Rainbow Electronics MAX6948B - Manual

_______________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
High-Efficiency PWM LED Driver with Boost
Converter and Five Constant-Current GPIO Ports MAX6948B
General Description
The MAX6948B general-purpose input/output (GPIO)
peripheral drives a series string of white LEDs (WLEDs),
and contains up to five general-purpose input/output
(GPIO) ports to drive additional LEDs.
The integrated 2MHz boost converter minimizes the size
and cost of external components and supplies 30mA of
load current at up to 28V. The converter is stable under
all load conditions from 5V up to 28V and includes
open-circuit detection to prevent damage to the IC. An
I
2 C-programmable 10-bit pulse-width modulation (PWM)
signal enables 1024 levels of WLED intensity.
The five GPIO ports function as logic inputs, open-
drain logic outputs, or constant-current sinks in any
combination. Ports withstand 5.5V independent of the
MAX6948B’s supply voltage. Two of the ports drive addi-
tional LEDs up to 30mA/port, while the other three ports
drive LEDs at up to 10mA/port. The MAX6948B features
shutdown and standby modes for low-power dissipa-
tion. The constant-current drivers contain programmable
PWM outputs and allow staggering to reduce the input
peak-current requirements. The I/O ports also feature
ramp-up and ramp-down controls.
The MAX6948B features a single input to select from four
I
2 C slave addresses. Programming and functionality for
the five GPIO ports is identical to the MAX6946/MAX6947
I/O expanders.
The MAX6948B is available in a 25-bump (2.31mm x
2.31mm) WLP package for cell phones, PDAs, and
other portable consumer electronic applications. The
MAX6948B operates over the -40NC to +105NC tempera-
ture range.
Applications
LED Backlighting for LCDs
Cell Phones
PDAs
Handheld Games
Portable Consumer Electronics
Features
S 28V Step-Up DC-DC Converter with Integrated
nMOS Power Switch
S Built-In 10-Bit PWM Control for Improved Efficiency
S
No Discharge Path During PWM Off Period for
Increased Battery Life
S Fixed 2MHz Switching for Smaller Components
Drives up to 6 Series WLEDs
S ±8kV Human Body Model (HBM) ESD Protection
for GPIOs and Boost-Converter Output
S Five Open-Drain GPIOs Capable of Constant-
Current LED Drive with Individual 8-Bit PWM
Intensity Control
S 2.7V to 5V Power-Supply Operation
S
400kbps, 5.5V Tolerant I 2 C Interface
S Four I 2 C Slave Address Choices
S RST Input Clears Serial Interface and Exits
Shutdown (Reset-Run Option)
S
Small (2.31mm x 2.31mm) WLP Package
19-4935; Rev 0; 9/09
Ordering Information
+Denotes a lead(Pb)-free/RoHS-compliant package.
Typical Operating Circuit
EVALUATION KIT
AVAILABLE
NOTE: R B = 0.2V/I LED = 0.2V/0.03A = 6.7I.
2.7V TO 5.0V
1.7V TO V+
LX
V+
SCL
SDA
RST
SCL
SDA
RST
V DD
COMP
AD0
GND
OUT
PGND
FB
LEDSW
B
G
R
P0
P1
P2
P3
P4
0.22FF
R B
10 µH
0.1FF
47nF
V EXT
MAX6948B
2.2FF
PART TEMP RANGE PIN-PACKAGE
MAX6948BGWA+ -40NC to +105NC 25 WLP