SM8131B White LED Driver IC OVERVIEW The SM8131B is a charge pump DC/DC converter that switches between ×1 and ×1.5 automatically. The SM8131B switches between ×1 and ×1.5 according to detected LED drive current, so that the battery life can be prolonged to the fullest extent. Since the connected LED are all detected for the switching, the SM8131B can respond to the variation of LED forward voltage. 6-channel of LED drive current control circuit is built-in, the SM8131B can control 1 to 6 lights of white LED, which are connected in parallel. The LED drive current per channel is set up by external resistor. Besides, by setting up SEL1/SEL2 pins, 6-channel of LED drive current control circuit can be divided to 2-groups, and input signal controlling of EN1/EN2 pins allow ON/OFF and dimming per group. ■ ■ ■ ■ ■ ■ ■ ■ ■ EN2 SEL1 SEL2 VOUT VIN PACKAGE DIMENSIONS (Unit: mm) 4.20 ± 0.20 4.00 ± 0.10 1 0.50 0.60 ± 0.10 0.05 APPLICATIONS ■ ■ ■ ■ ■ ■ ■ ■ Cellular phone PDA Portable games Handy terminal Digital still camera Digital video camera LCD back light White LED driving 0.22 ± 0.05 0.05 M 0.22 ■ 1 2 3 4 5 1.00MAX ■ VREG C2P C2M PGND C1M 10 9 8 7 6 16 17 18 19 20 + 0.03 0.02 − 0.02 ■ 15 14 13 12 11 EN1 DIN6 DIN5 DIN4 GND DIN3 DIN2 DIN1 ISET C1P ■ (Top view) 4.00 ± 0.10 ■ Battery life extension by automatic charge pump switch between ×1 and ×1.5 according to the detection of the LED drive current Controlling 1 to 6 lights of white LED connected in parallel Set up LED drive current value by external resistor (5kΩ:5mA/ch, 15kΩ:15mA/ch, 20kΩ:20mA/ch) Dividing 6-channel to 2-groups by setting up SEL1/SEL2 pins (L/L = 6:0ch, L/H = 5:1ch, H/L = 4:2ch, H/H = 3:3ch) 2-wire input controlling (1-wire input controlling when SEL1/SEL2 pins are set to “LOW”) ON/OFF and brightness control by input signal controlling of EN1/EN2 pins Supply voltage range • No-load current (IOUT = 0mA): 2.7 to 4.6V • Load current (IOUT = 120mA): 3.3 to 4.6V Maximum output voltage: 4.2V (typ) Maximum output current: 120mA (typ) Quiescent current • Not-switching (×1 mode): 0.7mA (typ) • Switching (×1.5 mode): 2.0mA (typ) Standby current (Power save mode): 0.01µA (typ) Operating frequency (×1.5 mode): 750kHz (typ) LED drive current accuracy (RSET = 20kΩ) :20mA ± 3% Input signal frequency for dimming (Duty = 50%) :150kHz (max) Package:20-pin QFN 20 ■ PINOUT 4.20 ± 0.20 FEATURES ORDERING INFORMATION Device Package SM8131B00B 20-pin QFN NIPPON PRECISION CIRCUITS INC.—1 SM8131B BLOCK DIAGRAM GND DIN4 DIN5 DIN6 EN1 EN2 Control logic DIN3 LED current control DIN2 SEL1 SEL2 DIN1 ISET VOUT mode controller C1P 1.5 Charge pump C1M PGND C2M VOUT VIN VREG C2P VREG PIN DESCRIPTION Number Name I/O 1 DIN3 O LED drive current control output 3 (connect to GND when not used) 2 DIN2 O LED drive current control output 2 (connect to GND when not used) 3 DIN1 O LED drive current control output 1 (connect to GND when not used) 4 ISET I LED drive current setting resistor connection 5 C1P – Charge pump capacitor connection 1P 6 C1M – Charge pump capacitor connection 1M 7 PGND – Charge pump ground connection 8 C2M – Charge pump capacitor connection 2M 9 C2P – Charge pump capacitor connection 2P 10 VREG – LED drive current control voltage monitor (Don't connect any lines) 11 VIN – Voltage supply 12 VOUT O LED driving voltage output 13 SEL2 I Group setting data input 2 14 SEL1 I Group setting data input 1 EN2 Ip*1 Group B enable data input (High active) 16 EN1 Ip*1 Group A enable data input (High active) 17 DIN6 O LED drive current control output 6 (connect to GND when not used) 18 DIN5 O LED drive current control output 5 (connect to GND when not used) 19 DIN4 O LED drive current control output 4 (connect to GND when not used) 20 GND – Ground 15 Description *1. Input with built-in pull-down resistor NIPPON PRECISION CIRCUITS INC.