* : Main office: 2-4-3 Fukusumi, Koto-ku Tokyo, President: Yoshifumi Gomi
*1: EMI = Electromagnetic Interference
*2: ESD: Electrostatic Discharge
An overview and technological features of each product are described below.
SM8121AH
SM8130 series
(1) The SM8120AH and SM8121AH are highly efficient and reduce LED current variations
The SM8120AH and SM8121AH employ a switching regulator that has excellent power efficiency. By increasing the switching speed while reducing the current consumption at the same time, these driver ICs have realized an efficiency of driving a white LED of more than 85%. The maximum output voltage is 25 V (24 V with the SM8120AH). As a result, two to six white LEDs (two to four with the SM8120AH) that are connected in series can be lighted.
These two products have reduced the LED brightness variations by using two techniques. One is LED series connection. This has completely eliminated the relative current variations between LEDs. Another is improving the accuracy of the reference voltage. As a result, the LED current detection error has been successfully reduced to +/-2%. If an external resistor with an absolute accuracy of +/-0.5% for LED current setting, the current of all LEDs can be controlled at an absolute accuracy of +/-2.5%, which makes a great contribution to reducing the LED brightness variation during mass production of the application system.
The SM8120AH employs PFM (Pulse Frequency Modulation) for controlling a voltage increase. PFM controls the input current by changing the switching frequency when the input voltage or output load (LED current) changes. This can reduce the current consumption and maintains a high efficiency when the LED current is low.
The SM8121AH uses PWM (Pulse Width Modulation) for controlling a voltage increase. This changes the switching pulse width to control the input current when the input voltage or output load (LED current) changes. As a result, the peak value of the input current can be held constant and reduce the ripple voltage even if the input voltage changes.
(2) The SM8130 series with excellent EMI noise immunity and easy protection against ESD
The SM8130 series employs a charge pump with excellent EMI noise immunity. In addition, it is provided with three channels of LED current control circuits that reduce variations to +/-3%. Consequently, these driver ICs can drive white LEDs with the fewer components and take up less mounting area. Specifically, a 10-pin super small lead-less package SON (Small Outline Nonlead) is used to reduce the dimensions to 2.9 x 3.0 x 0.8 mm. With only three external capacitors, a white LED driver circuit can be created in a very limited mounting area.
The forward current variation of white LEDs connected in parallel is determined by the forward voltage variation of these LEDs. Usually, a resistor is connected in series to each LED in order to reduce this variation. Because the SM8130 series has three channels of LED current control circuits that reduce variation to +/-3%, it can control the current of one to three white LEDs connected in parallel, without having to connect a series resistor to each LED.
When one or two white LEDs are used, or when the LED current control circuit is not used, the unused LED current control pin is opened. The built-in LED current limiting circuit prevents an overcurrent (30 mA per channel) from flowing into the LED current control circuit. These functions protect the IC and LEDs from damage if the white LEDs are opened or short-circuited because of a trouble during mounting. The anode and cathode of a white LED are connected to the mating pins of the IC, so that the LED is protected from ESD by the operation of the built-in ESD protection circuit of the IC.
NPC plans to develop more products using the element technologies employed in these driver ICs. |
 Major features and functions |
| <SM8120AH/SM8121AH> |
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Step-up high-efficiency drive (maximum efficiency: 85%) |
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LED current can be set by external resistor. |
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Brightness can be adjusted by PWM control (100 to 400 Hz) of CE (Chip Enable) pin. |
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Regulation control method: PFM (SM8120AH), PWM (SM8121AH). |
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Number of LEDs: 2 to 4 (SM8120AH), 2 to 6 (SM8121AH) |
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Input voltage range: 2.4 to 5.5 V (SM8120AH), 2.3 to 5.5 V (SM8121AH) |
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Output voltage range: VDD to 24 V (SM8120AH), VDD to 25 V (SM8121AH) |
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Current consumption (typ.): 80 µA (SM8120AH), 400 µA (SM8121AH) |
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Standby current (max.): 10 µA |
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Output current detection accuracy: +/-2% |
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Maximum operating frequency: 500 kHz+/-10% (SM8120AH) |
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Operating frequency: 1.0 MHz+/-10% (SM8121AH) |
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Switching transistor output resistance (typ.): 2 ohms |
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Package: 5-pin SOT23 |
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| <SM8130 series> |
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Double charge pump type without coil |
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LED current can be set by CONT pin. |
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Brightness can be controlled by controlling voltage on CONT pin. |
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Regulation control method: Input series regulator plus output charge pump |
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Number of LEDs: 1 to 3 |
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Input voltage range: 2.7 to 4.6 V |
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Output voltage: 5.0 V +/-4% |
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Current consumption (typ.): 3.5 mA |
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Standby current (max.): 1.0 µA |
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LED current accuracy: 20 mA +/-3% (VCONT = 0.50 V) |
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Operating frequency: 500 kHz +/-10% |
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Output resistance: 10 ohms (typ.) |
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Package: 10-pin SON |
Other information |
| <SM8120AH> |
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Price of sample: 300 yen/unit |
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Mass production and delivery schedule: January 2003 |
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Production quantity: 500,000 units/month |
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| <SM8121AH> |
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Price of sample: 300 yen/unit |
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Mass production and delivery schedule: May 2003 |
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Production quantity: 1 million units/month |
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| <SM8130 series> |
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Price of sample: 400 yen/unit |
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Sample delivery schedule: May 2003 |
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Mass production and delivery schedule: June 2003 |
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Production quantity: 1 million units/month |
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For more information,
Sales Group
TEL +81-3-3642-6663 FAX +81-3-3642-6698 sales@npc.co.jp
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