Simple White LED Driver Circuit using TPS61161A

Light Emitting Diodes, or white LEDs, are quite common in current lighting applications.

They are especially useful in consumer electronics, vehicle displays, and general illumination because of their efficiency, durability, and adaptability.

To guarantee peak performance and long lifespan, however, power management for these LEDs must be dependable and effective.

A high-performance LED driver made especially for this use is the TPS61161A.

Several white LEDs can be driven in series by the TPS61161A step-up (boost) converter, which produces a steady current output necessary for reliable brightness and color quality.

With built-in characteristics including adjustable output current, broad input voltage range, and excellent efficiency, the TPS61161A improves dependability and makes designing LED driver circuits easier.

The main characteristics and advantages of utilizing the TPS61161A in white LED applications will be discussed in this article, along with its working principles, efficiency factors, and common uses.

Through comprehension of this LED drivers capabilities, designers may develop efficient solutions to fulfill the increasing need for superior LED illumination.

Circuit Working:

Parts List:

With only a few external parts, the white LED driver circuit utilizing the TPS61161A is intended to drive up to eight white LEDs.

To lessen output ripple, this integrated circuit runs at a set switching frequency of 600 kHz.

Its operating voltage range is 2.7V to 18V, and it has an integrated 38V open LED safety.

An external sensing resistor R1 is used to set the default LED current, and a 200 mV feedback voltage regulator is used.

An external PWM signal can be used to drive the control pin in order to reduce brightness.

The control pin is linked to the Vin supply via a resistor R2 in order to maintain the LEDs maximum brightness.

Via resistor R2, the Vin pin and the control pin get the Vin supply.

By means of the Schottky barrier diode D1 and the inductor L1, the white LEDs are supplied with Vin.

L1 and D1 are linked to the switching pin .

The cathode end of the series LEDs is connected to the feedback pin, while R1 is grounded on the other end for current monitoring.

The transconductance error amplifier outputs the COMP pin, and a capacitor is linked to compensate the regulator.

Formulas:

Using the TPS61161A, the following formulas and important equations can help in the analysis and design of the Simple White LED Driver Circuit:

LED Current Calculation:

The Ohms Law may be used to estimate the current flowing through the LED strings:

I_LED ​= V_LED​−V_D​​ / R_LED​

where,

• The forward voltage of the LED is represented by VLED.
• The diodes forward voltage drop is represented by VD, which is normally around 0.3V for a Schottky diode.
• The entire resistance in series with the LEDs, including R1 and any extra resistances, is represented as RLED.

Inductor Current:

The output voltage and duty cycle D may be used to compute the average inductor current:

I_L​ = V_OUT​ x D​ / L x f

where,

• The output voltage across the LEDs is represented by VOUT.
• L 22μH is the inductance.
• The switching frequency is represented by f

Output Voltage:

This kind of boost converter can have a relationship between the input voltage and duty cycle and the output voltage:

V_OUT​= V_IN​​ / 1−D

where,

• The input voltage, 5V is represented as VIN.
• D stands for duty cycle.

Capacitor Ripple Voltage:

One may use the following to determine the ripple voltage across the output capacitor C3:

V_ripple​ = ​I_LED​​ / f x C₃

where,

• The output current flowing through the LED strings is ILED.
• 1μF is the capacitance of C3.
• The frequency of switching is f.

Capacitor Charge/Discharge Time:

For a capacitor charging to a voltage Vf​:

t = R x C x ln (V_supply​−V_f / V_{supply​​​})

where,

• R is the resistance in series.
• C is the capacitance.
• Vsupply​ is the supply voltage 5V.
• Vf​ is the final voltage across the capacitor.

Power Output:

The total power delivered to the LEDs can be calculated using:

P_OUT​ = V_OUT​ x I_LED​

These formulas allow you to evaluate the LED driver circuits performance and make necessary component adjustments to get the required LED efficiency and brightness.

For proper design, be sure to verify the precise values listed in the TPS61161A datasheet.

How to Build:

To build a Simple White LED Driver Circuit using TPS61161A follow the connections steps below:

• Gather all the components as mentioned in the above circuit diagram.
• Connect PIN 1 of IC TPS61161A to GND through resistor R1 10Ω.
• Connect the cathode strings of all white LEDs to pin 1.
• Connect pin 2 of IC TPS61161A to one leg of capacitor C2 220nF and other leg to GND.
• Connect pin 3 of IC TPS61161A to GND.
• Connect pin 4 of IC TPS61161A between L1 22uH and diode D1MBR0540T1
• Connect pin 5 of IC TPS61161A to 5V positive supply through resistor R2 560Ω
• Connect pin 6 of IC TPS61161A to 5V positive supply.
• Connect a capacitor C1 1uF from 5V positive supply to GND.
• Connect the inductor L1 between the 5V supply and pin 4 of IC TPS61161A
• Connect the anode of Schottky Diode MBR0540T1 D1 with pin 4 and connect the cathode of diode to the positive end of the LEDs white strings.
• Connect the positive of the capacitor C3 1uF to the cathode of Schottky Diode D1 and connect the negative of capacitor with the GND supply.
• Connect the positive of 8 white LED strings to the junction of capacitor C3 1uF positive and the cathode of D1.

Conclusion:

To conclude, up to eight white LEDs can be powered by the effective and portable TPS61161A white LED driver circuit.

It reduces output ripple and offers a voltage range of 2.7V to 18V, with open LED protection up to 38V.

It operates at a set switching frequency of 600 kHz.

PWM functionality provides brightness dimming, and precise control of LED current is made possible by the addition of an external sensing resistor.

All things considered, the compact WSON packaging and its few components make it perfect for situations where space is at a premium, offering a dependable answer to contemporary LED lighting requirements.

References:

TPS6116x White LED Drivers With Digital and PWM Brightness Control in 2-mm x 2-mm
WSON Package