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SC622A
LED Light Management Unit
POWER MANAGEMENT Features
Input supply voltage range -- 3.0V to 5.5V Charge pump modes -- 1x, 1.5x and 2x Flash LED -- 400mA max in flash mode, 250mA max continuous for spotlight Two user-configurable 100mA low-noise LDO regulators Charge pump frequency -- 250kHz I2C compatible interface -- up to 400kHz External flash control pin to sync with camera Optional 1s flash time out Automatic sleep mode (flash off ) -- IQ = 100A Low shutdown current -- 0.1A (typical) Ultra-thin package -- 3mm x 3mm x 0.6mm Fully WEEE and RoHS compliant
Charge Pump, 400mA Flash LED, Dual LDOs, and I2C Interface Description
The SC622A 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 continuous or bursted current to a flash LED using a dedicated flash driver current sink. The load and supply conditions determine whether the charge pump operates in 1x, 1.5x, or 2x mode. A flashtimeout feature disables the flash if active for longer than 1 second. The SC622A also provides two low-dropout, low-noise linear regulators for powering a camera module or other peripheral circuits. The SC622A uses an I2C compatible serial interface. The interface controls all functions of the device, including flash current and two LDO voltage outputs. The flash/ spotlight output is triggered via either the I2C interface or a dedicated pin. In sleep mode, the device reduces quiescent current to 100A while continuing to monitor the serial interface. The two LDOs can be enabled when the device is in sleep mode. Total current reduces to 0.1A in shutdown.
Applications
Cellular phone flash PDA flash Camera I/O and core power
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Typical Application Circuit
FLASH
VBAT CIN 2.2F
VIN I2C Data I2C Clock Flash Control Enable Control SDA SCL FLEN EN BYP CBYP 22nF
VOUT
SC622A
COUT 4.7F
FL AGND PGND C1+ C1 2.2F C1LDO 1 LDO 2 C2+ C2C2 2.2F CLDO1 1F VLDO1 = 2.5V to 3.3V VLDO2 = 1.5V to 1.8V CLDO2 1F
US Patents: 6,504,422; 6,794,926 July 19, 2007
(c) 2007 Semtech Corporation
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SC622A
Pin Configuration Ordering Information
Device
C1+ C2+ C1VIN VOUT
Package
MLPQ-UT-20 3x3 Evaluation Board
SC622AULTRT(1)(2) SC622AEVB
20 C2PGND FL NC NC 1 2 3 4 5 6
19
18
17
16 15 LDO1 LDO2 BYP EN SDA
TOP VIEW
Notes: (1) Available in tape and reel only. A reel contains 3,000 devices. (2) Available in lead-free package only. Device is WEEE and RoHS compliant.
14 13 12
T
11 9 10
7
8
AGND
MLPQ-UT-20; 3x3, 20 LEAD JA = 35C/W
Marking Information
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622A yyww xxxx
yyww = Date Code xxxx = Semtech Lot No.
FLEN
SCL
NC
NC
2
SC622A
Absolute Maximum Ratings
VIN (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0 VOUT (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0 C1+, C2+ (V) . . . . . . . . . . . . . . . . . . . . . . . -0.3 to (VOUT + 0.3) Pin Voltage - All Other Pins (V) . . . . . . . . . . . -0.3 to (VIN + 0.3) VOUT Short Circuit Duration . . . . . . . . . . . . . . . . Continuous VLDO1, VLDO2 Short Circuit Duration. . . . . . . Continuous ESD Protection Level(1) (kV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Thermal Resistance, Junction to Ambient(2) (C/W) . . . . 35 Maximum Junction Temperature (C) . . . . . . . . . . . . . . +150 Storage Temperature Range (C) . . . . . . . . . . . . -65 to +150 Peak IR Reflow Temperature (10s to 30s) (C) . . . . . . . +260
Exceeding the above specifications may result in permanent damage to the device or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not recommended. NOTES: (1) Tested according to JEDEC standard JESD22-A114-B. (2) Calculated from package in still air, mounted to 3" x 4.5", 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards.
