LED backlights for tablet LCDs
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The LP8556 device is a white-LED driver featuring an asynchronous boost converter and six high precision current sinks that can be controlled by a PWM signal or an I2C master.
The boost converter uses adaptive output voltage control for setting the optimal LED driver voltages as low as 7 V and as high as 43 V. This feature minimizes the power consumption by adjusting the output voltage to the lowest sufficient level under all conditions. The converter can operate at three switching frequencies: 312 kHz, 625 kHz, and 1250 kHz, which can be set with an external resistor or pre-configured via EPROM. Programmable slew rate control and spread spectrum scheme minimize switching noise and improve EMI performance.
LED current sinks can be set with the PWM dimming resolution of up to 15 bits. Proprietary adaptive dimming mode allows higher system power saving. In addition, phase shifted LED PWM dimming allows reduced audible noise and smaller boost output capacitors.
The LP8556 device has a full set of fault-protection features that ensure robust operation of the device and external components. The set consists of input undervoltage lockout (UVLO), thermal shutdown (TSD), overcurrent protection (OCP), up to 6 levels of overvoltage protection (OVP), LED open and short detection.
The LP8556 device operates over the ambient temperature range of –30°C to +85°C. It is available in space-saving 20-pin DSBGA and 24-pad WQFN packages.
PART NUMBER | PACKAGE | BODY SIZE |
---|---|---|
LP8556 | DSBGA (20) | 2.401 mm × 1.74 mm (MAX) |
WQFN (24) | 4.00 mm × 4.00 mm (NOM) |
Changes from L Revision (May 2019) to M Revision
Changes from K Revision (March 2019) to L Revision
Changes from J Revision (January 2018) to K Revision
Changes from I Revision (March 2016) to J Revision
Changes from H Revision (December 2014) to I Revision
Changes from G Revision (November 2013) to H Revision
Changes from E Revision (August 2013) to G Revision
ORDERABLE DEVICE(1) | PACKAGE TYPE | DEVICE OPTION | LED CHANNEL COUNT | MAXIMUM LED CURRENT | BOOST OUTPUT VOLTAGE RANGE |
---|---|---|---|---|---|
LP8556SQ-E00/NOPB
LP8556SQE-E00/NOPB LP8556SQX-E00/NOPB |
WQFN | “PWM Only” – Recommended for systems without an I2C master. | 5 | 23 mA | 16 V to 34.5 V |
LP8556SQ-E08/NOPB
LP8556SQE-E08/NOPB LP8556SQX-E08/NOPB |
4 | ||||
LP8556SQ-E09/NOPB
LP8556SQE-E09/NOPB LP8556SQX-E09/NOPB |
6 | ||||
LP8556TME-E02/NOPB
LP8556TMX-E02/NOPB |
DSBGA | “PWM and I2C” - Recommended for systems with an I2C master. | 6 | 25 mA | 16 V to 30 V |
LP8556TME-E03/NOPB
LP8556TMX-E03/NOPB |
“PWM Only” – Recommended for systems without an I2C master. | 5 | 20 mA | 16 V to 34.5 V | |
LP8556TME-E04/NOPB
LP8556TMX-E04/NOPB |
6 | 20 mA | 16 V to 25 V | ||
LP8556TME-E05/NOPB
LP8556TMX-E05/NOPB |
“Non-programmed” – This option is for evaluation purposes only. | Can be programmed to any available. | 25 mA | Can be programmed to any available. | |
LP8556TME-E06/NOPB
LP8556TMX-E06/NOPB |
“PWM Only” – Recommended for systems without an I2C master. | 5 | 25 mA | 16 V to 39 V | |
LP8556TME-E07/NOPB
LP8556TMX-E07/NOPB |
4 | 20 mA | 12.88 V to 30 V | ||
LP8556TME-E09/NOPB
LP8556TMX-E09/NOPB |
6 | 23 mA | 16 V to 34.5 V | ||
LP8556TME-E11/NOPB
LP8556TMX-E11/NOPB |
“PWM and I2C” - Recommended for systems with an I2C master. | 3 | 23 mA | 7 V to 21 V |