AIC1610 Datasheet, PDF (11/16 Pages) Analog Intergrations Corporation – HIGH EFFICIENCY SYNCHRONOUS STEP-UP DC/DC CONVERTER

AIC1610/AIC1611
PIN DESCRIPTIONS
PIN 1: FB-
PIN 2: LBI-
PIN 3: LBO-
Connecting to OUT to get +3.3V
output, connecting to GND to get
+5.0V output, or using a resistor
network to set the output voltage
from +1.8V to +5.5V.
Low-battery comparator input. In-
ternally set at +1.23V to trip.
Open-drain low battery comparator
output. Output is low when V_LBI is
<1.23V. LBO is high impedance
during shutdown.
APPLICATION INFORMATION
Overview
AIC1610/AIC1611 series are high efficiency, step-
up DC-DC converters, designed to feature a built-in
synchronous rectifier, which reduces size and cost
by eliminating the need for an external Schottky di-
ode. The start-up voltage of AIC1610/AIC1611 is as
low as 0.8V and it operates with an input voltage
down to 0.7V. Quiescent supply current is only 20µA.
The internal P-MOSFET on-resistance is typically
0.3Ω to improve overall efficiency by minimizing AC
losses. The output voltage can be easily set by two
external resistors from 1.8V to 5.5V, connecting FB
to OUT to get 3.3V, or connecting to GND to get
5.0V. The peak current of the internal switch is fixed
at 1.0A (AIC1610) or 0.65A (AIC1611) for design
flexibility. The current limit of AIC1610 and AIC1611
are 1.0A and 0.65A respectively. The lower current
limit allows the use of a physically smaller inductor
in space-sensitive applications.
PFM Control Scheme
The key feature of the AIC1610 series is a unique
minimum-off-time, constant-on-time, current-limited,
pulse-frequency-modulation (PFM) control scheme
(see BLOCK DIAGRAM) with the ultra-low quies-
PIN 4: REF- 1.23V reference voltage. Bypass
with a 0.1µF capacitor.
PIN 5: SHDN- Shutdown input. High=operating,
low=shutdown.
PIN 6: GND- Ground
PIN 7: LX- N-channel and P-channel power
MOSFET drain.
PIN 8: OUT- Power output. OUT provides boot-
strap power to the IC.
cent current. The peak current of the internal N-
MOSFET power switch can be fixed at 1.0A
(AIC1610) or 0.65A (AIC1611). The switch
frequency depends on either loading condition or
input voltage, and can range up to 500KHz. It is
governed by a pair of one-shots that set a minimum
off-time (1µS) and a maximum on-time (4µS).
Synchronous Rectification
Using the internal synchronous rectifier eliminates
the need for an external Schottky diode. Therefore,
the cost and board space are reduced. During the
cycle of off-time, P-MOSFET turns on and shunts N-
MOSFET. Due to the low turn-on resistance of
MOSFET, synchronous rectifier significantly im-
proves efficiency without an additional external
Schottky diode. Thus, the conversion efficiency can
be as high as 93%.
Reference Voltage
The reference voltage (REF) is nominally 1.23V for
excellent T.C. performance. In addition, REF pin
can source up to 100µA to external circuit with good
load regulation (<10mV). A bypass capacitor of
0.1µF is required for proper operation and good per-
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