NPC SM8135AB

SM8135A
White LED Driver IC
OVERVIEW
The SM8135A is a charge pump type white LED driver. It can drive 1 to 4 backlight white LED connected in
parallel, making it ideal for portable devices with small LCD. The charge pump switches between ×1 bypass
mode, ×1.5 and ×2 boost mode in response to LED drive current requirements. The boost switching occurs in
response to the drive current of all the connected LED and thus supports variations in LED forward-bias voltage drop (VF). Besides, the detection of switching is repeated in approx. 1sec-cycle by mode reset action, the
SM8135A can respond to temporary variation of supply voltage. These ingenuities on switching detection can
prolong the battery life to the fullest extent. Each LED drive current is controlled by a 4-channel LED drive
current control circuit. The LED drive current per channel is setup by external resistor. Moreover, the PWM
signal control of EN pin can realize nonstep brightness control (10% to 100%). The IC ON/OFF is controlled
by EN pin.
■
■
■
■
■
GND
NC
DIN3
DIN4
PACKAGE DIMENSIONS
(Unit: mm)
TOP VIEW
3.0 ± 0.08
1.8
B
A
C 0.3
0.02 S A B
S
APPLICATIONS
■
■
■
■
■
■
■
■
Cellular phone
PDA
Portable games
Handy terminal
Digital still camera
Digital video camera
LCD panel back light
White LED driving
BOTTOM VIEW
1.8
■
3 = 1.5 ± 0.05
■
0.3 ± 0.1
■
■
0.5
■
ISET
EN
GND
VIN
C2M
PGND
C1P
C1M
■
■
DIN2
DIN1
VOUT
C2P
3.0 ± 0.08
■
(Top view)
0.22 ± 0.05
φ 0.05 M S A B
0.2 S
0.05 S
0.5
0.7 ± 0.05
■
Battery life extension by automatic charge pump
switch between ×1, ×1.5 and ×2 according to the
detection of the LED drive current
Controlling 1 to 4 lights of white LED connected
in parallel
Set up LED drive current value by external resistor
(120kΩ: 20mA/ch)
1-wire input controlling
ON/OFF and brightness control by PWM signal
controlling of EN pin (10 to 100%)
Soft start circuit built-in
Thermal shut down circuit built-in
Input voltage range
No-load current (IOUT = 0mA): 2.7 to 4.6V
Load current (IOUT = 80mA): 3.0 to 4.6V
Maximum output voltage: 4.9V (typ)
Maximum output current: 80mA (typ)
Quiescent current
Not-switching (×1 mode): 0.3mA (typ)
Switching (×1.5 mode): 1.5mA (typ)
Switching (×2 mode): 1.5mA (typ)
Standby current: 0.01µA (typ)
Operating frequency: 1MHz (typ)
LED drive current accuracy between channel
(REST = 120kΩ): ± 5% (max)
Package: 16-pin QFN
0.2 ± 0.05
■
PINOUT
0.1 ± 0.05
FEATURES
ORDERING INFORMATION
Device
Package
SM8135AB
16-pin QFN
SEIKO NPC CORPORATION —1
SM8135A
BLOCK DIAGRAM
C1M C1P C2M C2P
Charge pump
1/ 1.5/ 2
VIN
VOUT
DIN1
Mode control
&
Output voltage control
&
Protection
DIN2
Current
control
&
Current
detect
TSD
DIN3
DIN4
Control
logic
EN
ISET
NC
(open at any time)
GND
GND
PGND
PIN DESCRIPTION
Number
Name
I/O
Description
1
C2M
–
Charge pump boost capacitor connection 2M
2
PGND
–
Charge pump ground
3
C1P
–
Charge pump boost capacitor connection 1P
4
C1M
–
Charge pump boost capacitor connection 1M
5
VIN
–
Supply voltage input
6
GND
–
Ground
7
EN
I
Enable/PWM dimming pulse input (High active)
8
ISET
I
LED drive current setting resistor connection
9
DIN4
O
LED drive current control output 4 (connect to ground when not used)
10
DIN3
O
LED drive current control output 3 (connect to ground when not used)
11
NC
–
No connection (leave open circuit for normal operation)
12
GND
–
Ground
13
DIN2
O
LED drive current control output 2 (connect to ground when not used)
14
DIN1
O
LED drive current control output 1 (connect to ground when not used)
15
VOUT
O
LED drive voltage output
16
C2P
–
Charge pump boost capacitor connection 2P
SEIKO NPC CORPORATION —2
SM8135A
SPECIFICATIONS
Absolute Maximum Ratings
GND = 0V
Parameter
Symbol
Rating
Unit
VIN voltage range
VIN
−0.3 to 5.5
V
Input voltage range
VEN
–0.3 to VIN + 0.3
V
VDIN1 to 4
–0.3 to VIN + 0.3
V
VOUT
5.5
V
IOUT
500
mA
PD
800 (Ta = 25°C)*1
mW
TJMAX
+125
°C
Tstg
−55 to +125
°C
Output voltage range
VOUT output current
Power dissipation
Junction temperature
Storage ambient temperature range
*1. When mounted on a 4-layer PCB.