—2 SM8131B SPECIFICATIONS Absolute Maximum Ratings Parameter Symbol Rating Unit VIN voltage range VIN −0.3 to 6.5 V Input voltage range VEN, VSEL VGND – 0.3 to VIN + 0.3 V VDIN1 to 6 VGND – 0.3 to VIN + 0.3 V VOUT 6.5 V Power dissipation PD 1429 (Ta = 25°C)*1 mW Operating temperature range Ta –30 to 85 °C Storage temperature range Tstg −55 to 125 °C Output voltage range *1.When mounted on a 34 × 40 × 1.6mm glass epoxy board, the power dissipation is related to the operating temperature by the following equation. ■ ■ Maximum junction temperature: TMAX = 125°C Operating temperature: Ta [°C] Thermal resistance: θJ = 70°C/W PD = (TMAX − Ta) θJ 1600 1429 Power dissipation [mW] ■ 1143 1200 857 800 571 400 0 25 35 45 55 65 75 85 Operating temperature [°C] NIPPON PRECISION CIRCUITS INC.—3 SM8131B Electrical Characteristics VIN = 3.6V, GND = 0V, Ta = 25°C unless otherwise noted Rating Parameter Supply voltage range Pin VIN Standby current VIN Quiescent current VIN Symbol Condition Unit min typ max VIN0 ×1.0 mode, IOUT = 0mA 2.7 3.6 4.6 V VIN ×1.5 mode, IOUT = 120mA 3.3 3.6 4.6 V ISTB Power-save mode – 0.01 1.00 µA IDD1 ×1.0 mode, IOUT = 0mA – 0.7 1.5 mA IDD2 ×1.5 mode, IOUT = 0mA – 2.0 4.0 mA 4.0 4.2 4.4 V – 120 – mA Output voltage VOUT VOUT ×1.5 mode, IOUT = 120mA Maximum output current VOUT IOUT ×1.5 mode Operating frequency C1M fOSC ×1.5 mode switching frequency 650 750 850 kHz EN TPOR Time from when power is applied until internal circuits reset – 0.05 1.0 ms Soft start time DIN1 to 6 TSS EN startup → ILED rising edge – 1.3 5.0 ms LED drive pin leakage current DIN1 to 6 Ileak1 to 6 Power-save mode, DIN pin = 4.2V – 0.01 1.00 µA LED drive current DIN1 to 6 ILED1 to 6 ×1.0 mode, RSET = 20kΩ 19.4 20.0 20.6 mA LED drive current setting resistance*1 ISET RSET RSET maximum value – – 50 kΩ Input signal frequency*1 EN1/2 fENIN EN input pulse duty 50%, maximum signal input frequency – – 150 kHz Input pulse width*1 TENH Minimum EN pulse HIGH-level width 3.0 – – EN1/2 µs TENL Minimum EN pulse LOW-level width 3.0 – – µs Time from when EN1 = EN2 = LOW until LED drive circuit shutdown 1.17 1.37 1.63 ms Internal power-ON reset time*1 Hold time EN1/2 TCEH EN1/2, SEL1/2 VIH HIGH-level input voltage range 1.8 – – V Input voltage VIL LOW-level input voltage range – – 0.6 V EN1/2 IIH Pull-down pin, EN pin = 3.6V – 5.0 10.0 µA Input current *1. Design guaranteed value NIPPON PRECISION CIRCUITS INC.—4 SM8131B VOUT Efficiency 100 VOUT efficiency [%] 90 80 70 VF = 3.2V VF = 3.4V VF = 3.6V 60 VF = 3.8V 50 3.2 3.4 3.6 3.8 4.0 VIN [V] 4.2 4.4 4.6 4.4 4.6 Efficiency of PIN vs. POUT (LED × 6pcs, ILED = 20mA, IOUT = 120mA) 100 VOUT efficiency [%] 90 80 VF = 3.2V 70 VF = 3.4V VF = 3.6V VF = 3.8V 60 50 3.2 3.4 3.6 3.8 4.0 VIN [V] 4.2 Efficiency of PIN vs. POUT (LED × 3pcs, ILED = 15mA, IOUT = 45mA) NIPPON PRECISION CIRCUITS INC.