MAX8631YETI+ Maxim Integrated Products, MAX8631YETI+ Datasheet - Page 11

• Manufacturer Part Number: MAX8631YETI+
• Description: IC LED DRVR WHITE BCKLGT 28-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Backlight, White LED (Serial Interface)r

Specifications of MAX8631YETI+

• Constant Current: Yes
• Topology: Linear (LDO), Switched Capacitor (Charge Pump)
• Number Of Outputs: 8
• Internal Driver: Yes
• Type - Primary: Backlight, Flash/Torch
• Type - Secondary: White LED
• Frequency: 1MHz
• Voltage - Supply: 2.7 V ~ 5.5 V
• Voltage - Output: 5V
• Mounting Type: Surface Mount
• Package / Case: 28-TQFN Exposed Pad
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 200mA
• Internal Switch(s): Yes
• Efficiency: 85%
• Operating Supply Voltage: 2.7 V to 5.5 V
• Maximum Supply Current: 5.5 mA
• Maximum Power Dissipation: 1666 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX8631X/Y includes a thermal-limit circuit that
shuts down the IC at approximately +160°C. Turn-on
occurs after the IC cools by approximately 20°C.
SETM controls M1–M4 regulation current. Current flow-
ing into M1, M2, M3, and M4 is a multiple of the current
flowing out of SETM:
where K = 230, and R
between SETM and GND (see the Typical Operating
Circuit ).
SETF controls the F1–F4 regulation current. Current
flowing into F1, F2, F3, and F4 is a multiple of the cur-
rent flowing out of SETF.
where N = 690.
For more dimming flexibility or to reduce the number of
control traces, the MAX8631X/Y supports serial pulse
dimming. Connect ENM1 and ENM2 together to enable
single-wire pulse dimming of the main LEDs (or ENF
only for single-wire pulse dimming of the flash LEDs).
See Figure 3. When ENM1 and ENM2 (or ENF) go high
simultaneously, the main (or flash) LEDs are enabled at
full brightness. Each subsequent low-going pulse
Figure 2. ENM_ and ENF Timing Diagram
Table 1. ENM1/ENM2 States
ENM1 = low, ENM2 = low
ENM1 = high, ENM2 = high
ENM1/ENM2 STATES
ENM1 AND ENM2
I
M1
1x/1.5x/2x White LED Charge Pump with Two
I
ENF
I
OR
F1
M_
OR I
= I
= I
SHUTDOWN
F_
M2
Setting the Flash Output Current
F2
Setting the Main Output Current
Applications Information
= I
= I
______________________________________________________________________________________
0
t
M3
SOFT-START
F3
Single-Wire Pulse Dimming
= I
INITIAL t
= I
≥ 200μs
32/32
SETM
F4
M4
HI
BRIGHTNESS
Full brightness
= N x (0.6V / R
= K x (0.6V / R
Shutdown
is the resistor connected
Thermal Shutdown
1
31/32
2
30/32
3
LDOs in 4mm x 4mm Thin QFN
SETF
SETM
29/32
230 x I
CURRENT
M1–M4
500ns TO 250μs
4
)
28/32
0
)
SETM
5
27/32
t
LO
(500ns to 250µs pulse width) reduces the LED current
by 3.125% (1/32), so after one pulse the LED current is
96.9% (or 31/32) x I
current to 0.03125 x I
current back to I
for single-wire pulse dimming. Because soft-start is
longer than the initial t
upon startup (after initial t
sitioning through full brightness.
If dimming control is not required, connect ENM1 to
ENM2 for simple on/off control. Drive both ENM1 and
ENM2 to a logic-level high to turn on the main LEDs.
Drive both ENM1 and ENM2 to a logic-level low to turn
off the main LEDs. ENF is the simple on/off control for
the flash LEDs. Drive ENF to a logic-level high to turn
on the flash LEDs. Drive ENF to a logic-level low to turn
off the flash LEDs. In this case, LED current is set by
the values of R
When driving fewer than 8 LEDs, two different connec-
tion schemes can be used. The first scheme is shown
in Figure 4 where LED drivers are connected together.
This method allows increased current through the LED
and effectively allows total LED current to be I
plied by the number of connected drivers. The second
method of connection is shown in Figure 5 where stan-
dard white LEDs are used and fewer than 8 are con-
nected. This scheme does not alter current through
each LED but ensures that the unused LED driver is
properly disabled.
For LED drivers, input ripple is more important than out-
put ripple. Input ripple is highly dependent on the
source supply’s impedance. Adding a lowpass filter to
the input further reduces input ripple. Alternately,
increasing C
a small increase in footprint. The 1x mode always has
very low input ripple.
≥500ns
27
t
5/32
HI
28
4/32
IN
29
3/32
SETM
to 22µF cuts input ripple in half with only
LED
30
2/32
and R
. Figure 2 shows a timing diagram
LED
Driving Fewer than 8 LEDs
LED
31
HI
1/32
, apply dimming pulses quickly
. The 31st pulse reduces the
. The 32nd pulse sets the LED
HI
SETF
32
32/32
Simple On/Off Control
) to avoid LED current tran-
.
31/32
(2.5ms)
t
SHDN
Input Ripple
SHUTDOWN
LED
multi-
11