Note. The device may suffer breakdown if any one of these parameter ratings is exceeded.
Power dissipation [mW]
1000
800
600
400
200
0
25
35
45
55
65
Operating temperature [°C]
75
85
Package power dissipation when mounted on 4-layer board
Recommended Operating Conditions
GND = 0V
Rating
Parameter
Supply voltage range
Pin
VIN
Symbol
Conditions
Unit
min
typ
max
VIN0
IOUT = 0mA
2.7
3.6
4.6
V
VIN
IOUT = 80mA
3.3
3.6
4.6
V
Logic-level pin
0
−
VIN
V
−30
−
+85
°C
Input voltage range
EN
VES
Ambient temperature range
−
Ta
SEIKO NPC CORPORATION —3
SM8135A
Electrical Characteristics
VIN = 3.6V, GND = 0V, Ta = 25°C unless otherwise noted.
Rating
Parameter
Standby current
Quiescent current
Pin
VIN
VIN
Symbol
Condition
Unit
min
typ
max
ISTB
Standby mode
–
0.01
1.00
µA
IDD1
×1.0 mode, IOUT = 0mA
–
0.3
1.0
mA
×1.5 mode, IOUT = 0mA
–
1.5
4.5
mA
×2.0 mode, IOUT = 0mA
–
1.5
4.5
mA
4.4
4.9
5.4
V
IDD2
*1
IDD3
Output voltage
VOUT
VOUT
Maximum output current
VOUT
IOUT
×1.5/×2.0 mode
80
–
–
mA
Operating frequency
C1M
fOSC
×1.5/×2.0 mode switching frequency
750
1000
1250
kHz
EN
TPOR
Rest time from when power is applied
–
0.05
1.00
ms
Soft start time
DIN1 to 4
TSS
EN startup → ILED rising edge
0.70
1.43
3.00
ms
LED drive pin leakage current
DIN1 to 4
ILeak1 to 4
Standby mode, DIN pin = 4.9V
–
0.01
1.00
µA
LED drive current
DIN1 to 4
ILED1 to 4
×1.0 mode
18.0
20.0
22.0
mA
LED drive current matching
DIN1 to 4
∆ILED
×1.0 mode,
relative accuracy between channels
at ILED maximum setting
–5.0
–
+5.0
%
LED drive pin voltage
DIN1 to 4
VDIN1 to 4
×1.0 mode
–
200
–
mV
ISET
RSET
RSET minimum value
60
–
–
kΩ
EN hold time*1
EN
TCEH
Time from when EN = LOW until
shutdown
0.50
1.00
1.50
ms
PWM input pulse frequency*1
EN
fPWM
PWM dimming signal frequency
10
–
100
kHz
PWM input pulse duty*1
EN
DPWM
PWM dimming signal duty range
10
–
100
%
1.4
–
–
V
EN
VIH
HIGH-level input voltage range
Logic input voltage
VIL
LOW-level input voltage range
–
–
0.3
V
IIH
Pull-down pin, EN pin = 3.6V
–
5.0
10.0
µA
IIL
EN pin = 0V
–1.0
–
–
µA
Internal power-ON reset time*1
LED drive current
setting resistance*1
Logic input current
EN
*1. Design guaranteed value
SEIKO NPC CORPORATION —4
SM8135A
FUNCTIONAL DESCRIPTION
LED Drive Current Setting
The SM8135A LED drive current can be set using a combination of 2 methods: (1) current setting resistance
connected to ISET, and (2) PWM signal input control on the EN pin.
