON S1F76680 Technical Manual (Rev.1.22)
(3) Input pin
2
Pin Name PIN No.
(QFN5-32) Function
SCL 9 I2C clock input pin.
SDA 10 I2C data input pin.
RESET 11 I2C register hard reset pin.
Cancel the reset after VDDL has risen.
RESET Function
L Resets I2C register
H Exits reset
SAMPL 12 Brightness evaluation sampling cycle select pin.
This pin is pulled up to VDD1=VDD2 level in the IC.
SAMPLE (with pull-up) Sampling cycle (TSAMPL)
H 655msec
L 1310msec
(4) Pin for charge pump circuit
Pin Name PIN No.
(QFN5-32) Function
C1N
C1P
27
28
Pump-up capacitor C1 connect pin.
Pump-up capacitor C1 connect pin.
C2N
C2P
31
30
Pump-up capacitor C2 connect pin.
Pump-up capacitor C2 connect pin.
VOUT 29 LED drive voltage output pin (LED common anode)
(5) Automatic luminance control and LED
Pin Name PIN No.
(QFN5-32) Function
PDOUT 15 Sense resistor connect pin.
PD 14 Sensor connect pin.
CLED 16 Pin that connects to capacitor for delaying LED current change
It is possible to add delay to the LED current change waveform by connecting an
external capacitor CLED with this pin.
(Connection of CLED=1µF is recommended)
LED1
LED2
LED3
LED4
20
21
23
24
LED 1 cathode connect pin.
LED 2 cathode connect pin.
LED 3 cathode connect pin.
LED 4 cathode connect pin.
*Connect this pin to ground when using three LED lamps only.
AOUT 19 Connect pin for LED maximum current setting resistor
(6) Miscellaneous
Pin Name PIN No.
(QFN5-32) Function
VREF 18 Internal reference voltage pin.
Connect capacitor CVREF immediately next to VREF pin.
(test)
(test)
(test)
(test)
(test)
1
2
3
6
25
Test pin.
*Set it to “OPEN.”
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