MAX8678 Maxim Integrated Products, MAX8678 Datasheet - Page 6

• Manufacturer Part Number: MAX8678
• Description: White LED Charge Pump
• Manufacturer: Maxim Integrated Products

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White LED Charge Pump with
1.1W Audio Amplifier
6
(V
IN
_______________________________________________________________________________________
9–12
= 3.2V, R
PIN
13
14
15
16
—
1
2
3
4
5
6
7
8
V
ENLED
L
I
LED1–LED4
LED
= 8Ω, T
ENAMP
ENLED
NAME
OUT+
OUT-
GND
BIAS
NEG
A+
C+
EP
IN
A-
C-
LED SINGLE-WIRE PULSE DIMMING
A
= +25°C, unless otherwise noted.)
Analog Supply-Voltage Input. The input voltage range is 2.7V to 5.5V. Connect a 4.7µF ceramic
capacitor from IN to GND as close as possible to the IC. IN is high impedance during shutdown.
Ground. Connect GND to the system ground plane. Do not connect GND to the exposed paddle.
Noninverting Differential Audio Input
Inverting Differential Audio Input
Amplifier Enable and Gain Control. ENAMP is a serial-pulse interface logic input to control on/off and
gain settings of the audio amplifier.
Audio Amplifier Positive Output
Audio Amplifier Negative Output
DC Bias Bypass. Connect a 0.1µF ceramic capacitor from BIAS to GND as close as possible to the IC.
LED Current Regulators. Current flowing into LED_ is regulated to the current programmed by the
serial-pulse interface. Connect LED_ to the cathodes of the corresponding external LEDs. LED_ is high
impedance during shutdown. If unused, connect LED_ to IN to disable the regulator.
Charge-Pump Negative Output. Connect a 1µF ceramic capacitor from NEG to GND. In shutdown, an
internal 10kΩ resistor pulls NEG to GND.
Transfer Capacitor Negative Connection. Connect a 1µF ceramic capacitor from C+ to C-.
Transfer Capacitor Positive Connection. Connect a 1µF ceramic capacitor from C+ to C-.
LED Enable and Dimming Control. ENLED is a serial-pulse interface logic input to control on/off and
dimming of the LED regulators.
Exposed Paddle. Connect the exposed paddle to NEG directly under the IC.
200ms/div
MAX8678 toc16
Typical Operating Characteristics (continued)
5V/div
20mA/div
(TOTAL)
FUNCTION
I
LED
V
I
IN
IN
3.8V
LINE TRANSIENT WITH MODE
TRANSITION
3.4V
200μs/div
4 LEDs AT 24mA EACH
3.8V
Pin Description
MAX8678 toc17
1V/div
100mA/div
200mA/div