AT1310 Datasheet, PDF (8/11 Pages) Aimtron Technology – MicroPower Charge Pump Converter

Application Information
AT1310
Preliminary Product Information
MicroPower Charge Pump Converter
1. Capacitor Selection
It is very important to select the capacitors C_IN, C_OUT and C_FLY because they will affect turn
on time, output ripple and transient performance. Ceramic capacitors offer many advantages
over other tantalum and aluminum electrolytic counterparts. In general, the capacitors can
be used 10µF for C_IN and C_OUT, and 1µF for C_FLY under maximum output load conditions.
Lower values for CIN, COUT and CFLY may be utilized for light load current applications.
Large ceramic capacitors are typically composed of X7R, X5R, Z5U or Y5V dielectric
materials. If Y5V and Z5U are selected for used with the charge pump, the nominal value
should be doubled to compensated for the capacitor tolerance which can vary more than
±50% over operating temperature range. X7R and X5R dielectrics are much more desirable.
The temperature tolerance of X7R dielectric is better than ±15% .
2. Charge Pump Efficiency
The AT1310 is a regulated output voltage charger pump converter. The Efficiency can be
defined as a linear voltage regulator with an effective output voltage that is equal to two
times the input voltage. The expression to define the ideal efficiency can be shown as:
η = ^POUT = ^{VOUT × IOUT} = ^VOUT
P_IN V_IN × 2I_OUT 2 ×V_IN
Refer to the Typical Characteristics section for measured plots of efficiency versus input
voltage and output load current for the given charge pump output voltage options.
3. Layout Guideline
As a general rule for charge pump boost converters, all external capacitors should be located
as closed as possible to the device package with minimum length trace connections. A local
component side ground plane is recommended. If this is not possible due to the layout
limitations, assure good ground connections by the use of large or multiple PCB via’s.
Refer to the following AT1310 evaluation board layout. ( Application Circuit Fig3.)
7F, No.9, Park Avenue. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: [phone] Fax: [phone]
WWW: http://www.aimtron.com.tw
2/8/2006 REV:1.1
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