—5 SM8131B FUNCTIONAL DESCRIPTION LED Drive Current Setting The SM8131B LED drive current setting is controlled by the combination of resistance connected to ISET and the EN input signals. (1) Setting LED Drive Current using RSET The maximum drive current per LED (when DATA = 1) is determined by the external resistance connected to ISET. For example, if ILED MAX = 15mA, from the graph below, a resistance “RSET” of 15kΩ should be connected between ISET and GND. Note that while RSET can have a maximum resistance 50kΩ, the total LED output current must not exceed the maximum output current of 120mA. 50 40 ILED MAX [mA] ISET RSET 30 20 10 GND 0 0 10 20 30 40 50 RSET [kΩ] LED drive current maximum setting using RSET (2) Setting LED Drive Current using EN Input Signals The EN input ENABLE/DISABLE circuit, also simultaneously counts the number of input pulses using an internal counter and adjusts the LED drive current setting in response. The internal 4-bit counter provides 16step (DATA = 1 to 16) adjustment, where each step is 1/15th of the maximum current (ILED MAX) set by RSET. On the 16th pulse (DATA = 16), the LED drive current control circuit shuts down. On the 17th pulse (DATA = 1), the LED drive current is reset to the maximum current value. As the current is set to the maximum value on the first pulse, applications without pulse input can also be employed (by controlling brightness using RSET). RSET=10kΩ RSET=15kΩ RSET=20kΩ EN1 25 123 ILED [mA] 20 EN input pulse 15 10 5 0 GND 0 4 8 12 16 DATA set by EN input pulse LED drive current setting variation using EN input pulse modulation Table. LED drive current setting and EN input pulse count DATA EN pulse count ILED 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 15/15 14/15 13/15 12/15 11/15 10/15 9/15 8/15 7/15 6/15 5/15 4/15 3/15 2/15 1/15 0 NIPPON PRECISION CIRCUITS INC.—6 SM8131B EN input signal and LED drive current setting (startup) An internal startup signal goes HIGH on the first rising edge of either EN1 or EN2, and LED drive current starts after the soft-start time expires. The LED drive current control circuit sets the current by counting the input pulses on EN, hence the EN input voltage must be switched HIGH → LOW → HIGH the required number of data steps to reduce the current setting. When the desired setting is reached, the EN input voltage should be tied HIGH to maintain the setting. Note that the LED drive current does not flow when EN is LOW between pulses, momentarily switching the group of LEDs OFF. The EN data input circuit operates during the soft-start time when no LED drive current flows, hence the current setting can be adjusted during the soft-start time and the LED drive circuit will then start at the desired current setting. However, setting the current using EN signal pulses is possible only when the power-ON reset ends after a rising edge on the VIN supply. Consequently, a delay of 1ms or greater should be allowed after VIN is applied before starting the EN input signals. EN1 input signal ILED group A setting EN2 input signal ILED group B setting 1 1 2 2 3 4 3 5 6 4 1 1 5 2 2 3 3 6 4 4 7 7 8 8 5 5 EN input signal and LED drive current setting ■ The LED drive current in group A (group B) is set by the number of EN1 (EN2) input signal rising-edge. When either EN1 or EN2 input signal first rises, the internal enable signal CE goes HIGH, and the IC is enabled. The LED drive current control circuit is disabled, and the LED drive current does not flow during EN input signal LOW interval or at startup until after the soft-start time expires. NIPPON PRECISION CIRCUITS INC.