SC628A LED Flash Driver Charge Pump with 1000mA Flash Mode, 275mA Spotlight Mode, and I2C Interface POWER MANAGEMENT Features Description The SC628A is a high efficiency charge pump LED driver using Semtech’s proprietary charge pump technology. Performance is optimized for use in single-cell Li-ion battery applications. The load and supply conditions determine whether the charge pump operates in 1x, 1.5x, or 2x mode. Input supply voltage range — 3.0V to 5.5V Charge pump modes — 1x, 1.5x and 2x Flash LED — 1000mA max in flash mode, 275mA max continuous for spotlight Charge pump frequency — 250kHz I2C compatible interface — up to 400kHz External flash control pin to sync with camera One second flash time out with disable feature Automatic sleep mode (flash off ) — IQ = 100μA Low shutdown current — 0.1μA (typical) Ultra-thin package — 3mm x 3mm x 0.6mm Fully WEEE and RoHS compliant The charge pump provides continuous spotlight mode current or pulsed flash mode current to an LED using a dedicated current sink. In flash mode, a flash-timeout feature turns off the flash if active for longer than 1 second. In spotlight mode, the timeout feature is disabled to allow continuous operation of the LED. Applications The SC628A uses an I2C compatible serial interface to set the flash mode or the spotlight mode current. The flash/ spotlight output is triggered via either the I2C interface or a dedicated flash enable pin (FLEN). Cellular phone flash PDA flash In sleep mode, the device reduces quiescent current to 100μA while continuing to monitor the serial interface. Total current reduces to 0.1μA in shutdown. Typical Application Circuit FLASH VBAT = 3.0V to 5.5V CIN 4.7μF IN OUT I2C Data SDA 2 SCL I C Clock Flash Control Enable Control SC628A COUT 4.7μF FLEN EN FL AGND PGND C1+ C1- C1 2.2μF C2+ C2- C2 2.2μF US Patents: 6,504,422; 6,794,926 July 14, 2009 1 SC628A C2- 1 PGND 2 FL IN C1+ C2+ OUT Ordering Information C1- Pin Configuration 20 19 18 17 16 15 NC 14 NC 3 13 NC NC 4 12 EN NC 5 11 SDA TOP VIEW 6 7 8 9 10 NC NC AGND SCL FLEN T Device Package SC628AULTRT(1)(2) MLPQ-UT-20 3×3 SC628AEVB Evaluation Board Notes: (1) Available in tape and reel only. A reel contains 3,000 devices. (2) Lead-free package only. Device is WEEE and RoHS compliant. MLPQ-UT-20; 3x3, 20 LEAD θJA = 40°C/W Marking Information 628A yyww xxxx yyww = Date Code xxxx = Semtech Lot No. 2 SC628A Absolute Maximum Ratings Recommended Operating Conditions IN (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0 Ambient Temperature Range (°C) . . . . . . . . -40 < TA < +85 OUT (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0 IN (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 < VIN < 5.5 C1+, C2+ (V) . . . . . . . . . . . . . . . . . . . . . . . -0.3 to (VOUT + 0.3) OUT (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 < VOUT < 5.25 Pin Voltage - All Other Pins (V) . . . . . . . . . . . -0.3 to (VIN + 0.3) OUT Short Circuit Duration . . . . . . . . . . . . . . . . . Continuous ESD Protection Level(1) (kV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Thermal Information Thermal Resistance, Junction to Ambient(2) (°C/W) . . . . 