Recommended Operating Conditions
Ambient Temperature Range (C) . . . . . . . . -40 < TA < +85 VIN (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 < VIN < 5.5 VOUT (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 < VOUT < 5.25
Thermal Information
Electrical Characteristics
Unless otherwise noted, TA = +25C for Typ, -40C to +85C for Min and Max, TJ(MAX) = 125C, VIN = 3.0V to 4.2V, CIN= C1= C2= 2.2F, COUT = 4.7F (ESR = 0.03)
Parameter
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Symbol
Conditions
Min
Typ
Max
Units
Supply Specifications Shutdown Current IQ(OFF) Shutdown, VIN = 4.2V Sleep (LDOs off ), EN = VIN Sleep (LDOs on), EN = VIN, VIN > (VLDO + 300mV), ILDO < 200mA 0.1 100 220 3.8 4.6 4.6 2 160 A 340 4.65 5.85 5.85 mA A
Total Quiescent Current
IQ
Charge pump in 1x mode Charge pump in 1.5x mode Charge pump in 2x mode
Fault Protection Output Short Circuit Current Limit Over-Temperature Flash Mode Safety Timer(1) IOUT(SC) TOTP tFL(MAX) Flash sink active 0.75 VOUT pin shorted to GND 300 160 1.00 1.25 mA C s
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SC622A
Electrical Characteristics (continued)
Parameter
Fault Protection (continued) Charge Pump Over-Voltage Protection VOVP VUVLO Undervoltage Lockout VUVLO-HYS Charge Pump Electrical Specifications Maximum Total Output Current Flash Current Setting Flash Current Accuracy 1x Mode to 1.5x Mode Falling Transition Voltage 1.5x Mode to 2x Mode Falling Transition Voltage Current Sink Off-State Leakage Current Pump Frequency LDO Electrical Specifications LDO1 Voltage Setting VLDO1 VLDO2 VLDO1, VLDO2 Range of nominal settings in 100mV increments Range of nominal settings in 100mV increments VIN = 3.7V, ILDO = 1mA LDO1, ILDO1 = 1mA, VOUT = 2.8V Line Regulation VLINE LDO2, ILDO2 = 1mA, VOUT = 1.8V 1.3 4.8 2.5 3.3 V IOUT(MAX) IFL IFL_ACC V TRANS1x V TRANS1.5x IBLn fPUMP VIN > 3.4V, VOUT(MAX) = 4.0V Nominal setting for FL VIN = 3.7V, IFL = 400mA, TA = 25C IOUT = 100mA, VOUT = 3.3V IOUT = 100mA, VOUT = 4.5V(2) VIN = VFL = 4.2V VIN = 3.2V 400 50 -15 3.37 400 +15 mA mA % V 300 mV VOUT pin open circuit, VOUT = VOVP rising threshold Decreasing VIN 5.3 5.7 2.4 6.0 V V
Symbol
Conditions
Min
Typ
Max
Units
3.3
V
0.1 250
1
A kHz
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LDO2 Voltage Setting LDO1, LDO2 Output Voltage Accuracy
1.5
1.8
V
-3.5
3
+3.5
%
2.1
7.2 mV
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SC622A
Electrical Characteristics (continued)
Parameter Symbol Conditions Min Typ Max Units
LDO Electrical Specifications (continued) VLDO1 = 3.3V, VIN = 3.7V, ILDO1 = 1mA to 100 mA VLDO2 = 1.8V, VIN = 3.7V, ILDO2 = 1mA to 100 mA ILDO1 = 100mA 200 2.5V < VLDO1 < 3V, f < 1kHz, CBYP = 22nF, ILDO1 = 50mA, VIN = 3.7V with 0.5VP-P ripple f < 1kHz, CBYP = 22nF, ILDO2 = 50mA, VIN = 3.7V with 0.5VP-P ripple LDO1, 10Hz < f < 100kHz, CBYP = 22nF, CLDO = 1F, ILDO1 = 50 mA, VIN = 3.7V, 2.5V < VLDO1 < 3V LDO2, 10Hz < f < 100kHz, CBYP = 22nF, CLDO = 1F, ILDO2 = 50 mA, VIN = 3.7V 50 dB 60 100 25 mV 20 150 mV mA
Load Regulation
VLOAD
Dropout Voltage(3) Current Limit
VD ILIM PSRRLDO1 PSRRLDO2 en-LDO1
Power Supply Rejection Ratio
100 VRMS 50 1 F
Output Voltage Noise en-LDO2 Minimum Output Capacitor CLDO(MIN)
Digital I/O Electrical Specifications (FLEN, EN) Input High Threshold Input Low Threshold Input High Current www..com Input Low Current VIH VIL IIH IIL VIN = 5.5V VIN = 3.0V VIN = 5.5V VIN = 5.5V -1 -1 1.6 0.4 +1 +1 V V A A
I2C Interface
Interface complies with slave mode I2C interface as described by Philips I2C specification version 2.1 dated January, 2000. VB-IL Digital Input Voltage VB-IH SDA Output Low Level Digital Input Current Hysteresis of Schmitt Trigger Inputs Maximum Glitch Pulse Rejection IB-IN VHYS tSP IDIN (SDA) 3mA -0.2 0.1 1.6 0.4 0.2 V V A V 0.4 V