(1) Setting LED drive current using RSET
The LED drive maximum current value per LED (ILED MAX) is determined by the resistor (RSET) connected
to the ISET pin. The relationship between RSET and ILED MAX is given by the following equation.
ILED MAX [mA] = 2400/RSET [kΩ]
(For example, ILED MAX = 20mA when RSET = 120kΩ.)
The RSET resistance has a minimum rating of 60kΩ. At this value of resistance, the ILED MAX has a maximum
rating of 40mA/LED. However, note that the total LED drive current for all LEDs must not exceed 80mA.
50
RSET
ILED MAX [mA]
ISET
40
30
20
10
0
GND
0
100
200
300
400
500
RSET [kΩ]
RSET vs. ILED MAX
SEIKO NPC CORPORATION —5
SM8135A
(2) Setting LED current using PWM signal input on EN
The EN input is used to enable/disable circuit operation, but it can also be switched at speed using a PWM signal input to set the average LED drive current value. When using PWM signal input on EN only for dimming
control, the average LED drive current is given by the multiplication of the maximum current value (ILED MAX)
set by RSET and the PWM signal ON duty percentage.
ILED = ILED MAX × ON Duty [%]
The PWM signal ON duty is defined in the following figures (“PWM duty”). The PWM signal operating frequency range is 10kHz to 100kHz (10µs to 100µs per period), and the allowable duty range is 10 to 100%.
However, LED drive current that can be set by PWM signal has lower limit (= 2mA). When setting current to
2mA or less, even if the signal ON duty is within the allowable range, the current between pins varies widely.
High
EN
Low
DUTY100%
DUTY50%
DUTY10%
DUTY25%
turn on
(ILED MAX)
ILED MAX
ILED = ILED MAX
50%
ILED
ILED = ILED MAX
10%
ILED = ILED MAX
turn off
(0)
25%
turn off
(0)
0
Dimming control with PWM signal
1period
ON
interval
10µsec
OFF
interval
1period
100µsec
Duty [%] = ON interval/1period
ON
OFF
ILED = ILED MAX
Duty [%]
PWM duty
SEIKO NPC CORPORATION —6
SM8135A
VOUT Output Circuit Mode Switching
The SM8135A output mode switches between 4 operating modes in response to the operating conditions. The
modes are: standby mode, ×1.0 mode (VIN through mode), ×1.5 mode (1.5-times charge pump boost), and
×2.0 mode (2.0-times charge pump boost). Specifically, the use of ×1.0 mode, ×1.5 mode, and ×2.0 mode
allows the VOUT output to be adjusted automatically to match drive LED characteristics. Switching between
×1.0 mode, ×1.5 mode, and ×2.0 mode is controlled automatically by an internal circuit. The operating mode
cannot be specified by an external control signal.
Startup: Internal Reset Time and Soft Start Time
The SM8135A normal startup procedure (after VIN has been applied previously) is to switch from standby
mode to the ×1.0/×1.5/×2.0 operating modes when the EN enable input goes HIGH. The soft start time
(described on the following page) begins after switching to the operating mode using EN.
VIN
VIN High
(1)
Soft start time
EN
Standby mode
ENABLE ON
(2)
Normal startup
(1) VIN is HIGH, EN is LOW (standby mode)
(2) Switches to an operating mode when EN goes HIGH (soft start time begins)
If the VIN supply voltage is applied when EN is HIGH level, startup commences after the power-ON reset
(POR) time (approximately 50µs) has elapsed.
(1)
VIN power source
Internal
power on
reset
POR time
typ: 50µs
(2)
Soft start time
Internal
enable
(CE)
(3)
Standby mode
1.5 mode
Internal reset operation when power is applied (power-ON reset)
(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 EN 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 EN is LOW when power is applied, the “CE” rising edge
occurs simultaneously with the first rising edge.
SEIKO NPC CORPORATION —7
SM8135A
Immediately after startup, the device operates in ×1.5 mode for a fixed interval (soft start time: approximately
1.43ms) to set the current for LEDs connected to the DIN pins. After the soft start time has elapsed, the LEDs
are turned ON. Approximately 2ms is required for the LED drive current to reach the set drive value.