40 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. Electrical Characteristics Unless otherwise noted, TA = +25°C for Typ, -40ºC to +85°C for Min and Max, TJ(MAX) = 125ºC, VIN = 3.0V to 4.2V, CIN = COUT = 4.7μF (ESR = 0.03Ω), C1 = C2 = 2.2μF (ESR = 0.03Ω), size code 0603 (1608 metric) for all capacitors Parameter Symbol Conditions IQ(OFF) Min Typ Max Units Shutdown, VIN = 4.2V 0.1 2 μA Sleep, EN = VIN 100 160 μA Charge pump in 1x mode 3.8 4.65 Charge pump in 1.5x mode 4.6 5.85 Charge pump in 2x mode 4.6 5.85 OUT pin shorted to GND 450 mA 160 °C Supply Specifications Shutdown Current Total Quiescent Current IQ mA Fault Protection Output Short Circuit Current Limit Over-Temperature Flash Mode Safety Timer(1) Charge Pump Over-Voltage Protection IOUT(SC) TOTP tFL(MAX) Flash sink active 0.75 1.00 1.25 s VOVP OUT pin open circuit, VOUT = VOVP rising threshold 5.3 5.7 6.0 V 3 SC628A Electrical Characteristics (continued) Parameter Symbol Conditions Min Typ Max Units VUVLO Increasing VIN 2.7 V VUVLO-HYS Hysteresis 800 mV Fault Protection (continued) Undervoltage Lockout Charge Pump Electrical Specifications Maximum Total Output Current IOUT(MAX) VIN > 3.5V, VOUT(MAX) = 4.0V tFL_SET maximum time for current to settle IFL Nominal setting for FL 25 IFL_ACC VIN = 3.7V, IFL = 450mA, TA = 25°C -13 1x Mode to 1.5x Mode Falling Transition Voltage V TRANS1x IOUT = 150mA, VOUT = 3.3V 3.37 V 1.5x Mode to 2x Mode Falling Transition Voltage V TRANS1.5x IOUT = 150mA, VOUT = 4.5V(2) 3.3 V IBLn VIN = VFL = 4.2V 0.1 fPUMP VIN = 3.2V 250 Flash Current Settling Time Flash Current Setting Flash Current Accuracy Current Sink Off-State Leakage Current Pump Frequency 1000 mA 1 ±5 ms 1000 mA 13 % 1 μA kHz Digital I/O Electrical Specifications (FLEN, EN) Input High Threshold VIH VIN = 5.5V Input Low Threshold VIL VIN = 3.0V Input High Current IIH VIN = 5.5V Input Low Current IIL VIN = 5.5V 1.4 V 0.4 V -1 +1 μA -1 +1 μA 0.4 V 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 1.4 V IDIN (SDA) ≤ 3mA -0.2 0.4 V 0.2 μA Digital Input Current IB-IN Hysteresis of Schmitt Trigger Inputs VHYS 0.1 V Maximum Glitch Pulse Rejection tSP 50 ns I/O Pin Capacitance CIN 10 pF 4 SC628A Electrical Characteristics (continued) Parameter Symbol Conditions Min Typ Max Units 400 440 kHz I2C Timing Clock Frequency fSCL SCL Low Period(3) tLOW 1.3 μs SCL High Period(3) tHIGH 0.6 μs Data Hold Time(3) tHD_DAT 0 μs Data Setup Time(3) tSU_DAT 250 ns Setup Time for Repeated START Condition(3) tSU_STA 0.6 μs Hold Time for Repeated START Condition(3) tHD_STA 0.6 μs Setup Time for STOP Condition(3) tSU_STO 0.6 μs Bus-Free Time Between STOP and START(3) tBUF 1.3 μs Interface Start-up Time(3) tEN Bus Start-up Time After EN Pin is Pulled High 1 ms Notes: (1) Once tripped, flash output will remain disabled until FLEN pin is cycled or reset via serial interface. (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) Guaranteed by design 5 SC628A Typical Characteristics Spotlight Current — 25mA VOUT = 2.97V, IOUT = 25mA, TA = 25°C 31 29 440 27 420 25 400 23 380 21 360 19 4.2 3.9 3.6 VIN (V) VOUT = 3.41V, IOUT = 400mA, TA = 25°C 460 IFL (mA) IFL (mA) Flash Current — 400mA 3.3 3 340 2.7 4.2 3.9 Spotlight Current — 100mA 105 975 IFL (mA) IFL (mA) 1075 100 775 90 675 3.9 3.6 VIN (V) 3.3 3 4.2 3.9 300 1100 IFL (mA) IFL (mA) 1300 1200 275 900 225 800 200 VIN (V) 3.3 3 2.7 3 2.7 VOUT = 3.72V, IOUT = 1000mA, TA = 25°C 1000 250 3.6 3.3 Flash Current — 1000mA 325 3.9 3.6 VIN (V) VOUT = 3.32V, IOUT = 275mA, TA = 25°C 4.2 2.7 575 2.7 Spotlight Current — 275mA 350 3 875 95 4.2 3.3 VOUT = 3.69V, IOUT = 875mA, TA = 25°C 1175 110 85 VIN (V) Flash Current — 875mA VOUT = 3.14V, IOUT = 100mA, TA = 25°C 115 3.6 700 4.2 3.9 3.6 VIN (V) 3.3 3 2.7 6 SC628A Typical Characteristics (continued) Spotlight Efficiency — 275mA Spotlight Efficiency — 25mA VOUT = 2.97V, IOUT = 25mA, TA = 25°C 100 90 90 80 