MB39A214APFT-G-JNERE1 Datasheet, PDF (31/56 Pages) Fujitsu Component Limited. – 2ch DC/DC converter IC with PFM/ PWM synchronous rectification

MB39A214A
Power dissipation and the thermal design
IC's loss increases, if IC is used under the high power supply voltage, high switching frequency, high load
and high temperature. The IC internal loss can be calculated by the following formula.
P_IC = V_CC ¯ (I_CC + Q_{G_Total1} ¯ f_OSC1 + Q_{G_Total2} ¯ f_OSC2)
P_IC
: IC internal loss [W]
V_CC : Power supply voltage (V_IN) [V]
I_CC : Power supply current [A] (2 mA Max)
Q_{G_Total1} : Total quantity of charge for the high-side FET and the low-side FET of each CH1 [C]
Q_{G_Total2} : Total quantity of charge for the high-side FET and the low-side FET of each CH2 [C]
f_OSC1 : CH1 switching frequency [Hz]
f_OSC2 : CH2 switching frequency [Hz]
Calculate junction temperature (Tj) by the following formula.
Tj = Ta + θja ¯ P_IC
Tj : Junction temperature [°C] (+ 125°C Max)
Ta : Ambient temperature [°C]
θja : TSSOP-24P Package thermal resistance (+ 78°C /W)
P_IC : IC internal loss [W]
Handling of the pins when using a single channel
Although this device is a 2-channel DC/DC converter control IC, it is also able to be used as a 1-channel
DC/DC converter by handling the pins of the unused channel as shown in the following diagram.
VOUTx
FBx
CSx
ILIMx
ENx
LXx
BSTx
DRVHx
DRVLx
“Open”
“Open”
“Open”
Note: x is the unused channel number.
DS405-00007-1v0-E
31