—7 SM8131B EN input signal and LED drive current setting (disable interval) The LED drive current setting due to EN input is set by the 4-bit counter (16 steps). On the 17th pulse, the counter DATA = 1 and the current is reset to the maximum current value. When the counter DATA = 16, ILED = 0mA and the LED drive circuit shuts down. 11 12 13 14 15 16 17 18 19 20 21 EN1 input ILED disable signal ILED off 1 LED current 11 12 13 14 2 3 4 5 15 16 LED drive current setting disable interval When both EN1 and EN2 are held LOW for an extended interval, the internal enable signal “CE” goes LOW and the device enters power-save mode. In this mode, the EN input internal counter is reset and subsequent rising-edge pulses on EN restart the counter from DATA = 1. SEL inputs and LED control groups The DIN1 to DIN6 6-channel LED drive pins can be divided into two groups of drive pins (EN1 control and EN2 control drive pins) by the state of select inputs SEL1 and SEL2. Two groups with separate LED drive current control using EN1 and EN2 allows a single device to independently adjust the backlight brightness of 2 screens. With a MODE 6:0 setting, EN2 is not used and should be connected to GND. Also, any unused DIN LED drive pins should be connected to GND. Table. SEL setting and LED drive pin grouping SEL input LED control signal MODE SEL1 SEL2 DIN1 DIN2 DIN3 DIN4 DIN5 DIN6 6:0 setting L L EN1 EN1 EN1 EN1 EN1 EN1 5:1 setting L H EN1 EN1 EN1 EN1 EN1 EN2 4:2 setting H L EN1 EN1 EN1 EN1 EN2 EN2 3:3 setting H H EN1 EN1 EN1 EN2 EN2 EN2 NIPPON PRECISION CIRCUITS INC.—8 SM8131B VOUT Output Circuit Mode Switching The SM8131B switches between 3 output states: power-save mode (standby state), ×1.0 mode (VIN through mode), and ×1.5 mode (×1.5 charge pump boost). This automatically adjusts the VOUT output to match the drive LED characteristics and reduces the total power dissipation. Switching to and from ×1.0 and ×1.5 mode occurs automatically in an internal circuit, and cannot be controlled using an external input. Power-ON internal reset time The SM8131B switches from standby condition (power-save mode) to normal operating condition (×1.0/×1.5 mode) on the first rising edge of either EN1 or EN2. Note that if the VIN supply voltage is applied when EN1 or EN2 is HIGH, startup occurs after the internal power-ON reset time (approximately 50µs) expires. At startup, operation commences in ×1.5 mode for a fixed interval during the soft-start time in order to determine whether a LED is connected to each DIN pin. VIN power source (1) VIN Power on reset output POR time typ: 50µs (2) Soft start time Internal enable (CE) (3) Power save mode 1.5 mode Power-ON reset operation (1) VIN voltage rises when power is applied. (2) Power-ON reset (POR) circuit resets internal circuits approximately 50µs after the power is applied. (3) If EN1 or EN2 is HIGH when power is applied, the internal circuits start operating when the internal “CE” signal rising edge occurs after the power-ON reset time. If EN1 and EN2 are LOW when power is applied, the “CE” rising edge occurs simultaneously with the first rising edge. EN1 input signal LED current EN1 (1) Dimming pulses enable Soft start time typ: 1.3ms LED ON (2) Soft start time and LED current (1) If the EN signals are input after POR time is expired, the soft start time begin from the first EN input rising edge. The current setting can be adjusted during the soft-start time. (2) LED current starts flow immediately before the soft start time expires. NIPPON PRECISION CIRCUITS INC.