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PDF SC621 Data sheet ( Hoja de datos )
| Número de pieza | SC621 | |
| Descripción | LED Light Management Unit | |
| Fabricantes | Semtech Corporation | |
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Hay una vista previa y un enlace de descarga de SC621 (archivo pdf) en la parte inferior de esta página. Total 23 Páginas | ||
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POWER MANAGEMENT
SC621
LED Light Management Unit
Charge Pump, 4 LEDs, 400mA Flash LED,
Dual LDOs, and SemWireTM Interface
Features
Description
Input supply voltage range — 3.0V to 5.5V
Charge pump modes — 1x, 1.5x and 2x
Four programmable current sinks with 32 steps from
0.5mA to 25mA
Flash LED — 400mA max in flash mode, 250mA max
continuous for spotlight
Two programmable 200mA low-noise LDO regulators
Charge pump frequency — 250kHz
SemWireTM single wire interface — up to 75kbit/s
Backlight current accuracy ±1.5% typical
Backlight current matching ±0.5% typical
Programmable fade-in/fade-out for main backlight
External flash control pin to sync with camera
Optional 1s flash time out
Automatic sleep mode (LEDs off ) — I = 100μA
Q
Low shutdown current — 0.1μA (typical)
Ultra-thin package — 3mm x 3mm x 0.6mm
Lead-free and halogen-free
WEEE and RoHS compliant
Applications
Cellular phone backlighting and flash
PDA backlighting and flash
Camera I/O and core power
The SC621 is a high efficiency charge pump LED driver
using Semtech’s proprietary mAhXLifeTM technology.
Performance is optimized for use in single-cell Li-ion
battery applications.
The charge pump provides backlight current in
conjunction with four matched current sinks. It also can
supply continuous or bursted current to a flash LED using
the dedicated flash driver current sink. The load and
supply conditions determine whether the charge pump
operates in 1x, 1.5x, or 2x mode. An optional fading feature
that gradually adjusts the backlight current is provided to
simplify control software. A flash-timeout feature disables
the flash if active for longer than 1 second. The SC621 also
provides two low-dropout, low-noise linear regulators for
powering a camera module or other peripheral circuits.
The SC621 uses the proprietary SemWireTM single wire
interface. The interface controls all functions of the
device, including backlight and flash currents as well as
two LDO voltage outputs. The single wire implementation
minimizes microcontroller and interface pin counts. The
flash/spotlight output is triggered via either the SemWire
interface or a dedicated pin.
In sleep mode, the device reduces quiescent current to
100μA while continuing to monitor the serial interface.
The two LDOs can be enabled when the device is in sleep
mode. Total current reduces to 0.1μA in shutdown.
Typical Application Circuit
VBAT
CIN
2.2μF
SemWire
Interface
Flash
Control
CBYP
22nF
VIN VOUT
SWIF
FLEN SC621
BYP
GREF
AGND
PGND
BL1
BL2
BL3
BL4
FL
LDO1
LDO2
COUT
4.7μF
MAIN BACKLIGHT
FLASH
VLDO1 = 2.5V to 3.3V
VLDO2 = 1.5V to 1.8V
C1+ C1- C2+ C2-
C1
2.2μF
C2
2.2μF
CLDO1
1μF
CLDO2
1μF
US Patents: 6,504,422; 6,794,926
October 20, 2009
© 2009 Semtech Corporation
1
1 page  
SC621
Electrical Characteristics (continued)
Parameter
Symbol
Conditions
Min Typ Max Units
LDO Electrical Specifications (continued)
Load Regulation
Dropout Voltage(5)
ΔV
LOAD
V
D
V = 3.3V, V = 3.7V,
LDO1
IN
I = 1mA to 100 mA
LDO1
V = 1.8V, V = 3.7V,
LDO2
IN
I = 1mA to 100 mA
LDO2
I = 100mA
LDO1
Current Limit
Power Supply
Rejection Ratio
Output Voltage Noise
Minimum Output Capacitor
I
LIM
PSRR
LDO1
PSRR
LDO2
e
n-LDO1
e
n-LDO2
C
LDO(MIN)
