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SM8131B White LED Driver IC
OVERVIEW
The SM8131B is a charge pump DC/DC converter that switches between x1 and x1.5 automatically. The SM8131B switches between x1 and x1.5 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.
FEATURES
I
PINOUT
(Top view)
EN2 SEL1 SEL2 VOUT VIN
15 14 13 12 11
I I I
I I I
I I I
I I I I I
0.05
0.05 M
I I I I I I I I
Cellular phone PDA Portable games Handy terminal Digital still camera Digital video camera LCD back light White LED driving
ORDERING INFORMATION
Device SM8131B00B Package 20-pin QFN
NIPPON PRECISION CIRCUITS INC.--1
+ 0.03 0.02 - 0.02
APPLICATIONS
0.22 0.05
1.00MAX
0.22
Battery life extension by automatic charge pump switch between x1 and x1.5 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 (5k:5mA/ch, 15k:15mA/ch, 20k: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 (x1 mode): 0.7mA (typ) * Switching (x1.5 mode): 2.0mA (typ) Standby current (Power save mode): 0.01A (typ) Operating frequency (x1.5 mode): 750kHz (typ) LED drive current accuracy (RSET = 20k) :20mA 3% Input signal frequency for dimming (Duty = 50%) :150kHz (max) Package:20-pin QFN
EN1 DIN6 DIN5 DIN4 GND
16 17 18 19 20 12345
10 9 8 7 6
VREG C2P C2M PGND C1M
PACKAGE DIMENSIONS
(Unit: mm)
4.20 0.20 4.00 0.10
4.20 0.20
4.00 0.10
20
1 0.50
DIN3 DIN2 DIN1 ISET C1P
0.60 0.10
SM8131B
BLOCK DIAGRAM
GND
DIN4
DIN5
DIN6
EN1
DIN3
EN2
DIN2
LED current control
Control logic
SEL1
DIN1
SEL2
ISET
VOUT mode controller
VOUT
C1P
1.5 Charge pump
VREG
VIN
C1M
PGND
C2M
C2P
VREG
PIN DESCRIPTION
Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Name DIN3 DIN2 DIN1 ISET C1P C1M PGND C2M C2P VREG VIN VOUT SEL2 SEL1 EN2 EN1 DIN6 DIN5 DIN4 GND I/O O O O I - - - - - - - O I I Ip*1 Ip*1 O O O - Description LED drive current control output 3 (connect to GND when not used) LED drive current control output 2 (connect to GND when not used) LED drive current control output 1 (connect to GND when not used) LED drive current setting resistor connection Charge pump capacitor connection 1P Charge pump capacitor connection 1M Charge pump ground connection Charge pump capacitor connection 2M Charge pump capacitor connection 2P LED drive current control voltage monitor (Don't connect any lines) Voltage supply LED driving voltage output Group setting data input 2 Group setting data input 1 Group B enable data input (High active) Group A enable data input (High active) LED drive current control output 6 (connect to GND when not used) LED drive current control output 5 (connect to GND when not used) LED drive current control output 4 (connect to GND when not used) Ground
*1. Input with built-in pull-down resistor NIPPON PRECISION CIRCUITS INC.--2
SM8131B
SPECIFICATIONS
Absolute Maximum Ratings
Parameter VIN voltage range Input voltage range Output voltage range Power dissipation Operating temperature range Storage temperature range Symbol VIN VEN, VSEL VDIN1 to 6 VOUT PD Ta Tstg Rating -0.3 to 6.5 VGND - 0.3 to VIN + 0.3 VGND - 0.3 to VIN + 0.3 6.5 1429 (Ta = 25C)*1 -30 to 85 -55 to 125 Unit V V V V mW C C
*1.When mounted on a 34 x 40 x 1.6mm glass epoxy board, the power dissipation is related to the operating temperature by the following equation.