50
ns
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SC622A
Electrical Characteristics (continued)
Parameter
I2C Interface (continued) I/O Pin Capacitance I2C Timing Clock Frequency SCL Low Period(4) SCL High Period(4) Data Hold Time(4) Data Setup Time(4) Setup Time for Repeated START Condition(4) Hold Time for Repeated START Condition(4) Setup Time for STOP Condition(4) Bus-Free Time Between STOP and START(4) Interface Start-up Time(4) Notes: (1) Once tripped, flash output will remain disabled until FLEN pin is cycled or reset via serial interface. www..com (2) Test voltage is VOUT = 4.5V -- a relatively extreme LED voltage -- to force a transition during test. Typically VOUT = 3.3V for the white LED at 100mA. (3) Dropout is defined as (VIN - VLDO1) when VLDO1 drops 100mV from nominal. Dropout does not apply to LDO2 since it has a maximum output voltage of 1.8V. (4) Guaranteed by design fSCL tLOW tHIGH tHD_DAT tSU_DAT tSU_STA tHD_STA tSU_STO tBUF tEN Bus Start-up Time After EN Pin is Pulled High 1.3 0.6 0 100 0.6 400 440 kHz s s s s s CIN 10 pF
Symbol
Conditions
Min
Typ
Max
Units
0.6
s
0.6
s
1.3
s
1
ms
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SC622A
Typical Characteristics
Battery Current -- 250mA Spotlight
450 VOUT=3.47V, IOUT=250mA, 25C
100
Efficiency -- 250mA Spotlight
VOUT=3.47V, IOUT=250mA, 25C
400 Battery Current (mA)
90
% Efficiency
350
80
300
70
250
60
200 4.2
4
3.8
3.6 VIN (V)
3.4
3.2
3
50 4.2
4.0
3.8
3.6 VIN (V)
3.4
3.2
3.0
Battery Current -- 100mA Spotlight
180 VOUT=3.22V, IOUT=100mA, 25C 100
Efficiency -- 100mA Spotlight
VOUT=3.22V, IOUT=100mA, 25C
160
Battery Current (mA)
90
% Efficiency
140
80
120
70
100
60
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80 4.2 4 3.8 3.6 VIN (V) 3.4 3.2 3
50 4.2
4
3.8
3.6 VIN (V)
3.4
3.2
3
Battery Current -- 50mA Spotlight
65 VOUT=3.0V, IOUT=50mA, 25C
100
Efficiency -- 50mA Spotlight
VOUT=3.0V, IOUT=50mA, 25C
60
90
Battery Current (mA)
% Efficiency
55
80
50
70
45
60
40 4.2
4
3.8
3.6 VIN (V)
3.4
3.2
3
50 4.2
4
3.8
3.6 VIN (V)
3.4
3.2
3
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SC622A
Typical Characteristics (continued)
Flash Current -- 300mA
390 VOUT=3.58V at 25C
490
Flash Current -- 400mA
VOUT=3.39V at 25C
360
460
Flash Current (mA)
330
Flash Current (mA)
430
300
400
270
370
240
340 310 4.2
210 4.2
4.0
3.8
3.6 VIN (V)
3.4
3.2
3.0
4.0
3.8
3.6 VIN (V)
3.4
3.2
3.0
Spotlight Current -- 50mA
53 VOUT=3.02V at 25C
340
Spotlight Current -- 250mA
VOUT=3.50V at 25C
52
Spotlight Current (mA)
Spotlight Current (mA)
310
51
280
50
250
49
220
48
190 160 4.2
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47 4.2 4.0 3.8 3.6 VIN (V) 3.4 3.2 3.0
4.0
3.8
3.6 VIN (V)
3.4
3.2
3.0
PSRR vs. Frequency (LDO1)
0 -10 -20
PSRR (dB)
PSRR vs. Frequency (LDO2)
0 -10 -20
PSRR (dB)
VIN=3.7V at 25C, ILDO1=50mA, VLDO1=2.8V
VIN=3.7V at 25C, ILDO2=50mA, VLDO2=1.8V
-30 -40 -50 -60 -70 10 100 Frequency (Hz) 1000 10000
-30 -40 -50 -60 -70 10
100
Frequency (Hz)
1000
10000
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SC622A
Typical Characteristics (continued)
Load Regulation (LDO1)
24 VLDO1=3.3V, VIN=3.7V, 25C
Load Regulation (LDO2)
24 VLDO2=1.8V, VIN=3.7V, 25C
16
Output Voltage Variation (mV)
16
Output Voltage Variation (mV)
8
8
0
0
-8
-8
-16 -24 0 30 60 ILDO1(mA) 90 120 150
-16 -24 0 30 60 ILDO2(mA) 90 120 150
Noise vs Load Current (LDO1)
100 VLDO1=2.8V, VIN=3.7V, 25C 100
Noise vs Load Current (LDO2)
VLDO2=1.8V, VIN=3.7V, 25C
90
80
Noise (V)
70
Noise (V)
80
60
40
60
20
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50 0 20 40 ILDO1 (mA) 60 80 100 0 0 20 40 ILDO2 (mA) 60 80 100
Line Regulation (LDO1)
