MAX8678EVKIT+ Maxim Integrated Products, MAX8678EVKIT+ Datasheet - Page 3

• Manufacturer Part Number: MAX8678EVKIT+
• Description: KIT EVAL FOR MAX8678
• Manufacturer: Maxim Integrated Products

Specifications of MAX8678EVKIT+

• Current - Output / Channel: 24mA
• Outputs And Type: 4, Non-Isolated
• Features: Dimmable, with Mono 1.1W Class AB Audio Amplifier
• Voltage - Input: 2.7 ~ 5.5V
• Utilized Ic / Part: MAX8678
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

The on-board pulse generator provides an easy way to
evaluate the LED dimming and amplifier gain adjust-
ment. The pulse generator outputs the serial-pulse sig-
nals for ENLED and ENAMP. LED D6 indicates when
the LED driver is active and LED D5 indicates when the
audio amplifier is active. Five pushbutton switches
(S1–S5) are used to set the LED brightness and amplifi-
er gain, as shown in Table 2.
The pulse generator is powered from either IN1 or IN2.
To power from IN1, connect pins 1-2 of JU7. This pow-
ers the EV kit from the same supply as the MAX8678,
allowing the EV kit to operate from a single supply. To
power the pulse generator from a separate supply, con-
nect pins 2-3 of JU7 and connect the supply from IN2
to GND2. This is useful when evaluating the quiescent
current of the MAX8678.
To use external pulse generators to control ENLED and
ENAMP, disconnect ENLED and ENAMP from the on-
board pulse generator by removing the shunts from
JU4 and JU5. Remove the shunt from JU7 to discon-
nect power from the on-board pulse generator. The sig-
nals from the external pulse generators are connected
to the pads labeled ENLED and ENAMP. For informa-
tion on the required serial-pulse signal, refer to the
MAX8678 IC data sheet.
Using the on-board pulse generator, press S2 to
increase LED brightness or press S3 to decrease bright-
ness. There are 31 brightness settings and an off setting.
Refer to the MAX8678 IC data sheet for details. Pressing
S1 starts the LED demo, which cycles through a preset
sequence of dimming and flashing. Press S2 or S3 to
Table 2. Pulse-Generator Controls
PUSHBUTTON
S1
S2
S3
S4
S5
Used to activate the LED demo. The MAX8678 EV kit changes the brightness of LED1–LED4 in a predefined
sequence. Press S2 or S3 to stop the demo.
Used to increase the brightness of LED1–LED4. When maximum brightness is reached, an additional press of S2
forces the MAX8678 to enter power-down mode for the LEDs.
Used to decrease the brightness of LED1–LED4. When minimum brightness is reached, an additional press of S3
turns off the MAX8678 LEDs. Pressing S3 when the LEDs are off turns the LEDs on at full brightness.
Used to increase gain of the audio amplifier. When maximum gain is reached, an additional press of S4 turns off
the audio amplifier. Pressing S4 when the audio amplifier is off turns the amplifier on at minimum gain.
Used to decrease gain of the audio amplifier. When minimum gain is reached, an additional press of S3 turns off
the audio amplifier. Pressing S5 when the audio amplifier is off turns the amplifier on at maximum gain.
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Using External Pulse Generators
On-Board Pulse Generator
Detailed Description
LED Driver
MAX8678 Evaluation Kit
cancel the demo. The power-up default setting is off.
Note that the LEDs might flash briefly when power is first
applied, due to the pulse-generator circuit powering up.
To use fewer than four LEDs, connect the square pad
next to any unused LEDs to the IN1 pad.
To connect external LEDs to the MAX8678 EV kit, cut the
trace shorting JU6. Connect the anodes of all the external
LEDs to the IN1 pad. Connect each cathode to one of the
LED outputs (square pads next to D1–D4). If fewer than four
LEDs are used, connect any unused LED output to IN1.
Using the on-board pulse generator, press S4 to
increase the amplifier gain or S5 to reduce the gain. The
gain up/down buttons cycle through off and -9dB to
+18dB in 3dB steps. The power-up default setting is off.
The EV kit has 1µF input filter capacitors installed. To
evaluate without the filter capacitors, short the pins of
JU2 and JU3. If the input bias voltage is out of the
MAX8678’s common-mode input-voltage range, these
jumpers must be open.
JU1 selects between differential or single-ended inputs.
For a differential input, connect the input to the IN+ and
IN- pads. For a single-ended input, connect the input to
IN+ with the signal ground connected to GND1. When
using a single-ended input, the input filter capacitors
must be used (JU2 and JU3 are open).
The MAX8678 EV kit is capable of driving a speaker
with 4Ω or greater impedance. Connect the speaker
across the OUT+ and OUT- pads.
FUNCTION
Evaluating with Fewer than Four LEDs
Differential or Single-Ended Input
Input Filter Capacitors
Using External LEDs
Audio Amplifier
Speaker Output
3