AP1601M10G-13 Diodes Inc, AP1601M10G-13 Datasheet - Page 9

• Manufacturer Part Number: AP1601M10G-13
• Description: IC BOOST ADJ 1.2A 10MSOP
• Manufacturer: Diodes Inc
• Type: Step-Up (Boost)r

Specifications of AP1601M10G-13

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: Adjustable
• Current - Output: 1.2A
• Frequency - Switching: 100kHz
• Voltage - Input: 1.1 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Functional Description
General Description
AP1601 PFM (pulse frequency modulation) converter IC series
combine a switch mode converter, N-channel power MOSFET,
precision voltage reference, and voltage detector in a single
monolithic device. They offer both extreme low quiescent current,
high efficiency, and very low gate threshold voltage to ensure
start-up with low battery voltage (0.9V typ.). Designed to
maximize battery life in portable products, and minimize
switching losses by only switching as needed service the load.
PFM converters transfer a discrete amount of energy per cycle
and regulate the output voltage by modulating switching
frequency with the constant turn-on time. Switching frequency
depends on load, input voltage, and inductor value, and it can
range up to 100KHz. The SW on resistance is typically 1 to 1.5W
to minimize switch losses. When the output voltage drops, the
error comparator enables 100KHz oscillator that turns on the
MOSFET around 7.5us and 2.5ms off time. Turning on the
MOSFET allows inductor current to ramp up, storing energy in a
magnetic field and when MOSFET turns off that force inductor
current through diode to the output capacitor and load. As the
stored energy is depleted, the current ramp down until the diode
turns off. At this point, inductor may ring due to residual energy
and stray capacitance. The output capacitor stores charge when
current flowing through the diode is high, and release it when
current is low, thereby maintaining a steady voltage across the
load. As the load increases, the output capacitor discharges
faster and the error comparator initiates cycles sooner,
increasing the switching frequency. The maximum duty cycle
ensure adequate time for energy transfer to output during the
second half each cycle. Depending on circuit, PFM converter
can operate in either discontinuous mode or continuous
conduction mode. Continuous conduction mode means that the
inductor current does not ramp to zero during each cycle.
AP1601 Rev. 5
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9 of 12
Diode Selection
Speed, forward drop, and leakage current are the three main
considerations in selecting a rectifier diode. Best performance is
obtained with Schottky rectifier diode, such as 1N5819. Motorola
makes B0520LW in surface mount. For lower output power a
1N4148 can be used although efficiency and start up voltage will
suffer substantially.
Inductor Selection
To operate as an efficient energy transfer element, the inductor must
fulfill three requirements. First, the inductance must be low enough
for the inductor to store adequate energy under the worst case
condition of minimum input voltage and switch ON time. Second, the
inductance must also be high enough so maximum current rating of
AP1601 and inductor are not exceed at the other worst case
condition of maximum input voltage and ON time. Lastly, the
inductor must have sufficiently low DC resistance so excessive
power is not lost as heat in the windings. But unfortunately this is
inversely related to physical size. Minimum and maximum input
voltage, output voltage and output current must be established
before and inductor can be selected.
Capacitor Selection
A poor choice for a output capacitor can result in poor efficiency and
high
inexpensive may have unacceptably poor ESR and ESL. There are
low ESR aluminum capacitors for switch mode DC-DC converters
which work much better than general propose unit. Tantalum
capacitors provide still better performance at more expensive.
OS-CON capacitors have extremely low ESR in a small size. If
capacitance is reduced, output ripple will increase. Most of the input
supply is supplied by the input bypass capacitor. The capacitor
voltage rating should be at least 1.25 times greater than a maximum
input voltage.
output
ripple.
STEP-UP DC/DC CONVERTER
Ordinary
aluminum
FEBRUARY 2009
©
electrolyzers,
AP1601
Diodes Incorporated
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