2 VLDO1=2.8V, ILDO1=1mA, 25C
2
Line Regulation (LDO2)
VLDO2=1.8V, ILDO2=1mA, 25C
Output Voltage Variation (mV)
0
Output Voltage Variation (mV)
1
1
0
-1
-1
-2
-2
-3 4.2
4.0
3.8
3.6 VIN (V)
3.4
3.2
3.0
-3 4.2 4.0 3.8 3.6 VIN (V) 3.4 3.2 3.0
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SC622A
Typical Characteristics (continued)
Load Transient Response (LDO1) -- Rising Edge
VIN=3.7V, VLDO1=2.8V, ILDO1=1 to 100mA
Load Transient Response (LDO2) -- Rising Edge
VIN=3.7V, VLDO2=1.8V, ILDO2=1 to 100mA
VLDO1 (50mV/div) VLDO2 (50mV/div)
ILDO1 (100mA/div)
ILDO2 (100mA/div)
Time (20s/div)
Time (20s/div)
Load Transient Response (LDO1) -- Falling Edge
VIN=3.7V, VLDO1=2.8V, ILDO1=100 to 1mA
Load Transient Response (LDO2) -- Falling Edge
VIN=3.7V, VLDO2=1.8V, ILDO2=100 to 1mA
VLDO1 (50mV/div) VLDO2 (50mV/div)
ILDO1 (100mA/div)
ILDO2 (100mA/div)
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Time (200s/div) Time (200s/div)
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SC622A
Typical Characteristics (continued)
Output Short Circuit Current Limit
VOUT=0V, VIN=4.2V, 25C VFLEN (5V/div) VOUT (1V/div) VOUT (2V/div)
Flash Mode Safety Timer
VIN=3.7V, 25C
IOUT (100mA/div)
IFL (200mA/div)
Time (1ms/div)
Time (200ms/div)
Output Open Circuit Protection
VIN=3.7V, 25C VFL (500mV/div) 6V VOUT (2V/div) VFLEN (5V/div)
Flash Current Pulse
IFL=400mA, VIN=3.7V, VOUT=3.7V, 25C
VOUT (2V/div)
0V IFL (100mA/div) IFL (200mA/div)
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Time (200s/div) Time (40ms/div)
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SC622A
Pin Descriptions
Pin #
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
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Pin Name
C2PGND FL NC NC NC NC AGND SCL FLEN SDA EN BYP LDO2 LDO1 VOUT C2+ C1+ VIN C1THERMAL PAD
Pin Function
Negative connection to bucket capacitor 2 -- requires a 2.2F capacitor connected to C2+ Ground pin for high current charge pump and Flash LED driver Current sink output for flash LED(s) Unused pin -- do not terminate Unused pin -- do not terminate Unused pin -- do not terminate Unused pin -- do not terminate Analog ground pin -- connect to ground and separate from PGND current I2C clock input pin Control pin for flash LED(s) -- high = ON, low = OFF I2C bi-directional data pin -- used for read and write operations for all internal registers (refer to Register Map and I2C Interface sections) Chip enable -- active high -- low state resets all registers (see register map table) Bypass pin for voltage reference -- connect with a 22nF capacitor to AGND Output of LDO2 -- connect with a 1F capacitor to AGND Output of LDO1 -- connect with a 1F capacitor to AGND Charge pump output -- all LED anode pins should be connected to this pin -- requires a 4.7F capacitor to PGND Positive connection to bucket capacitor 2 -- requires a 2.2F capacitor connected to C2Positive connection to bucket capacitor 1 -- requires a 2.2F capacitor connected to C1Battery voltage input -- connect with a 2.2F capacitor to PGND Negative connection to bucket capacitor 1 -- requires a 2.2F capacitor connected to C1+ Thermal pad for heatsinking purposes -- connect to ground plane using multiple vias -- not connected internally
16 17 18 19 20 T
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SC622A
Block Diagram
C1+ 18
C120
C2+ 17
C21 VOUT
VIN
19
VIN
mAhXLifeTM Fractional Charge Pump (1x, 1.5x, 2x)
16 2
VOUT PGND
EN SDA FLEN SCL
12 11 10 9 I2 C Compatible Interface and Logic Control Oscillator 4 5 6 Current Setting DAC 7 3 NC NC NC NC FL
BYP
13
Bandgap Reference
Voltage Setting DAC
VIN
LDO1
15
LDO1
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VIN
LDO2 AGND 8
14
LDO2
13
SC622A
