LED Driver Circuit Using CAT3603

CAT3603 is a three channel charge pump LED driver IC from Catalyst Semiconductors that can be operated in either LDO mode or fractional mode. The IC can deliver 30mA per channel and can be operated from an input voltage range of 3 to 5.5V DC. CAT3063 has a quiescent current as low as 0.1uA and this makes it suitable for battery powered applications. The operating frequency is 1Mhz which makes it possible to use small capacitors.

LED Driver Circuit Diagram Using CAT3603

Another features are soft start, current limiting, high efficiency (90%) and short circuit protection. Applications of this IC are hand held devices, LCD back lights , LED lighting gadgets etc. The output current can be programmed using an external resistor connected between the RSET (pin 4) and ground.

Charge pump:

Charge pump is a DC to DC converter circuit that uses capacitors as the energy storage component for creating an output voltage that is either higher or lower than the input voltage. A switching circuit (using BJTs or MOSFETs) is used for connecting and disconnecting the voltages from the storage capacitor.

The switching frequency is usually in the kilo or MHz range. The output voltage will be a pulsed one and it is smoothed using an output filter capacitor. Charge pump circuits can double, triple, quadruple, multiply or scale any given voltage. In theory, a charge pump can generate any desired voltage.

CAT3063 LED driver circuit.

The circuit diagram of a three channel LED driver circuit using CAT3063 is shown below (Fig 1). C4 is an input filter capacitor. R1 is the resistor used for programming the output current. C3 is the output filter capacitor. C1 and C2 are the storage capacitors of the internal charge pump circuit. A logic high at pin 5 will enable the IC and a logic low on the same pin will drive the IC into shutdown mode.

In the shutdown mode, the quiescent current is almost equal to zero. With the used value of R1, the LED current per channel will be 25mA. When powered up the CAT6063 operates in 1X mode i.e, the output voltage will be equal to the input voltage. If this output voltage is enough to regulate the current through all LEDs, the IC remains 1X mode.

If the output voltage is not sufficient enough to regulate the desired current through the LEDs, the device automatically switches to the 1.5X mode where the output voltage is 1.5 times the input voltage. This process is repeated when ever the IC is powered up or awaken from shutdown mode.

Selection of R1 is shown in the table below.

LED current (mA)	R1 (kilo ohm)
1	649
5	287
10	102
15	49.9
20	32.4
25	23.7
30	15.4

Notes.

CAT6063 is not suitable for resistive loads.
Unused LED output channels must be connected to Vout pin. They cannot be left floating.
All capacitors are ceramic capacitors.
Dimming of the LEds can be achieved by using a DC voltage for setting the pin4 (RSET) current or by driving the pin5 (EN) using a PWM signal.
There is an exposed pad beneath the IC and it should soldered to the ground plane of the PCB for improved thermal performance.
Supply voltage should not exceed 6V DC.
Total output current should not exceed 120mA.

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6V Ultra Bright LED Chaser

This is a spectacular but completely useless project. It lights Ultra-Bright LEDs in a sequence and each LED flashes brightly very briefly. The LEDs light-up going around and around since they are mounted in a circle (on a CD), then they pause before chasing again. The very brief flash of each LED (15ms) and the pauses (1 second) reduce the average current so the battery should last a long time.

 

For user convenience, this project has a stepper speed control and a brightness control. At slower speeds and/or reduced brightness, the battery’s life is extended considerably.

At full brightness, the LEDs flash extremely brightly. More than one of this project grouped together occasionally synchronize, lighting the whole room for a moment.

Operation

At maximum speed, the LEDs don’t appear to flash, instead they appear to move from one lighted one to the next, around and around. They rotate completely for 4 rotations in two seconds, and then turn off for a one second pause then repeat the sequence. At a lower speed, the number of rotations before the pause is less. It will do three rotations, two or even only one rotation at its slowest speed. A sequence of rotations starts with LED #2 and end with LED #9. 

