MAX1577YETA+T Maxim Integrated Products, MAX1577YETA+T Datasheet - Page 10

• Manufacturer Part Number: MAX1577YETA+T
• Description: IC LED DRIVR BCKLGT FLASH 8-TDFN
• Manufacturer: Maxim Integrated Products
• Type: Backlight, Flash, Movier

Specifications of MAX1577YETA+T

• Topology: Linear (LDO), PWM, Switched Capacitor (Charge Pump)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: Backlight, Flash/Torch
• Type - Secondary: RGB, White LED
• Frequency: 800kHz ~ 1.25MHz
• Voltage - Supply: 2.7 V ~ 5.5 V
• Voltage - Output: 3.4V, 4.6V, 5.1V
• Mounting Type: Surface Mount
• Package / Case: 8-TDFN Exposed Pad
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 800mA
• Internal Switch(s): Yes
• Efficiency: 92%
• Function: Step Up, Step Down
• Output Voltage: 3.4 V, 4.6 V, 5.1 V
• Output Current: 1200 mA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

1.2A White LED Regulating Charge Pump for
Camera Flashes and Movie Lights
(Figure 2), the ballast resistors must be small enough to
prevent triggering the overvoltage protection:
where I
the forward voltage of the LED at I
larger values of R
ing but also increase the input voltage where the 2x
charge pump makes the transition to the more efficient
1x LDO mode.
When using voltage regulation (Figure 3), select the
ballast resistors based on the full brightness setting as
follows:
With EN1 high and EN2 high:
The LED current at the dimmed settings are calculated
as follows:
with EN1 high and EN2 low:
with EN1 low and EN2 high:
10
______________________________________________________________________________________
LED
is the current through each LED and V
R
R
I
I
LED
LED
BALLAST
BALLAST
BALLAST
= (4.6V - V
= (3.4V - V
< (5.1V - V
= (5.1V - V
improve LED-to-LED match-
F
F
) / R
) / R
BALLAST
BALLAST
F
F
LED
) / I
) / I
. Within this limit,
LED
LED
F
is
Note that V
manufacturers provide a plot of forward voltage (V
forward current (I
The MAX1577Y/MAX1577Z are high-frequency
switched-capacitor regulators. For best circuit perfor-
mance, use a solid ground plane and place C
and C1 as close to the IC as possible. Connect the
exposed pad to GND directly under the IC and allow suf-
ficient copper area for cooling. Refer to the MAX1577Z
evaluation kit for an example PC board layout.
TRANSISTOR COUNT: 2482
PROCESS: BiCMOS
F
varies as a function of I
LED
PC Board Layout and Routing
) in the LED data sheet.
Chip Information
LED
. Typically, LED
IN
, C
F
OUT
) vs.
,