80 % Efficiency % Efficiency 100 70 VOUT = 3.32V, IOUT = 275mA, TA = 25°C 70 60 60 50 4.2 3.9 3.6 VIN (V) 3.3 3 50 2.7 4.2 VOUT = 3.14V, IOUT = 100mA, TA = 25°C 100 % Efficiency % Efficiency VIN (V) 3.3 3 2.7 VOUT = 3.41V, IOUT = 400mA, TA = 25°C 90 90 80 70 80 70 60 60 50 4.2 3.6 Flash Efficiency — 400mA Spotlight Efficiency — 100mA 100 3.9 3.9 3.6 VIN (V) 3.3 3 2.7 50 4.2 3.9 3.6 VIN (V) 3.3 3 2.7 7 SC628A Typical Characteristics (continued) Spotlight Mode Ripple — 1x Mode Spotlight Mode Ripple — 1.5x Mode IOUT = 275mA, TA = 25°C, Spotlight Mode IOUT = 275mA, TA = 25°C, Spotlight Mode VIN (100mVAC/div) VIN (100mVAC/div) VOUT (100mVAC/div) VOUT (100mVAC/div) IOUT (200mADC/div) IOUT (200mADC/div) 0mA— 0mA— Time (4.0μs/div) Time (4.0μs/div) Flash Mode Ripple — 1x Mode Flash Mode Ripple — 1.5x Mode IOUT = 1000mA, TA = 25°C, Flash Mode IOUT = 1000mA, TA = 25°C, Flash Mode VIN (200mVAC/div) VIN (200mVAC/div) VOUT (200mVAC/div) VOUT (200mVAC/div) IOUT (500mADC/div) 0mA— IOUT (500mADC/div) Time (4.0μs/div) 0mA— Flash Mode Ripple — 2x Mode Flash Current Pulse IOUT = 1000mA, TA = 25°C, Flash Mode VIN (200mVAC/div) Time (4.0μs/div) VIN = 3.7V, IOUT = 1000mA, TA = 25°C, tON = 100ms VFLEN (2VDC/div) 0V— VOUT (2VDC/div) VOUT (200mVAC/div) 0V— IOUT (500mADC/div) IOUT (500mADC/div) 0mA— 0mA— Time (4.0μs/div) Time (40ms/div) 8 SC628A Typical Characteristics (continued) Flash Mode Safety Timer VIN = 4.2V, IOUT = 1000mA, TA = 25°C VFLEN (2VDC/div) 0V— VOUT (2VDC/div) 0V— IOUT (500mADC/div) 0mA— Time (200ms/div) Output Open Circuit Protection VIN = 3.7V, TA = 25°C VFLEN (2VDC/div) 0V— VOUT (2VDC/div) 0V— IOUT (500mADC/div) 0mA— Time (200ms/div) Output Short Circuit Current Limit VIN = 3.7V, VOUT = 0V, TA = 25°C VFLEN (2VDC/div) 0V— VOUT (2VAC/div) 0V— IOUT (500mADC/div) 0mA— Time (200ms/div) 9 SC628A Pin Descriptions Pin # Pin Name Pin Function 1 C2- 2 PGND 3 FL Current sink output for flash LED(s) 4 NC Unused pin — do not terminate 5 NC Unused pin — do not terminate 6 NC Unused pin — do not terminate 7 NC Unused pin — do not terminate 8 AGND 9 SCL I2C clock input pin 10 FLEN Control pin for flash LED(s) — high = ON, low = OFF 11 SDA I2C bi-directional data pin — used for read and write operations for all internal registers (refer to Register Map and I2C Interface sections) 12 EN Chip enable — active high — low state resets all registers (see register map table) 13 NC Unused pin — do not terminate 14 NC Unused pin — do not terminate 15 NC Unused pin — do not terminate 16 OUT Charge pump output — all LED anode pins should be connected to this pin — requires a 4.7μF capacitor to PGND 17 C2+ Positive connection to bucket capacitor 2 — requires a 2.2μF capacitor connected to C2- 18 C1+ Positive connection to bucket capacitor 1 — requires a 2.2μF capacitor connected to C1- 19 IN Battery voltage input — connect with a 4.7μF capacitor to PGND 20 C1- Negative connection to bucket capacitor 1 — requires a 2.2μF capacitor connected to C1+ T THERMAL PAD 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 Analog ground pin — connect to ground and separate from PGND current Thermal pad for heatsinking purposes — connect to ground plane using multiple vias — not connected internally 10 SC628A Block Diagram IN 12 SDA 11 FLEN 10 SCL 9 NC C1- C2+ C2- 18 20 17 1 mAhXLifeTM Fractional Charge Pump (1x, 1.5x, 2x) 19 EN C1+ 16 OUT 2 PGND 4 NC 5 NC 6 NC 7 NC 3 FL 15 NC 14 NC Oscillator I2 C Compatible Interface and Logic Control Current Setting DAC Flash Output Current Sink 13 Bandgap Reference