LP8556 datasheet(5/52 Pages) TI

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LP8556

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SNVS871B – JULY 2012 – REVISED SEPTEMBER 2012

PIN DESCRIPTIONS

uSMD

WQFN

Name

Type(1)

Description

A1, B1

1, 2

A connection to the drain terminal of the integrated power MOSFET.

A2, B2

3, 4

GND_SW

A connection to the source terminal of the integrated power MOSFET.

SDA

I/O

I2C data input/output pin.

SCL

I2C clock input pin.

PWM dimming input. Supply a 75 Hz to 25 kHz PWM signal to control

PWM

dimming. This pin must be connected to GND if unused.

Dual purpose pin serving both as a Chip enable and as a power supply

EN / VDDIO

reference for PWM, SDA and SCL inputs. Drive this pin with a logic

gate capable of sourcing a minimum of 1 mA.

Device power supply pin. Provide 2.7V to 20V supply to this pin. This

VDD

pin is an input of the internal LDO regulator. The output of the internal

LDO is what powers the device.

Boost converter output pin. The internal Feedback (FB) and Over-

VBOOST

voltage Protection (OVP) circuitry monitors the voltage on this pin.

Connect the converter output capacitor bank close to this pin.

A connection for setting the boost frequency and PWM output dimming

frequency by using an external resistor. Connect a resistor, RFSET,

FSET

between this pin and the ground reference (See Table 5). This pin may

be left floating if PWM_FSET_EN=0 AND BOOST_FSET_EN=0 (See

Table 9).

LED3

LED driver - current sink terminal. If unused, it may be left floating.

Internal LDO output pin. Connect a capacitor, CVLDO, between this pin

VLDO

and the ground reference.

A connection for the LED current set resistor. Connect a resistor,

ISET

RISET, between this pin and the ground reference. This pin may be left

floating if ISET_EN=0 (See Table 9).

10, 11, 15, 24,

GND

Ground pin.

DAP

LED2

LED driver - current sink terminal. If unused, it may be left floating.

LED6

LED driver - current sink terminal. If unused, it may be left floating.

LED5

LED driver - current sink terminal. If unused, it may be left floating.

LED4

LED driver - current sink terminal. If unused, it may be left floating.

LED1

LED driver - current sink terminal. If unused, it may be left floating.

No Connect pin.

(1)

A: Analog Pin, G: Ground Pin, P: Power Pin, I: Digital Input Pin, I/O: Digital Input/Output Pin

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

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