—9 SM8131B Switching to power-save mode The internal circuit operating mode switches from ×1.0/×1.5 mode to power-save mode when both EN1 and EN2 go LOW and do not switch HIGH for an interval of 1.63ms (max). This function turns the LEDs OFF and automatically transfers internal circuit control to power-save mode, suppressing current consumption. EN1 input EN2 input EN1+EN2 Internal enable (CE) (1) Power save 1.0 or 1.5 CE hold time 1.63ms (max) Power save (2) EN input signal and internal enable signal “CE” (1) If the EN signals are input after power is applied and the POR time has expired, the internal enable signal “CE” switches with the EN1 + EN2 signal. (2) If the internal enable signal “CE” goes from HIGH to LOW and are held for an interval greater than the “CE” hold time 1.63ms (max), the SM8131B switches to power-save mode. The internal circuits are reset on the “CE” falling edge, and the current setting must be re-established before restart. NIPPON PRECISION CIRCUITS INC.—10 SM8131B Switching from ×1.0 mode to ×1.5 mode If the LEDs can be driven solely by the current determined by RSET and EN pulse input without boosting the VIN input voltage, the VOUT output operates in ×1.0 mode. In other words, if sufficient current flows even with the LED forward-direction voltage drop “VF”, then VOUT is less than 4.2V. Operation in the more efficient ×1.0 mode reduces the total power dissipation and extends the battery drive time. And if low “VF” LEDs are used or the LED drive current setting is LOW, the operating time in ×1.0 mode is also extended. 1.0 mode (high efficiency) 1.5 mode (low efficiency) 1.0 mode (high efficiency) 1.5 mode (low efficiency) High VF LED Low VF LED High Low VIN input VOUT mode switching time comparison due to drive LED “VF” variation If the VIN voltage falls or RSET increases such that the LED drive current is too low in ×1.0 mode, then the LED drive circuit low-current detector operates, the VOUT output is automatically switched to ×1.5 mode, and the charge pump boosts the output voltage. This occurs even if only one LED low-current condition is detected among the 6-channel LED drive circuits, thus it is recommended that LEDs have small “VF” variation to optimize the total efficiency. VIN input voltage 1.0 Low ILED detector 1.5 threshold (1) Low ILED detected VOUT mode (2) 1.0 mode 1.5 mode 4.2V VOUT output voltage (3) VIN voltage drop and VOUT output voltage (1) When VIN falls, VOUT cannot overcome the LED “VF” rating, causing insufficient current flows and the ILED low-current signal becomes active. (2) When the ILED low-current condition is detected, the VOUT output circuit switches to ×1.5 mode (charge pump mode). (3) Prior to switching to ×1.5 mode, the VOUT voltage may be lower than 4.2V but sufficient current is supplied to the LED. If after startup, the LED connected to a DIN pin is switched, the LED connection detector circuit flags an error, and correct mode switching may not occur. If the DIN pin does not control the LED drive current, the low-current detector does not operate and the device cannot switch to ×1.5 mode. NIPPON PRECISION CIRCUITS INC.—11 SM8131B Switching from ×1.5 mode to ×1.0 mode VF increases immediately after the LED current starts to flow, and then decreases as the LED temperature increases due to the heating effect of the current flow. It can take about 10 seconds for the LED temperature to stabilize and for VF to reach equilibrium, and VF may fluctuate more than 200mV. The VF fluctuation is affected by the ambient temperature and LED current setting, and has a large affect on the automatic mode switching voltage tolerances. To counter the effects of VF fluctuation, the SM8131B outputs a mode reset signal once every 1.4 seconds which automatically switches the output mode to ×1.0, and then a determination is made whether to make the ×1.0 → ×1.5 mode switch. 