AGND 8 11 SC628A Applications Information General Description This design is optimized for handheld applications supplied from a single Li-Ion cell and includes the following key features: • • • A high efficiency fractional charge pump that supplies power to the flash LED An LED flash output that provides up to 1000mA of momentary current or up to 275mA of continuous spotlight current An I2C compatible interface that provides control of all device functions High Current Fractional Charge Pump The flash output is supported by a high efficiency, high current fractional charge pump output at the OUT 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, 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 OUT pin during intervals of high demand, such as the high current of an LED flash or the droop at the IN 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 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 2.2μF to support the charge pump current requirements. The device also requires a 4.7μF capacitor on the IN pin and a 4.7μF capacitor on the OUT pin to minimize noise and support the output drive requirements. Capacitor case size is an important factor in the performance of the SC628A. Due to the poor DC coefficient of the 0402 size (1005 metric), 0603 size (1608 metric) capacitors are strongly recommended to achieve the rated electrical specifications and performance shown in the typical characteristics section. 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. 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 1000mA for a flash LED or array of parallel LEDs. Flash current settings are available in 21 values from 300mA to 1000mA. Flash steps increments are no larger than 75mA nominally. Some additional settings that have smaller increments of 50mA, 25mA and 12.5mA. Table 1 on page 12 contains detailed current setting information for flash mode. The FLEN pin directly triggers the FLASH function when pulled high, or it can be wired to IN to enable software control via the serial interface. In spotlight mode, the output can be set for up to 275mA of continuous current. Settings are available in 25mA increments from 25mA to 275mA, with some additional settings that have smaller increments of 12.5mA. Table 2 on page 13 contains detailed current setting information for spotlight mode. Continuous operation above 275mA is not recommended due to high power dissipation. 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 SC628A and the LED from high power dissipation that can cause overheating. The 12 SC628A Applications Information (continued) 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. 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 160°C, the device goes into thermal shutdown with all outputs disabled until the junction temperature is reduced. All register information is retained during thermal shutdown. Shutdown State The device is disabled when the EN pin is low. All registers are reset to default condition when EN is low. Sleep Mode When the LED is off, sleep mode is activated. This is a reduced current mode that helps minimize overall current consumption by turning off the clock and the charge pump while continuing to monitor the serial interface for commands. 