I I I
Maximum junction temperature: TMAX = 125C Operating temperature: Ta [C] Thermal resistance: J = 70C/W
PD =
(TMAX - Ta) J
1600 1429 Power dissipation [mW] 1200 1143 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 = 25C unless otherwise noted
Rating Parameter Pin Symbol VIN0 VIN Standby current Quiescent current Output voltage Maximum output current Operating frequency Internal power-ON reset time*1 Soft start time LED drive pin leakage current LED drive current LED drive current setting resistance*1 Input signal frequency*1 Input pulse width*1 VIN VIN VOUT VOUT C1M EN DIN1 to 6 DIN1 to 6 DIN1 to 6 ISET EN1/2 ISTB IDD1 IDD2 VOUT IOUT fOSC TPOR TSS Ileak1 to 6 ILED1 to 6 RSET fENIN TENH TENL Hold time EN1/2 EN1/2, SEL1/2 EN1/2 TCEH VIH VIL IIH Condition min Supply voltage range VIN x1.0 mode, IOUT = 0mA x1.5 mode, IOUT = 120mA Power-save mode x1.0 mode, IOUT = 0mA x1.5 mode, IOUT = 0mA x1.5 mode, IOUT = 120mA x1.5 mode x1.5 mode switching frequency Time from when power is applied until internal circuits reset EN startup ILED rising edge Power-save mode, DIN pin = 4.2V x1.0 mode, RSET = 20k RSET maximum value EN input pulse duty 50%, maximum signal input frequency Minimum EN pulse HIGH-level width Minimum EN pulse LOW-level width Time from when EN1 = EN2 = LOW until LED drive circuit shutdown HIGH-level input voltage range LOW-level input voltage range Pull-down pin, EN pin = 3.6V 2.7 3.3 - - - 4.0 - 650 - - - 19.4 - - 3.0 3.0 1.17 1.8 - - typ 3.6 3.6 0.01 0.7 2.0 4.2 120 750 0.05 1.3 0.01 20.0 - - - - 1.37 - - 5.0 max 4.6 4.6 1.00 1.5 4.0 4.4 - 850 1.0 5.0 1.00 20.6 50 150 - - 1.63 - 0.6 10.0 V V A mA mA V mA kHz ms ms A mA k kHz s s ms V V A Unit
EN1/2
Input voltage Input current *1. Design guaranteed value
NIPPON PRECISION CIRCUITS INC.--4
SM8131B
VOUT Efficiency
100
90
VOUT efficiency [%]
80
70
VF = 3.2V 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 4.4 4.6
Efficiency of PIN vs. POUT (LED x 6pcs, ILED = 20mA, IOUT = 120mA)
100
90
VOUT efficiency [%]
80
70
VF = 3.2V 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 4.4 4.6
Efficiency of PIN vs. POUT (LED x 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 15k should be connected between ISET and GND. Note that while RSET can have a maximum resistance 50k, the total LED output current must not exceed the maximum output current of 120mA.
50
ILED MAX [mA]
ISET
40 30 20 10
RSET
GND
0 0 10 20 30 40 50 RSET [k]
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=10k RSET=15k RSET=20k
EN1
123
ILED [mA]
25 20 15 10 5
EN input pulse
GND
0 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 1 1 EN pulse count 17 33 49 ILED 2 2 18 34 50 3 3 19 35 51 4 4 20 36 5 5 21 37 6 6 22 38 7 7 23 39 8 8 24 40 9 9 25 41 10 10 26 42 11 11 27 43 12 12 28 44 13 13 29 45 14 14 30 46 15 15 31 47 16 16 32 48
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
1
2
3
4
5
6
7
8
ILED group A setting
1
2
3
4
5
6
7
8
EN2 input signal
1
2
3
4
5
ILED group B setting
1
2
3
4
5
EN input signal and LED drive current setting
I
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.
EN1 input
11 12 13 14 15 16 17 18 19 20 21
ILED disable signal
ILED off
LED current 11 12 13 14 15 16
1
2
3
4
5
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 MODE 6:0 setting 5:1 setting 4:2 setting 3:3 setting SEL1 L L H H SEL2 L H L H DIN1 EN1 EN1 EN1 EN1 DIN2 EN1 EN1 EN1 EN1 LED control signal DIN3 EN1 EN1 EN1 EN1 DIN4 EN1 EN1 EN1 EN2 DIN5 EN1 EN1 EN2 EN2 DIN6 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), x1.0 mode (VIN through mode), and x1.5 mode (x1.5 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 x1.0 and x1.5 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 (x1.0/x1.5 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 50s) expires. At startup, operation commences in x1.5 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 VIN
(1)
Power on reset output
POR time typ: 50s
(2)
Internal enable (CE)
Power save mode
Soft start time (3) 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 50s 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
EN1
Dimming pulses enable
(1)
LED current
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 x1.0/x1.5 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
(1)
Internal enable (CE)
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 x1.0 mode to x1.5 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 x1.0 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 x1.0 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 x1.0 mode is also extended.
1.0 mode (high efficiency)
High VF LED
1.5 mode (low efficiency)
1.0 mode (high efficiency)
Low VF LED High VIN input
1.5 mode (low efficiency)
Low
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 x1.0 mode, then the LED drive circuit low-current detector operates, the VOUT output is automatically switched to x1.5 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
1.5 threshold
Low ILED detector
Low ILED detected
(1)
VOUT mode
(2) 1.0 mode 1.5 mode
VOUT output voltage
4.2V
(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 x1.5 mode (charge pump mode). (3) Prior to switching to x1.5 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 x1.5 mode.
NIPPON PRECISION CIRCUITS INC.--11
SM8131B Switching from x1.5 mode to x1.0 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 x1.0, and then a determination is made whether to make the x1.0 x1.5 mode switch.
1.4sec/cycle Mode reset
(1)
VOUT mode
(2)
1.5 mode 1.0 mode
Mode hold L: hold
min 85s max 200s
ILED detector ignore
(3)
VOUT output voltage
4.2V (4)
Low ILED detector
(5)
Switching from x1.5 to x1.0 mode due to the mode reset signal (1) Mode reset signal is output once every 1.4 seconds. (2) Switching from x1.5 to x1.0 mode due to the mode reset signal pulse. (3) The mode hold time of 200s (max) starts when output switches to x1.0 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 x1.0 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 x1.0 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 x1.0 mode, but the output will stay in x1.0 mode and not return to x1.5 mode for the duration of the mode hold time. Consequently, the VOUT output is not boosted during the 85s (min) to 200s (max) mode hold time and the voltage drops and the LED brightness is reduced. However, the LEDs are OFF for a maximum of 200s only, and this is not discernible to the naked eye and thus is not a problem.