1.4sec/cycle (1) Mode reset (2) VOUT mode 1.5 mode 1.0 mode min 85µs max 200µs Mode hold L: hold (3) ILED detector ignore VOUT output voltage 4.2V (4) Low ILED detector (5) Switching from ×1.5 to ×1.0 mode due to the mode reset signal (1) Mode reset signal is output once every 1.4 seconds. (2) Switching from ×1.5 to ×1.0 mode due to the mode reset signal pulse. (3) The mode hold time of 200µs (max) starts when output switches to ×1.0 mode. During this interval, the mode is not switched even if an ILED undercurrent condition is detected. (4) If VIN is low, the VOUT voltage momentarily drops because the boost function stops as a result of switching to ×1.0 mode. (5) The ILED undercurrent signal is ignored during the mode hold time, and the mode only switches in response to the detector output after the mode hold time expires. NIPPON PRECISION CIRCUITS INC.—12 SM8131B For example, if the VIN voltage is low and the VOUT output voltage in ×1.0 mode does not provide sufficient drive current, then the mode reset will cause a LED undercurrent condition. The LED undercurrent detector circuit will output an LED undercurrent signal immediately after the switch to ×1.0 mode, but the output will stay in ×1.0 mode and not return to ×1.5 mode for the duration of the mode hold time. Consequently, the VOUT output is not boosted during the 85µs (min) to 200µs (max) mode hold time and the voltage drops and the LED brightness is reduced. However, the LEDs are OFF for a maximum of 200µs only, and this is not discernible to the naked eye and thus is not a problem. 1.0 1.5 threshold VIN input voltage Mode reset (1.4sec/cycle) Mode hold (H: hold) 1.4sec max 200µS VOUT mode (H: 1.5, L: 1.0) 4.2V VOUT output voltage Low ILED detector (H: low ILED) VOUT drop due to the mode reset single NIPPON PRECISION CIRCUITS INC.—13 SM8131B VIN Input Voltage Range The VIN minimum input voltage value to ensure rated drive current flows in each LED is determined by the ILED setting (largest setting if divided into 2 groups), the total load current IOUT on pin VOUT, and the LED forward-direction voltage drop “VF”, as given in the following equations: (1) VF ≤ 1.5 × VIN − 10 × IOUT − 8 × ILED (2) VIN ≥ (VF + 10 × IOUT + 8 × ILED)/1.5 where 1.5 is the charge pump boost factor, 10 is the VOUT output impedance, and 8 is the LED drive circuit internal resistance. For example, if VIN = 3.5V, ILED = 20mA, and IOUT = 120mA, then VF is given by equation as follows: 1.5 × 3.5 − 10 × 0.12 − 8 × 0.02 = 3.89 [V] Thus if LEDs with VF of 3.89V or lower rating at ILED = 20mA are used, the device will provide sufficient drive current. If VIN falls and the drive LED VF exceeds the calculated value, VIN will take ILED down with it below the required setting. The relationship in equation is shown graphically for values of IOUT = 30/60/90/120mA. 5.5 IOUT = 30mA IOUT = 60mA LED VF [V] 5.0 IOUT = 90mA IOUT = 120mA 4.5 4.0 3.5 3.0 2.5 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 VIN [V] VIN voltage and LED forward-direction voltage drop limit value NIPPON PRECISION CIRCUITS INC.