MAX8821 MAXIM [Maxim Integrated Products], MAX8821 Datasheet - Page 27

• Manufacturer Part Number: MAX8821
• Description: White LED Charge Pump with Mono Class D Audio Amp and Dual LDO
• Manufacturer: MAXIM [Maxim Integrated Products]

Table 16. PUMP_CNTL (Address 0x0E)
Note: Defaults in bold italics.
B1, B0
B7–B3
TOP VIEW
BIT
B2
PGND1
C2N
C1N
C2P
C1P
IN1
IN3
N/A, do not use
TEMP_DR
PUMP_CNTL [1:0]
White LED Charge Pump with Mono Class D
22
23
24
25
26
27
28
+
NAME
21
1
______________________________________________________________________________________
20
2
EP = EXPOSED PADDLE
MAX8821ETI+
19
3
18
4
Pin Configuration
CODE
00
01
10
11
0
1
17
5
16
6
Temperature
derating disabled.
Temperature derating
enabled.
Charge pump
automatically
changes between
1x/1.5x mode.
Charge pump is
forced into 1.5x mode
regardless of input
voltage.
Charge pump is
forced into 1.5x mode
regardless of input
voltage when audio
amplifier is enabled. If
the amplifier is not
enabled, the charge
pump automatically
switches between 1x
mode and 1.5x mode.
N/A, do not use.
15
7
DESCRIPTION
14
13
12
11
10
9
8
REF
AGND
SDA
SCL
LDO1
LDO2
IN2
Audio Amp and Dual LDO
PCB layout is essential for optimizing performance. Use
large traces for the power-supply inputs and amplifier
outputs to minimize losses due to parasitic trace resis-
tance and to route heat away from the device. To avoid
potential noise to the differential input audio signal and
differential output audio signal, route the negative and
positive traces in parallel. Also, avoid placing any RF or
high-speed data signals in parallel to the audio signals.
In some applications, such as GSM, extra noise reduc-
tion may be needed. To reduce the risk of noise, place
16pF ceramic capacitors from AIN+ to AGND, AIN- to
AGND, OUT+ to AGND, OUT- to AGND, OUT+ to OUT-,
and AIN+ to AIN-.
Proper grounding improves audio performance and
prevents any digital switching noise from coupling into
the audio signal. The Thin QFN package features an
exposed thermal paddle on its undersides. This paddle
lowers the thermal resistance of the package by provid-
ing a direct-heat conduction path from the die to the
PCB. Connect the exposed paddle to AGND directly
under the IC. Refer to the MAX8821 Evaluation Kit for
an example of a PCB layout.
PROCESS: BiCMOS
Applications Information
Chip Information
PCB Layout
27