Applications Information
General Description
This design is optimized for handheld applications supplied from a single Li-Ion cell and includes the following key features: connected between the C2+ and C2- pins as shown in the typical application circuit diagram. These capacitors should be equal in value, with a minimum capacitance of 2.2F to support the charge pump current requirements. The device also requires a 2.2F capacitor on the VIN pin and a 4.7F capacitor on the VOUT pin to minimize noise and support the output drive requirements. Capacitors with X7R or X5R ceramic dielectric are strongly recommended for their low ESR and superior temperature and voltage characteristics. Y5V capacitors should not be used as their temperature coefficients make them unsuitable for this application.
* * * *
A high efficiency fractional charge pump that supplies power to the flash LED An LED flash output that provides up to 400mA of momentary current or up to 250mA of continuous spotlight current Two adjustable LDOs with outputs ranging from 2.5V to 3.3V for LDO1 and 1.5V to 1.8V for LDO2, adjustable in 100mV increments An I2C compatible interface that provides control of all device functions
LED Flash and Spotlight Current Sink
A single output current sink is provided to drive both flash and spotlight functions. In flash mode, this current sink provides up to 400mA for a flash LED or array of parallel LEDs. Flash current settings are in 50mA increments from 50mA to 400mA. The FLEN pin directly triggers the FLASH function when pulled high, or it can be wired to VIN to enable software control via the serial interface. In spotlight mode, the output can be set for up to 250mA of continuous current. Settings are available in 50mA increments from 50mA to 250mA. Continuous operation above 250mA is not recommended due to high power dissipation.
High Current Fractional Charge Pump
The flash output is supported by a high efficiency, high current fractional charge pump output at the VOUT pin. The charge pump multiplies the input voltage by 1, 1.5, or 2 times. The charge pump switches at a fixed frequency of 250kHz in 1.5x and 2x modes and is disabled in 1x mode to save power and improve efficiency. The mode selection circuit automatically selects the 1x, 1.5x or 2x mode based on circuit conditions. Circuit conditions such as low input voltage, high output current, www..com or high LED voltage place a higher demand on the charge pump output. A higher numerical mode may be needed momentarily to maintain regulation at the VOUT pin during intervals of high demand, such as the high current of an LED flash or the droop at the VIN pin during a supply voltage transient. The charge pump responds to these momentary high demands, setting the charge pump to the optimum mode (1x, 1.5x or 2x), as needed to deliver the output voltage and load current while optimizing efficiency. Hysteresis is provided to prevent mode toggling. The charge pump requires two bucket capacitors for low ripple operation. One capacitor must be connected between the C1+ and C1- pins and the other must be
Flash and Spotlight Safety Timer
A safety timer disables the flash and spotlight output current sink if the sink remains active for an extended period. The timer protects the SC622A and the LED from high power dissipation that can cause overheating. The timer's default state is on, but the timer may be disabled via the serial interface to allow continuous output current in spotlight mode. The safety timer affects only the FL pin and will turn off the sink after a period of 1 second. The timer may be reset by either forcing the FLEN pin low or by resetting the Flash/Spotlight control bits via the interface.