2 I C 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. Protection Features The SC628A provides several protection features to safeguard the device from catastrophic failures. These features include: • • • • Charge Pump Output Current Limit The device also limits the charge pump current at the OUT pin. When OUT is shorted to ground, the typical output current is 400mA. The current limiting is triggered by an output under-voltage lockout below 2V. The output returns to normal when the short is removed and OUT is above 2.5V. Above 2.5V, a minimum current limit of 1000mA applies. 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 on the current sink, the resulting open loop will cause the output voltage to change to the default condition VOUT = 3.0V. The output will remain 3.0V until the loop is once again completed by an LED or the output is re-programmed to the off state. Output Open Circuit Protection Over-Temperature Protection Charge Pump Output Current Limit LED Float Detection Output Open Circuit Protection Over-Voltage Protection (OVP) is provided at the OUT pin to prevent the charge pump from producing an excessively high output voltage. In the event of an open circuit at OUT, 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. 13 SC628A Applications Information (continued) • PCB Layout Considerations The layout diagram in Figure 1 illustrates a proper two-layer PCB layout for the SC628A 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: • OUT IN GND GND Figure 2 — Layer 1 C1+ COUT C2 C2+ C1- C1 OUT CIN C2- NC PGND NC SC628A FL NC FLEN SDA SCL EN NC NC NC AGND • IN • Place all bypass and decoupling capacitors — C1, C2, CIN, and COUT as close to the device as possible. All charge pump current passes through IN, OUT, 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. NC • • 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 If no ground plane is available, PGND and AGND should be routed back to the negative battery terminal as separate signals using thick traces. Figure 3 — Layer 2 Figure 1 — Recommended PCB Layout 14 SC628A Register Map Address 0x02 D7 D6 D5 D4 0(1) FLTO Flash/Spotlight Bits D3 D2 D1 Flash/Spotlight Bits D0 Reset Value Description 0x10 Flash/Spotlight Control Notes: (1) Always write a 0 to this bit Register and Bit Definitions Flash/Spotlight Control Register (0x02) This register is used to select the flash or spotlight current and to configure the flash time-out feature. Bits D7, D6, D3, D2, D1, D0 The value of bits D7, D6, D3, D2, D1, and D0 are used to set the current for the flash and spotlight modes. Flash current values are set in accordance with Table 1 on page 12, and spotlight current values are set in accordance with Table 2 on page 13. 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 reset the flash function Clear and re-write bits D7, D6 D3, D2, D1, and D0. • • 15 SC628A Register and Bit Definitions (continued) Table 1 — Flash Current Codes(1) Data Bits for Register 02h Flash Current 8 Bit Word D7 D6 D5 D4 D3 D2 D1 D0 IFL (mA) Hex x(2) x(2) 0(3) 1(4) 0 0 0 0 OFF 00h (3) 1 (4) 1 0 1 1 300 5Bh 1 (4) 1 1 0 1 325 5Dh 1 (4) 0 1 0 1 337.5 D5h 1 (4) 1 1 1 0 350 1Eh 1 (4) 1 0 1 0 375 9Ah 1 (4) 0 0 1 1 400 13h 1 (4) 1 0 0 1 412.5 D9h 1 (4) 0 1 0 1 450 15h 1 (4) 1 1 0 1 487.5 DDh 1 (4) 0 1 1 1 500 17h 1 (4) 1 1 1 1 525 DFh 1 (4) 1 0 0 1 550 19h 1 (4) 1 0 1 1 600 1Bh 1 (4) 1 1 0 1 650 1Dh 1 (4) 0 1 0 1 675 95h 1 (4) 1 1 1 1 700 1Fh (4) 0 0 1 0 1 0 1 0 1 0 1 0 0 0 1 0 1 1 1 0 0 0 1 0 1 0 1 0 0 0 0 0 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 1 0 0 1 0 1 1 1 750 97h 1 0 0(3) 1(4) 1 0 0 1 825 99h 1 0 0(3) 1(4) 1 0 1 1 875 9Bh 1 0 0(3) 1(4) 1 1 0 1 950 9Dh 1 0 0(3) 1(4) 1 1 1 1 1000 9Fh Notes: (1) Use only the data values shown in Table 1 for flash function. (2) Either 