—14 SM8131B PERIPHERAL PARTS About the External Capacitors The best capacitors for use with the SM8131B are multi-layer ceramic capacitors. When selecting a multi-layer ceramic capacitor, only X5R and X7R dielectric types are strongly recommended, since the loss of capacitance in various conditions is less than other types such as Z5U and Y5V. The much loss of capacitance in various conditions may cause the output voltage unstable. Table. The EIA three digit "TC" code Lower temperature limit High temperature limit Maximum allowable capacitance change from + 25°C (0V DC) X = − 55°C 5 = + 85°C F = ± 7.5% Y = − 30°C 6 = + 105°C P = ± 10% Z = + 10°C 7 = + 125°C R = ± 15% 8 = + 150°C S = ± 22% T = + 22%/− 33% U = + 22%/− 56% V = + 22%/− 82% For example : X5R About the Input Capacitor "C4" The parts layout of PCB may merely cause the “VOUT” output voltage unstable. In this case, increasing the “C4” input capacitance value or adding another capacitor on the VIN input line is effective to solve the unstable output voltage. About the LED Current Setting Resistor "RSET" The LED drive current variation depends on the LED drive current setting resistor “RSET” variation. Therefore, a precise resistor is recommended for RSET. The ISET output current value is about 20µA, so a 1/10 watt class resistor is acceptable as the RSET. NIPPON PRECISION CIRCUITS INC.—15 SM8131B TYPICAL APPLICATION CIRCUITS MODE 6:0 setting SEL1 = SEL2 = LOW EN1 = LED control input for group A (ON/OFF and dimmer) EN2 = LOW Group A = 6pcs (DIN1, DIN2, DIN3, DIN4, DIN5, DIN6) Group B = 0pcs RSET = 20kΩ (ILED MAX = 20mA) C1 = C2 = 1µF (X5R or X7R) GND DIN3 Group A DIN2 Group A DIN1 Group A DIN5 DIN6 EN1 EN2 EN2 = L LED current control SEL1 SEL1 = L SEL2 SEL2 = L VOUT mode controller RSET 20kΩ (ILED MAX = 20mA) DIN4 LED control input for group A (ON/OFF and dimmer) Control logic Group A Group A Group A C3 = C4 = 4.7µF (X5R or X7R) ISET VOUT 1.5 Charge pump VREG C1P VIN VIN C3 C1M PGND C2M C2P C1 1µF C2 1µF (X5R or X7R) (X5R or X7R) 4.7µF VREG Open (X5R or X7R) GND C4 4.7µF (X5R or X7R) GND MODE 6:0 setting, ILED MAX = 20mA circuit example NIPPON PRECISION CIRCUITS INC.—16 SM8131B MODE 5:1 setting SEL1 = LOW SEL2 = HIGH EN1 = LED control input for group A (ON/OFF and dimmer) EN2 = LED control input for group B (ON/OFF and dimmer) Group A = 5pcs (DIN1, DIN2, DIN3, DIN4, DIN5) Group B = 1pcs (DIN6) RSET = 20kΩ (ILED MAX = 20mA) C1 = C2 = 1µF (X5R or X7R) GND DIN4 LED control input for group A (ON/OFF and dimmer) Group B Group A Group A C3 = C4 = 4.7µF (X5R or X7R) DIN5 DIN6 EN1 LED control input for group B (ON/OFF and dimmer) DIN3 Group A DIN2 Group A DIN1 EN2 LED current control SEL1 SEL1 = L SEL2 SEL2 = H VOUT mode controller RSET 20kΩ (ILED MAX = 20mA) Control logic Group A ISET VOUT 1.5 Charge pump VREG C1P VIN VIN C3 C1M PGND C2M C2P C1 1µF C2 1µF (X5R or X7R) (X5R or X7R) 4.7µF VREG Open (X5R or X7R) GND C4 4.7µF (X5R or X7R) GND MODE 5:1 setting, ILED MAX = 20mA circuit example NIPPON PRECISION CIRCUITS INC.—17 SM8131B MODE 4:2 setting SEL1 = HIGH SEL2 = LOW EN1 = LED control input for group A (ON/OFF and dimmer) EN2 = LED control input for group B (ON/OFF and dimmer) Group A = 4pcs (DIN1, DIN2, DIN3, DIN4) Group B = 2pcs (DIN5, DIN6) RSET = 20kΩ (ILED MAX = 20mA) C1 = C2 = 1µF (X5R or X7R) GND DIN4 LED control input for group A (ON/OFF and dimmer) Group B Group B Group A C3 = C4 = 4.7µF (X5R or X7R) DIN5 DIN6 EN1 LED control input for group B (ON/OFF and dimmer) DIN3 Group A DIN2 Group A DIN1 EN2 LED current control SEL1 SEL1 = H SEL2 SEL2 = L VOUT mode controller RSET 20kΩ (ILED MAX = 20mA) Control logic Group A VOUT ISET 1.5 Charge pump VREG C1P VIN VIN C3 C1M PGND C2M C2P C1 1µF C2 1µF (X5R or X7R) (X5R or X7R) 4.7µF VREG Open (X5R or X7R) GND C4 4.7µF (X5R or X7R) GND MODE 4:2 setting, ILED MAX = 20mA circuit example NIPPON PRECISION CIRCUITS INC.