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SC622A
Applications Information (continued)
Programmable LDO Outputs
Two low dropout (LDO) regulators are provided for camera module I/O and core power. Each LDO has at least 100mA of available load current with 3.5% accuracy. The minimum current limit is 200mA, so outputs greater than 100mA are possible at somewhat reduced accuracy. A 1F, low ESR capacitor should be used as a bypass capacitor on each LDO output to reduce noise and ensure stability. In addition, it is recommended that a minimum 22nF capacitor be connected from the BYP pin to ground to minimize noise and achieve optimum power supply rejection. A larger capacitor can be used for this function, but at the expense of increasing turnon time. Capacitors with X7R or X5R ceramic dielectric are strongly recommended for their low ESR and superior temperature and voltage characteristics. Y5V capacitors should not be used as their temperature coefficients make them unsuitable for this application.
Protection Features
The SC622A provides several protection features to safeguard the device from catastrophic failures. These features include:
* * * * *
Output Open Circuit Protection Over-Temperature Protection Charge Pump Output Current Limit LDO Current Limit LED Float Detection
Shutdown State
The device is disabled when the EN pin is low. All registers are reset to default condition when EN is low.
Output Open Circuit Protection Over-Voltage Protection (OVP) is provided at the VOUT pin to prevent the charge pump from producing an excessively high output voltage. In the event of an open circuit at VOUT, the charge pump runs in open loop and the voltage rises up to the OVP limit. OVP operation is hysteretic, meaning the charge pump will momentarily turn off until VOUT is sufficiently reduced. The maximum OVP threshold is 6.0V, allowing the use of a ceramic output capacitor rated at 6.3V with no fear of over-voltage damage. Over-Temperature Protection The Over-Temperature (OT) protection circuit helps prevent the device from overheating and experiencing a catastrophic failure. When the junction temperature exceeds 160C, the device goes into thermal shutdown with all outputs disabled until the junction temperature is reduced. All register information is retained during thermal shutdown.
Sleep Mode
When the LED is off, sleep mode is activated. This is a reduced current mode that helps minimize overall current www..com consumption by turning off the clock and the charge pump while continuing to monitor the serial interface for commands. Both LDOs can be powered up while in sleep mode.
I2C Compatible Interface Functions
All device functions can be controlled via the I2C compatible interface. The interface is described in detail in the Serial Interface section of the datasheet.
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SC622A
Applications Information (continued)
Charge Pump Output Current Limit The device also limits the charge pump current at the VOUT pin. When VOUT is shorted to ground, the typical output current is 300mA. The current limiting is triggered by an output under-voltage lockout below 2V. The output returns to normal when the short is removed and VOUT is above 2.5V. Above 2.5V, a typical current limit of 1A applies. LDO Current Limit The device limits the output currents of LDO1 and LDO2 to help prevent it from overheating and to protect the loads. The minimum limit is 200mA, so load current greater than the rated 100mA can be used with degraded accuracy and larger dropout without tripping the current limit. LED Float Detection Float detect is a fault detection feature of the LED current sink output. If the output is programmed to be enabled and an open circuit fault occurs the current sink output, the output will be disabled to prevent a sustained output OVP condition from occurring due to the resulting open loop.
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SC622A
Applications Information (continued)
PCB Layout Considerations
The layout diagram in Figure 1 illustrates a proper two-layer PCB layout for the SC622A and supporting components. Following fundamental layout rules is critical for achieving the performance specified in the Electrical Characteristics table. The following guidelines are recommended when developing a PCB layout:
* *
* *
*
Place all bypass and decoupling capacitors -- C1, C2, CIN, COUT, CLDO1, CLDO2, and CBYP as close to the device as possible. All charge pump current passes through VIN, VOUT, and the bucket capacitor connection pins. Ensure that all connections to these pins make use of wide traces so that the resistive drop on each connection is minimized. The thermal pad should be connected to the ground plane using multiple vias to ensure proper thermal connection for optimal heat transfer.
*
*
Make all ground connections to a solid ground plane as shown in the example layout (Figure 3). If a ground layer is not feasible, the following groupings should be connected: PGND -- CIN, COUT AGND -- Ground Pad, CLDO1, CLDO2, CBYP If no ground plane is available, PGND and AGND should be routed back to the negative battery terminal as separate signals using thick traces. Joining the two ground returns at the terminal prevents large pulsed return currents from mixing with the low-noise return currents of the LDOs. Both LDO output traces should be made as wide as possible to minimize resistive losses.
