MAX16816 Datasheet, PDF (24/33 Pages) Maxim Integrated Products – Programmable Switch-Mode LED Driver with Analog-Controlled PWM Dimming

Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
Careful PCB layout is critical to achieve low switching
losses and clean, stable operation. Use a multilayer
board whenever possible for better noise performance
and power dissipation. Follow these guidelines for
good PCB layout:
• Use a large copper plane under the MAX16816
package. Ensure that all heat-dissipating compo-
nents have adequate cooling. Connect the
exposed pad of the device to the ground plane.
• Isolate the power components and high current
paths from sensitive analog circuitry.
• Keep the high-current paths short, especially at the
ground terminals. This practice is essential for sta-
ble, jitter-free operation. Keep switching loops short.
• Connect AGND, SGND, and QGND to a ground
plane. Ensure a low-impedance connection
between all ground points.
• Keep the power traces and load connections
short. This practice is essential for high efficiency.
Use thick copper PCBs (2oz vs. 1oz) to enhance
full-load efficiency.
• Ensure that the feedback connection to FB is short
and direct.
• Route high-speed switching nodes away from the
sensitive analog areas.
• To prevent discharge of the compensation capaci-
tors, C₁ and C₂, during the off-time of the dimming
cycle, ensure that the PCB area close to these
components has extremely low leakage.
Discharge of these capacitors due to leakage may
result in degraded dimming performance.
1-Wire Interface
EEPROM implementation uses a 1-Wire communica-
tion method. A 1-Wire net-based system consists of
three main elements: a bus master with controlling
software, the wiring and associated connectors, and
1-Wire devices. Data on the 1-Wire net is transferred
with respect to time slots. For example, the master pulls
the bus low and holds it for 15µs or less to write a logic
‘1’, and holds the bus low for at least 60µs to write a
logic ‘0’. During EEPROM programming the MAX16816
is a 1-Wire slave device only. Data and clock signals
are supplied through FAULT.
MAX16816 1-Wire Function Commands
Table 10 shows the list of 1-Wire function commands
for the MAX16816. Use these commands to start the
programming mode, write to the on-chip EEPROM, and
read EEPROM through the 1-Wire interface.
PASS_CODE_ONE: The PASS_CODE_ONE sequence
is the first code that the MAX16816 must receive from
the master. PASS_CODE_ONE must be received within
the initial 8ms programming window after startup.
PASS_CODE_TWO: The PASS_CODE_TWO sequence
is the second code that the MAX16816 must receive
during the 8ms programming window. The MAX16816
will start searching for PASS_CODE_TWO only after
PASS_CODE_ONE has been received.
EXT_EEM_MODE: The EXT_EEM_MODE command
clears the PASS_CODE_ONE and PASS_CODE_TWO
verification register. Use this command to exit program-
ming mode.
SET_WRITE_EE: The SET_WRITE_EE command is the
write all command for the MAX16816. When the device
detects the SET_WRITE_EE command the write
Table 10. MAX16816 1-Wire Function Commands
COMMAND
PASS_CODE_ONE
PASS_CODE_TWO
EXT_EEM_MODE
SET_WRITE_EE
SET_WRITE_SCH
SET_READ_SCH
D7
0
0
0
0
ADD
0
D6
0
0
0
0
ADD
0
D5
1
0
0
0
ADD
0
DATA BIT CODE
D4
D3
0
1
0
1
0
0
0
0
ADD
DATA
0
0
D2
0
0
0
1
DATA
1
D1
0
0
0
0
DATA
1
D0
1
1
1
0
DATA
0
HEX
CODE
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