(1)
EN input signal
LED current
Soft start time
typ: 1.43ms
typ: 2ms
(2)
LED ON
Soft start time and LED current
(1) If the EN signal is input after power is applied, the soft start time begins on the EN rising edge. The PWM
signal input for dimming is active during the soft start time.
(2) After the soft start time (1.43ms) has elapsed, the LEDs are turned ON. Approximately 2ms is required for
LED drive current to reach set values.
Switching to Standby Mode
The SM8135A switches from ×1.0/×1.5/×2.0 mode to standby mode if EN goes LOW and stays LOW for an
interval of 1.00ms (typ). This function is used to switch the internal circuits to standby mode automatically
when the LEDs turn OFF in order to reduce current consumption.
EN
CE hold time
typ: 1.00ms
LED current
1.0 or 1.5
Standby
mode
EN input signal and internal enable signal “CE”
■
If EN is LOW for longer than the enable hold time of 1.00ms (typ), the SM8135A switches to standby mode.
In standby mode, the internal circuits are reset.
SEIKO NPC CORPORATION —8
SM8135A
Boost Mode Auto-switching
The SM8135A switches between ×1.0 mode (VIN through mode), ×1.5 mode (1.5-times charge pump boost),
and ×2.0 mode (2.0-times charge pump boost) automatically in response to the operating state to reduce current
consumption. The switching transition flow chart is shown in the following figure.
LED ON
1.0 mode
1.5 mode
ILED judgment
ILED judgment
insufficient
sufficient
insufficient
sufficient
1.5 mode
2.0 mode
1.0sec
1.0sec
Mode reset
1.5
1.0
Mode reset
2.0
1.5
ILED judgment
sufficient
ILED judgment
sufficient
insufficient
insufficient
Boost mode switching flow chart
This section describes the boost mode switching in response to insufficient LED drive current level detection.
The next section describes the mode reset functions. Initially, when the LED drive current begins to flow, operation begins in ×1.0 mode at the set current value if possible, without boosting the input voltage VIN. If the set
current value cannot be attained in ×1.0 mode due to a VIN voltage drop or an increase in the set current value,
a low-current detector circuit connected to each LED drive circuit is activated that switches the VOUT output
to ×1.5 mode automatically, and the charge pump circuit starts boosting the voltage by 1.5 times. If the set current value still cannot be attained, the LED drive circuits are switched to ×2.0 mode, and the charge pump starts
boosting the voltage by 2 times.
SEIKO NPC CORPORATION —9
SM8135A
1.0
1.5 threshold
1.5
VIN input voltage
2.0 threshold
Lack of LED
current detect
2.0 mode
VOUT mode
1.5 mode
1.0 mode
4.9V
VOUT output voltage
VIN voltage drop and VOUT output voltage
In ×1.0 mode, VIN = VOUT. However, the VOUT output does not always reach the electrical characteristics typical rating of 4.9V. However, as long as an insufficient current condition is not detected, ×1.0 mode operation
continues. In other words, VOUT may drop below 4.9V if sufficient LED drive current is flowing to counter the
LED forward-bias voltage drop VF. The longer the device can operate in the high output efficiency ×1.0 mode,
the lower the total current consumption and the longer the battery drive time can be extended. Furthermore, the
more that low VF LEDs and lower LED drive current are used, the longer the device can operate automatically
in ×1.0 mode.
1.0 mode
(high efficiency)
1.5 mode
2.0 mode
(low efficiency)
High VF LED
1.0 mode
(high efficiency)
1.5 mode
2.0 mode
(low efficiency)
Low VF LED
High
VIN input
Low
VOUT mode switching time comparison due to drive LED “VF” variation
The LED low-current detector circuit switches the output boost mode whenever a single insufficient current
condition is detected among the 4 channel LED drive currents, hence drive LEDs with small VF variation
should be used to increase overall efficiency. If, after startup, a LED connection to the DIN pins is switched
ON/OFF, the LED current detection circuit will operate incorrectly and normal boost mode switching does not
occur. Also, if LED drive current control using a DIM pin is not used, the low-current detector circuit does not
operate and the boost mode does not switch to either ×1.5 or ×2.0 mode.
SEIKO NPC CORPORATION —10
SM8135A
Mode Reset Function
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 SM8135A outputs a mode reset signal once every 1.0 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.