2.5V < VLDO1 < 3V, f < 1kHz, CBYP = 22nF, ILDO1 = 50mA,
V = 3.7V with 0.5V ripple
IN P-P
f < 1kHz, CBYP = 22nF, ILDO2 = 50mA,
V = 3.7V with 0.5V ripple
IN P-P
LDO1, 10Hz < f < 100kHz, CBYP = 22nF, CLDO = 1μF,
I = 50 mA, V = 3.7V, 2.5V < V < 3V
LDO1
IN
LDO1
LDO2, 10Hz < f < 100kHz, CBYP = 22nF, CLDO = 1μF,
I = 50 mA, V = 3.7V
LDO2
IN
Digital I/O Electrical Specifications (FLEN, SWIF)
200
100
50
60
100
50
1
25
mV
20
150 mV
mA
dB
μV
RMS
μF
Input High Threshold
V
IH
V = 5.5V
IN
1.6
V
Input Low Threshold
V
IL
V = 3.0V
IN
0.4 V
Input High Current
I
IH
V = 5.5V
IN
-1 +1 μA
Input Low Current
I
IL
V = 5.5V
IN
-1 +1 μA
SemWire Bit Rate
f
SWIF
10 75 kbit/s
SemWire Start-up Time(6)
tEN
1 ms
SemWire Disable Time(7)
tDIS
10 ms
SemWire Data Latch Delay(8)
D
DL
5 bit
Notes:
(1) ΔV is the voltage difference between any two LEDs.
F
(2) Once tripped, flash output will remain disabled until FLEN pin is cycled or reset via serial interface.
(3) Current matching equals ± [I - I ] / [I + I ].
BL(MAX) BL(MIN
BL(MAX) BL(MIN)
(4) Test voltage is VOUT = 4.0V — a relatively extreme LED voltage — to force a transition during test. Typically VOUT = 3.2V for white LEDs.
(5) Dropout is defined as (V -V ) whenV drops 100mV from nominal. Dropout does not apply to LDO2 since it has a maximum output voltage
IN LDO1
LDO1
of 1.8V.
(6) The SemWire start-up time is the minimum period that the SWIF pin must be held high to enable the part before commencing
communication.
(7) The SemWire disable time is the minimum period that the SWIF pin must be pulled low to shut the part down.
(8) The SemWire data latch delay is the maximum duration after communication has ended before the register is updated.
5
5 Page 
SC621
Pin Descriptions
Pin #
Pin Name
1 C2-
2 PGND
3 FL
4 BL1
5 BL2
6 BL3
7 BL4
8 AGND
9 GREF
10 FLEN
11 SWIF
12 NC
13 BYP
14 LDO2
15 LDO1
16 VOUT
17 C2+
18 C1+
19 VIN
20 C1-
T THERMAL PAD
Pin Function
Negative connection to bucket capacitor 2 — requires a 2.2μF capacitor connected to C2+
Ground pin for high current charge pump and Flash LED driver
Current sink output for flash LED(s)
Current sink output for main backlight LED 1 — leave this pin open if unused
Current sink output for main backlight LED 2 — leave this pin open if unused
Current sink output for main backlight LED 3 — leave this pin open if unused
Current sink output for main backlight LED 4 — leave this pin open if unused
Analog ground pin — connect to ground and separate from PGND current
Ground reference — connect to ground
Control pin for flash LED(s) — high = ON, low = OFF
SemWire single wire interface pin — used to enable/disable the device and to set up all internal
registers (refer to Register Map and SemWire Interface sections)
Unused pin — do not terminate
Bypass pin for voltage reference — connect with a 22nF capacitor to AGND
Output of LDO2 — connect with a 1μF capacitor to AGND
Output of LDO1 — connect with a 1μF capacitor to AGND
Charge pump output — all LED anode pins should be connected to this pin — requires a 4.7μF
capacitor to PGND
Positive connection to bucket capacitor 2 — requires a 2.2μF capacitor connected to C2-
Positive connection to bucket capacitor 1 — requires a 2.2μF capacitor connected to C1-
Battery voltage input — connect with a 2.2μF capacitor to PGND
Negative connection to bucket capacitor 1 — requires a 2.2μF capacitor connected to C1+
Thermal pad for heatsinking purposes — connect to ground plane using multiple vias — not
connected internally
11
11 Page | ||
| Páginas | Total 23 Páginas | |
| PDF Descargar | [ Datasheet SC621.PDF ] | |
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