MAX17061AEVKIT+ Maxim Integrated Products, MAX17061AEVKIT+ Datasheet - Page 16

• Manufacturer Part Number: MAX17061AEVKIT+
• Description: Power Management Modules & Development Tools MAX17061A EVAL KIT MAX17061A EVAL KIT
• Manufacturer: Maxim Integrated Products

Specifications of MAX17061AEVKIT+

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8-String White LED Driver with
SMBus for LCD Panel Applications
The MAX17061A uses an internal DPWM signal to per-
form dimming control. The DPWM frequency is specified
by an external resistor connected from FSET pin to GND:
where:
The adjustable range for the FSET resistor, R
from 42kΩ to 464kΩ, corresponding to the DPWM fre-
quency of 200Hz to 2kHz.
The MAX17061A’s dimming control circuit consists of
two interfaces: PWM and SMBus. The block diagram of
these two input interfaces is shown in Figure 4. The
dimming can be performed in three modes: PWM,
SMBus, or DPST. In PWM mode, the brightness is
adjusted by the PWM signal applied to the PWMI pin. In
SMBus mode, the brightness is adjusted by a com-
mand from uplink processor through the 2-wire SMBus.
In DPST mode, the brightness is adjusted by the prod-
uct of the PWM duty cycle and SMBus command value.
This DPWM control provides a dimming range with 8-bit
resolution down to 2.7% and supports Intel DPST to
maximize battery life.
The SMBus interface can be used to adjust the dimming,
as well as shut down the MAX17061A. Before the
MAX17061A receives a turn-on command from the
Figure 4. MAX17061A PWM and SMBus Interface Circuit
16
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= 58509
= 10.638
PWMI
PWMO
SDA
SCL
f
DPWM
Dimming Control Interfaces
DPWM Frequency Setting
R
10
[ ]
9
BUFFER
IDENTIFICATION
0x03
REGISTER
SMBus AND PWM INPUT BLOCK
FSET
A
D
, is
FAULT/STATUS
< = 1
0x02
REGISTER
1
INTERFACE
SMBus
PWM_MD
SMBus, it automatically remains off. In this low-power
state, most of the control circuits are turned off. Even in
PWM dimming mode, only the PWMI interface is used for
brightness control; the MAX17061A cannot run without the
SMBus interface. For sister products without the SMBus
interface, contact MAXIM Integrated Products, Inc.
The MAX17061A includes four registers to monitor and
control brightness, fault status, identification, and oper-
ating mode. The slave address is 0b0101100.
The MAX17061A uses two multiplexers internally to
direct the dimming signal processing (Figure 4). These
two multiplexers are controlled by 2 bits of the device
control register, PWM_SEL, and PWM_MD, respectively.
The PWM_SEL bit selects either the SMBus or the PWM
input to control the brightness. The PWM_MD bit
selects the mode in which the PWM input is to be inter-
preted. Table 2 provides a complete setting of the three
dimming modes (X means don’t care).
In PWM mode, the output LED brightness is solely con-
trolled by the percentage duty cycle of the input signal
to PWMI. In SMBus mode, the input of PWMI has no
effect on the dimming control, and only the SMBus
command to brightness control register adjusts the out-
put brightness. In DPST mode, the overall brightness
level is the normalized product of the SMBus command
setting and PWM input duty cycle. The PWM signal
starts from 100% when operating in DPST mode.
MUX
0x01
CONTROL
REGISTER
DEVICE
Dimming Control Register Descriptions
MULTIPLIER
DIGITAL
PWM_SEL
0x00
BRIGHTNESS
CONTROL
REGISTER
MUX
BACKLIGHT
ON/OFF
SETTING
DPWM