FA5626 FUJI [Fuji Electric], FA5626 Datasheet - Page 26

• Manufacturer Part Number: FA5626
• Description: Fuji Switching Power Supply Control IC
• Manufacturer: FUJI [Fuji Electric]

(10) Prevention of malfunction due to negative
If large negative voltage is applied to each pin of the IC, the
parasitic element within the IC may be actuated, thus
causing malfunction to occur. Be sure to maintain the
voltage to be applied to each pin within the maximum
absolute ratings.
(11) Loss calculation
To use the IC within its ratings, the loss of the IC may have
to be found. However, it is not feasible to measure loss
directly. The following is an example of finding a rough
value of loss by calculation.
The rough value of the total loss of the IC, Pd, can be
calculated using the following expression:
A rough value can be found using the above expression,
and the total loss found by the calculation, Pd, is slightly
larger than the actual value.
Be sure to take into consideration that each characteristic
value varies depending on temperatures and other factors.
Example:
When the VH pin is connected to a half-wave rectifier circuit
with 100VAC input, the average voltage to be applied to the
VH pin is calculated to be approximately 45V, and the
average current to be fed to the VH pin is approximately
130A;.
Furthermore, assuming that Tj = 25C, VCC = 18V, and Qg
= 80nC, and based on
calculated as follows:
AN-071E Rev.1.2
April-2011
where,
VVH: voltage to be applied to the VH pin,
IHrun: current fed to the VH pin during operation,
VCC: power voltage,
ICCop1: Consumption current of the IC
Qg: electrical charge to be input to the MOSFET gate
used, and
Fsw: switching frequency.
Pd≒VCC × (ICCop1 + Qg × fsw) + VVH × IHrun
IHrun=100uA (typ.)
ICCop1=1.4mA (typ.)
fsw=65kHz (typ.)
the loss of the IC having standard characteristics can be
Pd≒18V × (1.4mA + 80nC × 65kHz) + 45V × 100uA
≒ 123 mW
Fuji Electric Co., Ltd.
potential of the pin
FA5626
26
http://www.fujielectric.co.jp/products/semiconductor/