Mode reset
VOUT mode
Mode hold
L: hold
(1)
1.0sec/cycle
1.0 mode
1.5 mode
1.5 mode
(2)
min 80µs
max 200µs
(3)
ILED detector
ignore
4.9V
VOUT output voltage
(4)
ILED detector
Switching from ×1.5 mode to ×1.0 mode due to mode reset signal
(1) Mode reset signal is output once every 1.0 seconds.
(2) Mode switches from ×1.5 to ×1.0 mode on the rising edge of the mode reset signal.
(3) A 200µs (max) mode hold time begins after switching to ×1.0 mode. LED drive current insufficient state is
detected but the mode is not switched during this interval.
(4) LED drive current insufficient signal is ignored during the mode hold time, but normal mode switching
operation resumes when the mode hold time elapses.
SEIKO NPC CORPORATION —11
SM8135A
A mode hold signal of 200µs (max) duration is output immediately after switching to ×1.0 mode. The VOUT
output is held in ×1.0 mode and any LED drive current insufficient detection signal is ignored during the mode
hold signal output. For example, if the VIN voltage drops and the VOUT output voltage in ×1.0 mode cannot
provide sufficient current to drive the LEDs, a LED drive current insufficient condition occurs momentarily due
to the mode reset. The LED low-current detector circuit outputs a LED drive current insufficient signal immediately after switching modes, but during the mode hold time the device stays in ×1.0 mode and does not
switch to ×1.5 mode. Consequently, the VOUT voltage drops and the LED brightness decreases during the 85µs
(min) to 200µs (max) mode hold time. However, a 200µs decrease in the brightness is not a problem as it is not
perceptible to the human eye.
1.0
1.5 threshold
VIN input voltage
1.0sec
Mode reset
VOUT mode
max
200µS
Mode hold
(L: hold)
4.9V
VOUT output voltage
ILED detector
(H: lack)
VOUT drop due to mode reset signal (between ×1.5 and ×1.0 mode)
SEIKO NPC CORPORATION —12
SM8135A
The mode reset operation when in ×2.0 mode performs boost mode switching between ×2.0 mode and ×1.5
mode. Mode switching directly from ×2.0 mode to ×1.0 mode does not occur.
Mode reset
1.0sec/cycle
VOUT mode
2.0 mode
Mode hold
(L: hold)
1.5 mode
2.0 mode
min 80µs
max 200µs
ILED detector
ignore
4.9V
VOUT output voltage
ILED detector
Switching from ×2.0 mode to ×1.5 mode due to mode reset signal
(1) Mode switches from ×2.0 to ×1.5 mode on the rising edge of the mode reset signal.
(2) A 200µs (max) mode hold time begins after switching to ×1.5 mode. LED drive current insufficient state is
detected but the mode is not switched during this interval.
(3) LED drive current insufficient signal is ignored during the mode hold time, but normal mode switching
operation resumes when the mode hold time elapses.
The mode reset function periodically tests the boost mode to try to maximize the duration of operation in the
higher efficiency ×1.0 and ×1.5 modes in order to extend battery drive time.
Thermal Shutdown Circuit (Overtemperature Protection Circuit)
The SM8135A features a thermal shutdown circuit that operates whenever the IC temperature exceeds approximately 170°C for whatever reason, stopping the VOUT output. VOUT output recommences when the IC temperature falls below approximately 150°C.
SEIKO NPC CORPORATION —13
SM8135A
PERIPHERAL PARTS
About the External Capacitors
The best capacitors for use with the SM8135A 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.
SEIKO NPC CORPORATION —14
SM8135A
TYPICAL APPLICATION CIRCUITS
LED × 4, ILED = 20mA, without Dimming
C1 = 1µF
C1M C1P
2.7 to 4.6V
VIN
C2 = 1µF
C2M C2P
VOUT
Charge pump
1/ 1.5/ 2
C4 = 1µF
C3 = 1µF
20mA 4
DIN1
Mode control
&
Output voltage control
&
Protection
DIN2
Current
control
&
Current
detect
TSD
DIN3
DIN4
EN
Control
logic
ISET
RSET = 120kΩ
NC
(open at any time)
GND
GND
PGND
Note. If the driving LED is less than 4 pcs, unused DIN pins should be connect to GND.
ON/OFF control is performed using Enable signal input on EN with a fixed LED current determined by resistor RSET.