1.0
VIN input voltage
1.5 threshold
Mode reset (1.4sec/cycle) Mode hold (H: hold)
VOUT mode (H: 1.5, L: 1.0)
1.4sec
max 200S
VOUT output voltage Low ILED detector (H: low ILED)
4.2V
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 x VIN - 10 x IOUT - 8 x ILED (2) VIN (VF + 10 x IOUT + 8 x 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 x 3.5 - 10 x 0.12 - 8 x 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 5.0 LED VF [V] 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 IOUT = 30mA IOUT = 60mA IOUT = 90mA IOUT = 120mA
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 X = - 55C Y = - 30C Z = + 10C High temperature limit 5 = + 85C 6 = + 105C 7 = + 125C 8 = + 150C Maximum allowable capacitance change from + 25C (0V DC) F = 7.5% P = 10% R = 15% 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 20A, 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 = 20k (ILED MAX = 20mA) C1 = C2 = 1F (X5R or X7R) C3 = C4 = 4.7F (X5R or X7R)
Group A
Group A
GND
DIN4
DIN5
DIN6
Group A
LED control input for group A (ON/OFF and dimmer)
EN1
Group A
DIN3 LED current control Control logic
EN2 EN2 = L
Group A
DIN2
SEL1 SEL1 = L
Group A
DIN1 VOUT mode controller ISET
SEL2 SEL2 = L
RSET
20k (ILED MAX = 20mA)
VOUT
1.5 Charge pump C1P C1M
C1 1F
(X5R or X7R)
VREG
VIN
C3
4.7F
VIN
PGND
C2M
C2P
C2 1F
(X5R or X7R)
VREG Open
C4
4.7F
(X5R or X7R)
(X5R or X7R) GND
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 = 20k (ILED MAX = 20mA) C1 = C2 = 1F (X5R or X7R) C3 = C4 = 4.7F (X5R or X7R)
Group A
Group A
GND
DIN4
DIN5
DIN6
Group B
LED control input for group A (ON/OFF and dimmer)
EN1
LED control input for group B (ON/OFF and dimmer)
Group A
DIN3 LED current control Control logic
EN2
Group A
DIN2
SEL1 SEL1 = L
Group A
DIN1 VOUT mode controller ISET
SEL2 SEL2 = H
RSET
20k (ILED MAX = 20mA)
VOUT
1.5 Charge pump C1P C1M
C1 1F
(X5R or X7R)
VREG
VIN
C3
4.7F
VIN
PGND
C2M
C2P
C2 1F
(X5R or X7R)
VREG Open
C4
4.7F
(X5R or X7R)
(X5R or X7R) GND
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 = 20k (ILED MAX = 20mA) C1 = C2 = 1F (X5R or X7R) C3 = C4 = 4.7F (X5R or X7R)
Group A
Group B
GND
DIN4
DIN5
DIN6
Group B
LED control input for group A (ON/OFF and dimmer)
EN1
LED control input for group B (ON/OFF and dimmer)
Group A
DIN3 LED current control Control logic
EN2
Group A
DIN2
SEL1 SEL1 = H
Group A
DIN1 VOUT mode controller ISET
SEL2 SEL2 = L
RSET
20k (ILED MAX = 20mA)
VOUT
1.5 Charge pump C1P C1M
C1 1F
(X5R or X7R)
VREG
VIN
C3
VIN
PGND
C2M
C2P
C2 1F
(X5R or X7R)
VREG Open
C4
4.7F
(X5R or X7R) GND
4.7F
(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 = 20k (ILED MAX = 20mA) C1 = C2 = 1F (X5R or X7R) C3 = C4 = 4.7F (X5R or X7R)
Group B
Group B
GND
DIN4
DIN5
DIN6
Group B
LED control input for group A (ON/OFF and dimmer)
EN1
LED control input for group B (ON/OFF and dimmer)
Group A
DIN3 LED current control Control logic
EN2
Group A
DIN2
SEL1 SEL1 = H
Group A
DIN1 VOUT mode controller ISET
SEL2 SEL2 = H
RSET
20k (ILED MAX = 20mA)
VOUT
1.5 Charge pump C1P C1M
C1 1F
(X5R or X7R)
VREG
VIN
C3
VIN
PGND
C2M
C2P
C2 1F
(X5R or X7R)
VREG Open
C4
4.7F
(X5R or X7R) GND
4.7F
(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)
Package QFN-20 HE 4.2 HD 4.2 e 0.5 b3 0.30 0.05 l1 0.20 0.05 l2 0.70 0.05
b3
e HE b3 e l1 l2 l2 l1 HD /2 HD
NIPPON PRECISION CIRCUITS INC.--20
HE /2
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: sales@npc.co.jp
NC0322BE 2004.04
NIPPON PRECISION CIRCUITS INC.--21

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