GND
CIN
C1
C2
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VOUT C1+ C2+ VIN C1-
VOUT
COUT
CLDO1
LDO1
C2-
VIN
GND
PGND
LDO2
CLDO2
Figure 2 -- Layer 1
FL
SC622A
BYP
NC
EN
CBYP
NC SDA
AGND
NC
Figure 1 -- Recommended PCB Layout
NC
FLEN
SCL
Figure 3 -- Layer 2
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SC622A
Register Map
Address
0x02 0x03
D7
0(1) 0(1)
D6
0(1) LDO2_2
D5
0(1) LDO2_1
D4
FLTO LDO2_0
D3
FL_2 LDO1_3
D2
FL_1 LDO1_2
D1
FL_0 LDO1_1
D0
FL/SPLB LDO1_0
Reset Value
0x10 0x00
Description
Flash/Spotlight Control LDO Control
Notes: (1) 0 = always write a 0 to these bits
Register and Bit Definitions
Flash/Spotlight Control Register (0x02) This register is used to configure the flash time-out feature, the flash or spotlight current, and select flash or spotlight current ranges. FLTO This bit is used to enable the flash safety time-out feature. The default state is enabled with FLTO = 1. If this bit is set, the device will turn off the flash after a nominal period of 1s. Two ways to re-enable the flash function after a safety time-out are: Pull the FLEN pin low to re-enable the flash function Clear and re-write FL[2:0]
FL_2
0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1
Table 1 -- Flash/Spotlight Control Bits
FL_1
0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1
FL_0
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
FL/ SPLB
0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1
Flash/Spotlight Current (mA)
OFF 50 100 150 200 250 250 250 OFF 300(1) 350(1) 400(1) 400(1) 400(1) 400(1) 400(1)
* *
FL[2:0] These bits are used to set the current for the flash current www..com sink when configured for flash or spotlight by the FL/ SPLB bit. Bits FL[2:0] set the flash or spotlight current, as shown in Table 1.
Note: (1) When on continuously, the device may reach the temperature limit with 300mA and higher.
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SC622A
Register and Bit Definitions (continued)
FL/SPLB This bit is used to select either the flash or spotlight current ranges. If this bit is set, the FL current sink can be used to drive a flash of maximum duration 500ms and the current range will be the high (flash) current range. If this bit is cleared, the FL current sink can be used to drive a continuous spotlight at a lower current and the current range will be the lower (spotlight) current range, as shown in Table 1. LDO Control Register (0x03) This register is used to enable the LDOs and to set their output voltages. LDO2[2:0] These bits are used to set the output voltage of LDO2, as shown in Table 2. Table 2 -- LDO2 Control Bits
LDO2_2
0 0 0 0
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LDO1[3:0] These bits set the output voltage of LDO1, as shown in Table 3. Table 3 -- LDO1 Control Bits
LDO1_3
0 0 0 0 0 0 0 0 1 1
LDO1_2
0 0 0 0 1 1 1 1 0 0
LDO1_1
0 0 1 1 0 0 1 1 0 0
LDO1_0
0 1 0 1 0 1 0 1 0 1
LDO1 Output Voltage
OFF 3.3V 3.2V 3.1V 3.0V 2.9V 2.8V 2.7V 2.6V 2.5V OFF
LDO2_1
0 0 1 1 0
LDO2_0
0 1 0 1 0
LDO2 Output Voltage
OFF 1.8V 1.7V 1.6V 1.5V OFF
1010 through 1111 are not used
1
101 through 111 are not used
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SC622A
Serial Interface
The I2C General Specification
The SC622A is a read-write slave-mode I C device and complies with the Philips I2C standard Version 2.1, dated January 2000. The SC622A has four user-accessible internal 8-bit registers. The I2C interface has been designed for program flexibility, supporting direct format for write operation. Read operations are supported on both combined format and stop separated format. While there is no auto increment/decrement capability in the SC622A I2C logic, a tight software loop can be designed to randomly access the next register independent of which register you begin accessing. The start and stop commands frame the data-packet and the repeat start condition is allowed if necessary.
