Programmable 7 channel dual string LED
driver IC powered by single cell Lithium-Ion cells
Linear Technology has released the LTC3675, a digitally
programmable multioutput power supply plus dual string LED
driver IC for single cell Lithium-Ion/Polymer cell powered
systems. The device features seven independent rails, I2C
control, flexible sequencing and fault monitoring. The LTC3675
contains four high efficiency synchronous step-down regulators,
a high current/high efficiency buck-boost regulator, a synchronous
boost regulator, a dual-string 40V-LED driver and an always-on
LDO. Pushbutton ON/OFF/RESET control, precision enable inputs
and a power-on reset output provide power-up sequencing.
The LTC3675's I2C interface provides complete regulator
control, status reporting and a maskable interrupt output.
Quiescent current is 16uA with all DC/DCs off to maximize
battery run time.
The LTC3675's four constant frequency current-mode buck
switching regulators are internally compensated, providing
up to 1A, 1A, 500mA and 500mA output currents, respectively,
with complete I2C control. Further, the buck power stages
can be paralleled to deliver up to twice the output current
with a single inductor. The buck regulators can operate
in two different modes. In pulse-skipping mode, the regulator
will skip pulses at light loads, but will operate at a constant
frequency of 2.25MHz at higher loads. In Burst Mode operation,
the regulator will burst at light loads for best efficiency,
and at higher loads will operate in constant frequency PWM
mode for lowest noise performance. I2C may be used to control
the device, enabling mode of operation, feedback regulation
voltage and switch slew rate. The bucks have forward and
reverse current limiting, soft-start to limit inrush current
during start-up, short-circuit protection and slew rate
control for lower radiated EMI.
The LTC3675's buck-boost regulator is a 2.25MHz voltage
mode regulator designed to deliver up to 1A load current
for a typical programmed output voltage of 3.3V. The regulator
can be enabled via its enable pin or via I2C. The mode of
operation (Burst Mode or PWM), feedback regulation voltage
and switch slew rate can all be controlled via I2C. The
buck-boost regulator also features forward current limiting,
soft-start to limit inrush current during start-up, short-circuit
protection and slew rate control for lower radiated EMI.
The LTC3675's boost regulator is designed to deliver up
to 1A load current for a programmed output voltage of up
to 5V. Boost DC/DC enable, mode of operation (Burst Mode
or PWM), feedback regulation voltage and switch slew rate
can all be controlled via I2C. The boost regulator has forward
and reverse current limiting, soft start to limit inrush
current during start-up, short-circuit protection, slew
rate control for lower radiated EMI and true output disconnect
when in shutdown.
The LTC3675's constant frequency, current mode 40V LED
driver can regulate up to 25mA of current through each of
two series 10-LED strings. LED enable, 60dB brightness control
and up/down gradation are programmed using I2C. The LED
driver can be configured as a general purpose high voltage
boost converter with a 1.6A (typ) switch current limit.
Given its high duty cycle operation, it can boost from below
3V to up to 40V output at 55mA.
Package: 0.75mm 44-pin 4mm x 7mm QFN
Operating temperature range: -40°C to +125°C
Price: E grade is priced at US$5.05 each for 1000
unit quantities
Availability: Now
For more information visit: www.linear.com
