Analog Integrated Circuit Device Data

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14

Freescale Semiconductor

34844

FUNCTIONAL DESCRIPTION

FUNCTIONAL PIN DESCRIPTION

EXTERNAL PWM INPUT (PWM)

This terminal is internally pulled down. An external PWM signal can be applied to modulate the LED channel directly in absence of an

I2C interface.

CLOCK I2C SIGNAL (SCK)

Clock line for I2C communication.

ADDRESS I2C SIGNAL (SDA)

Address line for I2C communication.

A0/SEN

Address select, device select pin, or hardware overvoltage protection (OVP) control.

CURRENT SET (ISET)

Each LED string can drive up to 50 mA. The maximum current can be set by using a resistor from this pin to GND.

POSITIVE CURRENT SCALING (PIN)

Positive current scaling factor for the external analog current control. Applying 0 V to this pin, scales the current to near 0%, and in the

same way, applying VSET (2.048 V Typ.), the scale factor is 100%. By applying a voltage higher than 2.2 V, the scaling factor is disabled,

and the internal pull-ups are activated.

If PIN pin and NIN pin are used at the same time then by applying 0 V to the PIN pin and VSET to NIN pin, scales the current to near

0%, and in the same way, applying VSET to the PIN pin and 0 V to NIN pin, scales the current to 100%. By applying a voltage higher than

2.2 V, the scaling factor is disabled and the internal pull-ups are activated in both pins.

NEGATIVE CURRENT SCALING (NIN)

Negative current scaling factor for the external analog current control. Setting 0 V to this pin scales the current to 100%, in the same

way, setting VSET (2.048 V Typ.) the scale factor is near 0%. By applying a voltage higher than 2.2 V, the scaling factor is disabled and

the internal pull-ups are activated.

If the PIN and NIN pin are used at the same time, then by applying 0 V to the PIN pin and VSET to NIN pin, it scales the current to near

0%, and in the same way, applying VSET to the PIN pin and 0 V to NIN pin, scales the current to 100%. By applying a voltage higher than

2.2 V, the scaling factor is disabled and the internal pull-ups are activated in both pins.

GROUND (GND)

Ground Reference for all internal circuits other than the Boost FET. The Exposed Pad (EP) should be used for thermal heat dissipation.

I0-I9

Current LED driver, each line has the capability of driving up to 50 mA.

FAULT DETECTION PIN (FAIL)

When a fault situation is detected, this pin goes into high-impedance.

BOOST SLOPE COMPENSATION SETTING RESISTOR (SLOPE)

The resistor to be used for the SLOPE depends on the Input and Output voltage difference as well as the inductor value. Use the formula

shown in the Components Calculation section to calculate the value accordingly.

POWER GROUND TERMINALS (PGNDA, PGNDB)

Ground terminal for the internal Boost FET.

OUTPUT VOLTAGE SENSE TERMINAL (VOUT)

Input terminal to monitor the output voltage. It supplies the input voltage for the internal regulator 2 (VDC2).

SWITCHING NODE TERMINALS (SWA, SWB)

Switching node of boost converter.