SEIKO NPC CORPORATION —15
SM8135A
LED × 4, ILED MAX = 20mA, PWM Pulse Input Dimming on EN
C1 = 1µF
C1M C1P
2.7 to 4.6V
VIN
C2 = 1µF
C2M C2P
VOUT
Charge pump
1/ 1.5/ 2
C4 = 1µF
C3 = 1µF
MAX 20mA 4
DIN1
Mode control
&
Output voltage control
&
Protection
DIN2
Current
control
&
Current
detect
TSD
DIN3
DIN4
EN
10kHz to 100kHz
Control
logic
ISET
RSET = 120kΩ
NC
(open at any time)
GND
GND
PGND
Note. If the driving LED is less than 4 pcs, unused DIN pins should be connect to GND.
Dimming and ON/OFF control is performed using PWM pulse input on EN with a maximum LED current determined by resistor
RSET (see P.6 “Setting LED current using PWM signal input on EN”).
The PWM control signal duty ratio must be in the range 10 to 100% (see “Electrical Characteristics”).
The PWM control signal frequency must be in the range 10kHz to 100kHz (see “Electrical Characteristics”).
SEIKO NPC CORPORATION —16
SM8135A
LED × 3, ILED MAX = 20mA, PWM Pulse Input Dimming on EN
C1 = 1µF
C1M C1P
2.7 to 4.6V
VIN
C2 = 1µF
C2M C2P
VOUT
Charge pump
1/ 1.5/ 2
C4 = 1µF
C3 = 1µF
MAX 20mA 3
DIN1
Mode control
&
Output voltage control
&
Protection
DIN2
Current
control
&
Current
detect
TSD
DIN3
DIN4 (connect to ground)
EN
10kHz to 100kHz
Control
logic
ISET
RSET = 120kΩ
NC
(open at any time)
GND
GND
PGND
Note. If the driving LED is less than 4 pcs, unused DIN pins should be connect to GND.
Dimming and ON/OFF control is performed using PWM pulse input on EN with a maximum LED current determined by resistor
RSET (see P.6 “Setting LED current using PWM signal input on EN”).
The PWM control signal duty ratio must be in the range 10 to 100% (see “Electrical Characteristics”).
The PWM control signal frequency must be in the range 10kHz to 100kHz (see “Electrical Characteristics”).
SEIKO NPC CORPORATION —17
SM8135A
LED × 2, ILED MAX = 29.3mA, PWM Pulse Input Dimming on EN
C1 = 1µF
C1M C1P
2.7 to 4.6V
VIN
C2 = 1µF
C2M C2P
VOUT
Charge pump
1/ 1.5/ 2
C4 = 1µF
C3 = 1µF
MAX 29.3mA 2
DIN1
Mode control
&
Output voltage control
&
Protection
DIN2
Current
control
&
Current
detect
TSD
DIN3 (connect to ground)
DIN4 (connect to ground)
EN
10kHz to 100kHz
Control
logic
ISET
RSET = 82kΩ
NC
(open at any time)
GND
GND
PGND
Note. If the driving LED is less than 4 pcs, unused DIN pins should be connect to GND.
Dimming and ON/OFF control is performed using PWM pulse input on EN with a maximum LED current determined by resistor
RSET (see P.6 “Setting LED current using PWM signal input on EN”).
The PWM control signal duty ratio must be in the range 10 to 100% (see “Electrical Characteristics”).
The PWM control signal frequency must be in the range 10kHz to 100kHz (see “Electrical Characteristics”).
SEIKO NPC CORPORATION —18
SM8135A
FOOTPRINT PATTERN
3.6 ± 0.1
2.2 ± 0.1
0.
32
0.25 ± 0.05
0.7 ± 0.1
2.2 ± 0.1
0.5 × 3 = 1.5 ± 0.05
3.6 ± 0.1
0.5 × 3 = 1.5 ± 0.05
SEIKO NPC CORPORATION —19
SM8135A
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 SEIKO NPC CORPORATION (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.
SEIKO NPC CORPORATION
15-6, Nihombashi-kabutocho, Chuo-ku,
Tokyo 103-0026, Japan
Telephone: +81-3-6667-6601
Facsimile: +81-3-6667-6611
http://www.npc.co.jp/
Email: [email protected]
NC0602AE
2007.01
SEIKO NPC CORPORATION —20