—18 SM8131B MODE 3:3 setting SEL1 = SEL2 = HIGH EN1 = LED control input for group A (ON/OFF and dimmer) EN2 = LED control input for group B (ON/OFF and dimmer) Group A = 3pcs (DIN1, DIN2, DIN3) Group B = 3pcs (DIN4, DIN5, DIN6) RSET = 20kΩ (ILED MAX = 20mA) C1 = C2 = 1µF (X5R or X7R) GND DIN4 DIN5 LED control input for group A (ON/OFF and dimmer) Group B Group B Group B C3 = C4 = 4.7µF (X5R or X7R) DIN6 EN1 LED control input for group B (ON/OFF and dimmer) DIN3 Group A DIN2 Group A DIN1 EN2 LED current control SEL1 SEL1 = H SEL2 SEL2 = H VOUT mode controller RSET 20kΩ (ILED MAX = 20mA) Control logic Group A ISET VOUT 1.5 Charge pump VREG C1P VIN VIN C3 C1M PGND C2M C2P C1 1µF C2 1µF (X5R or X7R) (X5R or X7R) 4.7µF VREG Open (X5R or X7R) GND C4 4.7µF (X5R or X7R) GND MODE 3:3 setting, ILED MAX = 20mA circuit example NIPPON PRECISION CIRCUITS INC.—19 SM8131B ASSEMBLING PRECAUTION Package corner metals are not IC I/O pins. Don’t connect any lines to these corner metals. Bottom view FOOTPRINT PATTERN The optimum footprint varies depending on the board material, soldering paste, soldering method, and equipment accuracy, all of which need to be considered to meet design specifications. (Unit: mm) HE HD e b3 l1 l2 QFN-20 4.2 4.2 0.5 0.30 ± 0.05 0.20 ± 0.05 0.70 ± 0.05 HE /2 Package b3 HE e b3 l1 e l2 l2 l1 HD /2 HD NIPPON PRECISION CIRCUITS INC.—20 SM8131B Please pay your attention to the following points at time of using the products shown in this document. The products shown in this document (hereinafter “Products”) are not intended to be used for the apparatus that exerts harmful influence on human lives due to the defects, failure or malfunction of the Products. Customers are requested to obtain prior written agreement for such use from NIPPON PRECISION CIRCUITS INC. (hereinafter “NPC”). Customers shall be solely responsible for, and indemnify and hold NPC free and harmless from, any and all claims, damages, losses, expenses or lawsuits, due to such use without such agreement. NPC reserves the right to change the specifications of the Products in order to improve the characteristic or reliability thereof. NPC makes no claim or warranty that the contents described in this document dose not infringe any intellectual property right or other similar right owned by third parties. Therefore, NPC shall not be responsible for such problems, even if the use is in accordance with the descriptions provided in this document. Any descriptions including applications, circuits, and the parameters of the Products in this document are for reference to use the Products, and shall not be guaranteed free from defect, inapplicability to the design for the mass-production products without further testing or modification. Customers are requested not to export or re-export, directly or indirectly, the Products to any country or any entity not in compliance with or in violation of the national export administration laws, treaties, orders and regulations. Customers are requested appropriately take steps to obtain required permissions or approvals from appropriate government agencies. NIPPON PRECISION CIRCUITS INC. 4-3, Fukuzumi 2-chome, Koto-ku, Tokyo 135-8430, Japan Telephone: +81-3-3642-6661 Facsimile: +81-3-3642-6698 http://www.npc.co.jp/ Email: [email protected] NC0322BE 2004.04 NIPPON PRECISION CIRCUITS INC.—21