Specifications

Battery: Four AA alkaline cells.
Battery life:
                        Minimum speed and brightness              2.3 years
                        Medium speed and brightness                 1 year
                        Minimum speed, maximum brightness   4.1 months
                        Maximum speed and brightness              3.8 weeks

Brightness: controlled with Pulse width Modulation, from off to extremely bright (4000mcd).
Stepper speed: 2 LEDs/sec to 2 revolutions/sec.
Pulse Width Modulation frequency: 3.9KHz.
LED current: 24mA pulses.
LED voltage drop: 3.2V at 24mA. Blue, green and white Ultra-Bright LEDs are suitable.
Minimum battery voltage:
                         <3V, oscillators do not run.
                         3V, LEDs are very dim.
                         4V, LEDs reach almost full brightness.
Radio interference: none.

 

Circuit Description

• The CD74HC4017N high-speed Cmos IC is rated for a maximum supply voltage of 7V. It is rated for a maximum continuous output current of 25mA. In this project, the maximum supply voltage is 6.4V with brand new battery cells and the 24mA output current is so brief that the IC runs cool.
• The MC14584BCP* IC (Motorola) is an ordinary “4XXX series” 3V to 18V Cmos IC, with a very low operating current and low output current. Its extremely high input resistance allows this project to use high value resistors for its timers and oscillators, for low supply current. Its 6 inverters are Schmitt triggers for simple oscillators and very quick switching.
• IC2 is a 10 stage Johnson counter/decoder. On the rising edge of each clock pulse its outputs step one-at-a-time in sequence. It drives the anode of each conducting LED toward the positive supply.
• IC1 pins 1 and 2 is a Schmitt trigger oscillator with C3 and C4 paralleled for a very low frequency. R1 and R2 control its frequency and the diodes with R3 combine with the capacitors to produce the 15mS on time for the LEDs.
• IC1 pins 5 and 6 is the brightness Pulse Width Modulation oscillator. The pot R7 with the associated diodes and resistors allow it to change the duty-cycle of its output for PWM brightness control. It drives the transistor.
• IC1 pins 3 and 4 is an inverter. It takes the low time (LEDs off) from the clock oscillator, inverts it to a high and shuts-off the brightness oscillator through diode D6.
• IC1 pins 11 and 10 is a sample-and-hold stage. It takes a sample of the pulse driving LED #9 though D3 and R4 and charges C5 in steps. At maximum speed it takes 4 steps for C5 to charge to the Schmitt switching threshold voltage. R5 and D5 slowly discharge C5 for the pause time.
• IC1 pins 13 and 12 is an inverter that resets the counter/decoder and shuts-off the clock oscillator through D4, during the pause time.
• IC1 pins 9 and 8 is not used and is shut-off by grounding its input.
• T1 is the PWM switching transistor. R9 limits the maximum LED current to 24mA.

Construction

The 10 LEDs mount on a Compact-Disc which is glued to a plastic box with contact cement. The box houses the Veroboard circuit in its lower main part with the battery holders on its lid. Multiconductor ribbon cable joins the LEDs to the circuit. The pots mount on the sides of the box.

If you turn it down each night, its current is so low an on-off switch isn’t needed.

Parts List

1 IC1 MC14584BCP (Motorola) * Ordinary Cmos hex Schmitt trigger inverters
1 IC2 CD74HC4017N High-speed Cmos decade counter/decoder
1 T1 2N3904 or 2N4401 NPN transistor
8 D1 to D8 1N4148 or 1N914 Diodes
10 LEDs Blue, green or white Ultra-Bright LEDs with Vf = 3.2V or less at 20mA
1 R1 100K 1/4W resistor
1 R2 1M Linear-taper potentiometer
1 R3 33K 1/4W resistor
1 R4 2.2M 1/4W resistor
1 R5 22M 1/4W resistor
1 R6 47K 1/4W resistor
1 R7 1M Audio-taper (logarithmic) potentiometer
1 R8 1.8K 1/4W resistor
1 R9 68 ohms 1/4W resistor

1 C1 100uF/16V Electrolytic capacitor
1 C2 0.1uF/50V Ceramic capacitor
2 C4 and C4 1uF/63V Metalized poly capacitor
1 C5 470nF Metalized poly capacitor
2 C6 and C7 1nF Metalized poly capacitor
 

* A CD74C14 can also be used for IC1 but R4 = 1M, R5 = 10M, C3 and C5 = 330nF, C4 = 470nF.