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by an eighth bit indicating a write. The SC622A I2C then acknowledges that it is being addressed, and the master responds with an 8 bit data byte consisting of the register address. The slave acknowledges and the master sends the appropriate 8 bit data byte. Once again the slave acknowledges and the master terminates the transfer with the stop condition [P]. Combined Format -- Read After the start condition [S], the slave address is sent, followed by an eighth bit indicating a write. The SC622A I2C then acknowledges that it is being addressed, and the master responds with an 8 bit data byte consisting of the register address. The slave acknowledges and the master sends the repeated start condition [Sr]. Once again, the slave address is sent, followed by an eighth bit indicating a read. The slave responds with an acknowledge and the previously addressed 8 bit data byte; the master then sends a non-acknowledge (NACK). Finally, the master terminates the transfer with the stop condition [P]. Stop Separated Reads Stop-separated reads can also be used. This format allows a master to set up the register address pointer for a read and return to that slave at a later time to read the data. In this format the slave address followed by a write command are sent after a start [S] condition. The SC622A then acknowledges it is being addressed, and the master responds with the 8-bit register address. The master sends a stop or restart condition and may then address another slave. After performing other tasks, the master can send a start or restart condition to the SC622A with a read command. The device acknowledges this request and returns the data from the register location that had previously been set up.
SC622A Limitations to the I2C Specifications
The SC622A only recognizes seven bit addressing. This means that ten bit addressing and CBUS communication are not compatible. The device can operate in either standard mode (100kbit/s) or fast mode (400kbit/s).
Slave Address Assignment
The seven bit slave address is 0110 111x. The eighth bit is the data direction bit. 0x6E is used for a write operation, and 0x6F is used for a read operation.
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The supported formats are described in the following subsections. Direct Format -- Write The simplest format for an I2C write is direct format. After the start condition [S], the slave address is sent, followed
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SC622A
Serial Interface (continued)
I2C Direct Format Write
S Slave Address W A Register Address A Data A P
S - Start Condition W - Write = `0' A - Acknowledge (sent by slave) P - Stop condition
Slave Address - 7-bit Register address - 8-bit Data - 8-bit
I2C Stop Separated Format Read
Register Address Setup Access S Slave Address W A Register Address A P S
S - Start Condition W - Write = `0' R - Read = `1' A - Acknowledge (sent by slave) NAK - Non-Acknowledge (sent by master) Sr - Repeated Start condition P - Stop condition
Master Addresses other Slaves Slave Address B S/Sr
Register Read Access Slave Address RA Data NACK P
Slave Address - 7-bit Register address - 8-bit Data - 8-bit
I2C Combined Format Read
S Slave Address WA Register Address A Sr Slave Address R A Data NACK P
S - Start Condition W - Write = `0' R - Read = `1' A - Acknowledge (sent by slave) NAK - Non-Acknowledge (sent by master) Sr - Repeated Start condition P - Stop condition
Slave Address - 7-bit Register address - 8-bit Data - 8-bit
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SC622A
Outline Drawing -- MLPQ-UT-20 3x3
B
A
D
DIMENSIONS INCHES MILLIMETERS DIM MIN NOM MAX MIN NOM MAX
A A1 A2 b D D1 E E1 e L N aaa bbb .020 .000 .024 .002 0.50 0.00 0.60 0.05 (.006) .006 .008 .010 .114 .118 .122 .061 .067 .071 .114 .118 .122 .061 .067 .071 .016 BSC .012 .016 .020 20 .003 .004 (0.1524) 0.15 0.20 0.25 2.90 3.00 3.10 1.55 1.70 1.80 2.90 3.00 3.10 1.55 1.70 1.80 0.40 BSC 0.30 0.40 0.50 20 0.08 0.10
PIN 1 INDICATOR (LASER MARK)
E
A2 A aaa C A1 e LxN E/2 E1
2 1 N
SEATING PLANE C D1
D/2 bxN
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NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
bbb
CAB
2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS . 3. DAP is 1.90 x 190mm.
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SC622A
Land Pattern -- MLPQ-UT-20 3x3
H R DIM C G H K P R X Y Z DIMENSIONS INCHES (.114) .083 .067 .067 .016 .004 .008 .031 .146 MILLIMETERS (2.90) 2.10 1.70 1.70 0.40 0.10 0.20 0.80 3.70
(C)
K
G
Z
Y X P NOTES: 1. 2.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD SHALL BE CONNECTED TO A SYSTEM GROUND PLANE. FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR FUNCTIONAL PERFORMANCE OF THE DEVICE.
3.
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Contact Information
Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805) 498-2111 Fax: (805) 498-3804 www.semtech.com
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