s-8813 Seiko Instruments Inc., s-8813 Datasheet - Page 17

• Manufacturer Part Number: s-8813
• Description: 3-channel White Led Driver Ic Charge Pump Ic With Built-in Constant-current Circuit
• Manufacturer: Seiko Instruments Inc.

PWM Control Signal Conditions:
Output Impedance of the PWM Output Control Signal Source (R
Calculation of I
Ideally, when the duty ratio is 0%, I
resistance of R
R
Therefore, the I
Caution 1. Fix the PWM output to low level during standby (when the
Rev.2.1
Z
means the output impedance of the PWM control signal source when the PWM control signal is low level.
2. When the PWM duty is set to 100%, the current to the LED will be switched off. However, the
3. The duty ratio indicates the percentage of the high-level pulse width to one period.
3-CHANNEL WHITE LED DRIVER IC (CHARGE PUMP IC WITH BUILT-IN CONSTANT-CURRENT CIRCUIT)
_00
PWM Output is set to high level, leak current will flow.
IC will still keep operation. This is not the same as standby mode, and so the current
consumption will be the same as in normal operation mode.
OUT
1
OUT
. However, the impedance from the RISET pin to the GND will serve as R
According to PWM Duty Ratio: I
value varies depend on the R
Figure 26 Wave Form Example of PWM Control signal
f
V
V
V
V
V
PWM
P-P
IH:
IL
IH
IL
OUT
:
f
V
PWM
V
: Pulse amplitude
V
: Pulse frequency
P-P
IH
IL
Pulse input voltage (“H”)
Pulse input voltage (“L”)
value is the 100 times value of the RISET pin voltage (1 V) divided by the
100 Hz
2.0 V
2.0 V
PWM Duty Ratio=
Min.
0 V
Z
Seiko Instruments Inc.
value.
OUT
=1 V / (R
T
OFF
T
Typ.
⎯
⎯
⎯
⎯
T
1
ON
+R
Z
): Max.500 Ω
T
Z
) × 100 × (1-Duty ratio)
OFF
T
20 kHz
4.5 V
4.5 V
Max.
0 V
ON/
OFF
pin is low level). If the
1
+R
Z
in actual operation.
S-8813 Series
17