A 3V LED Chaser project also works well with these changed parts but using a CD74HC14N for IC1.
In addition to these changes, R8 = 680 ohms and R9 = 22 ohms. I built one using low-voltage (1.8V at 20mA) orange Ultra-Bright LEDs. The orange one looks good beside the green one.

Attachments: 6V LED Ultra-Bright Chaser schematic, Veroboard layout and 3 pictures.

I wish I knew how to take a slow picture with my son’s digital camera, so all the LEDs would be lighted, and if I moved it would make nice lighted smears in the picture.
 

Photos

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A Simple yet Effective LED Strobe Light Circuit Explained

You might be quite familiar with strobe lights and should have seen them pretty commonly in parties and discotheques. Although these devices use laser lighta for the generation of the required strobe effect, using high bright LEDs can also be a good alternative, if many of are included. Here we discuss a very simple yet very effective LED strobe light circuit which is in fact more innovative than its commercial counterparts as it produces a chasing effect to lights while implementing the strobing effect simultaneously.

Image Credit - http://www.dinodirect.com/stage-effects-strobe-light-led-ktv-home-decorative-lighting-four-layers.html

Circuit Description:

The circuit is highly innovative and versatile, it actually can be used in many different applications, like in toys, decoration items, as party lights, and in avionics for displaying warning signals from the airplane (tail light probably).

The circuit utilizes the popular IC 4017 for generating the basic chasing or sequencing output through its outputs.

However the above chasing effect becomes a very primary application of the IC and here we are not looking for just a chasing effect, rather we are interested in the strobing pattern which is induced in the circuit by forcing the outputs of the 4017 IC to flash or blink rapidly as it sequences the lights.

To make the IC output strobe, we introduce another IC 4049 and integrate it to the LEDs in the circuit. The IC 4049 basically consists of 6 NOT gate. 

Here two of them are used and configured as an oscillator. Two of the gates are used buffers for facilitating better grounding effect to the LEDs, while the remaining two are used as another oscillator for driving the IC 4017 clock input.

The strobing oscillator and the clocking oscillator can be varied discretely through the respective pots for creating user defined intriguing LED strobe effects.

The LEDs common cathode termination is not connected to its usual position, i.e. to the ground; rather it’s connected to the output of the buffer NOT gates.

The oscillator from the 4049 IC transmits; rapid high and low logic pulses to the buffers which carry forward the response to the LED cathode. When the buffer out is high the LEDs remain shut off during that instant.

However the moment the buffer outputs go low, the LEDs light up and flash rapidly while sequencing, as the LED cathodes now find the ground path through the buffer low output.

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Automatic LED Emergency Light Circuit

This is one of the most cost effective (cheap) and simple emergency light circuit developed for CircuitsToday – This is an automatic emergency lamp with day light sensing, means it senses darkness/night and turns ON automatically. Similarly it senses day light and turns OFF automatically.

A simple emergency lamp which does not require any special equipment; even a multimeter to assemble and use. Any individual who can do a good quality soldering must be able to build this circuit successfully. This can be easily accommodated in the defunct two 6 watt tube National Emergency Lamp or any PL tube type emergency lamp. The difference will be in the working; it will work non stop for more than 8 hours. Deep discharge is taken care by the LED characteristic and over charge protection is taken care by the fixed voltage regulator.This uses a simple 3Pin fixed regulator which has a built in current limiting circuit. The only required adjustment is the preset which has to be set to ensure the LEDs just light up (it should be left at that position). The 5mm LDR is just mounted on top of the emergency light as shown in the photograph. LDR is used to avoid it lighting up during day time or when the room lights are ON. 2 LEDs are used in series; the dropping resistance is avoided and 2 LEDs light up with current that is required for a single LED,  by which energy is saved to a great extent.

Circuit diagram :

 

Simple Emergency Light Circuit Diagram

Note:

This circuit is developed by Mr.Seetharaman for readers of CircuitsToday. This particular circuit has been kept so simple for people who has limited access to components or in other words this is an emergency light that you can build with minimum components. In addition to circuit diagram, He has shared photographs of the prototype he made in National emergency light and a PCB design.

Source :www.circuitstoday.com

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