1 or 0. (3) Always write a 0 to this bit. (4) Write a 1 to set the FLTO bit for flash mode. 16 SC628A Register and Bit Definitions (continued) Table 2 — Spotlight Current Codes(1) Data Bits for Register 02h Spotlight Current 8 Bit Word D7 D6 D5 D4 D3 D2 D1 D0 IFL (mA) Hex x(2) x(2) 0(3) 0(4) 0 0 0 0 OFF 00h (3) (4) 0 0 1 0 25 42h (4) 0 0 1 0 37.5 C2h (4) 0 0 1 0 50 02h (4) 0 1 1 0 75 46h (4) 0 1 0 0 100 04h (4) 0 1 1 0 112.5 C6h (4) 1 0 1 0 125 4Ah (4) 0 1 1 0 150 06h (4) 1 1 1 0 175 4Eh (4) 1 0 1 0 187.5 CAh (4) 1 0 0 0 200 08h (4) 0 1 0 1 225 45h (4) 0 1 1 1 250 47h (4) 1 1 1 0 262.5 CEh (4) 1 0 0 1 275 49h 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0 1 1 0 1 0 1 1 0 1 1 0 1 1 1 1 0 (3) 0 0 (3) (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 (3) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Notes: (1) Use only the data values shown in Table 2 for spotlight function. (2) Either 1 or 0. (3) Always write a 0 to this bit. (4) Write a 0 to reset the FLTO bit for spotlight mode. 17 SC628A Serial Interface The I2C General Specification 2 The SC628A is a read-write slave-mode I C device and complies with the Philips I2C standard Version 2.1, dated January 2000. The SC628A 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 SC628A 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. SC628A Limitations to the I2C Specifications The SC628A 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. Supported Formats 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 by an eighth bit indicating a write. The SC628A 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 SC628A 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 SC628A 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 SC628A with a read command. The device acknowledges this request and returns the data from the register location that had previously been set up. 18 SC628A Serial Interface (continued) I2C Direct Format Write S Slave Address W A Register Address S – Start Condition W – Write = ‘0’ A – Acknowledge (sent by slave) P – Stop condition A Data A P Slave Address – 7-bit Register address – 8-bit Data – 8-bit I2C Stop Separated Format Read Master Addresses other Slaves 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 Slave Address B Register Read Access S/Sr Slave Address R A Data NACK P Data NACK P Slave Address – 7-bit Register address – 8-bit Data – 8-bit I2C Combined Format Read S Slave Address W A Register Address 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 A Sr Slave Address R A Slave Address – 7-bit Register address – 8-bit Data – 8-bit 19 SC628A Outline Drawing — MLPQ-UT-20 3x3 A D PIN 1 INDICATOR (LASER MARK) DIMENSIONS INCHES MILLIMETERS DIM MIN NOM MAX MIN NOM MAX B E A2 A SEATING PLANE aaa C A A1 A2 b D D1 E E1 e L N aaa bbb .020 .000 - .024 .002 (.006) .006 .008 .010 .114 .118 .122 .061 .067 .071 .114 .118 .122 .061 .067 .071 .016 BSC .012 .016 .020 20 .003 .004 0.50 0.00 - 0.60 0.05 (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 C A1 D1 e LxN E/2 E1 2 1 N D/2 bxN bbb C A B NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS . 3. DAP is 1.90 x 190mm. 20 SC628A Land Pattern — MLPQ-UT-20 3x3 H R (C) DIMENSIONS K G Y X P Z DIM INCHES MILLIMETERS C G H K P R X Y Z (.114) (2.90) .083 .067 .067 .016 .004 .008 .031 .146 2.10 1.70 1.70 0.40 0.10 0.20 0.80 3.70 NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. 3. 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. 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 21