# Can I substitute a different mosfet instead of irlz44n?

#### bigjoncoop

Joined Feb 1, 2019
154

#### Alec_t

Joined Sep 17, 2013
11,979
Your schematic is too small to read.

#### jpanhalt

Joined Jan 18, 2008
11,088
Of the two choices you offer, the AOD4144 is probably the better choice as it is turned on at 4.5V; the SW630 is not. Only problem with the former is its Vds is limited to 30 V rather than the 60 V of the IRLZ44.

What is the maximum voltage it will be switching?

#### bigjoncoop

Joined Feb 1, 2019
154
Of the two choices you offer, the AOD4144 is probably the better choice as it is turned on at 4.5V; the SW630 is not. Only problem with the former is its Vds is limited to 30 V rather than the 60 V of the IRLZ44.

What is the maximum voltage it will be switching?

4.2v.. Only one 18650 cell

#### jpanhalt

Joined Jan 18, 2008
11,088
No problem then.

#### bigjoncoop

Joined Feb 1, 2019
154
No problem then.
Okay. Thank you so much for your quick response. I really appreciate it.

What are the most critical characteristics / values of a mosfet when trying to find a equivalent mosfet to substitute another?.

I'm assuming first of all is, N-Channel, P-channel, NPN etc...

#### bassbindevil

Joined Jan 23, 2014
150
Not an expert, but...
N or P channel
whether it will turn on full with a logic-level gate voltage.
max current
max voltage
Rdson: how low the resistance is when turned on

The first two can potentially be worked around by changing between high and low-side switching, and finding a way to drive the gate with something like 10 volts. Increasing current and reducing Rdson can be achieved by paralleling more devices, but that will also increase gate capacitance, which can affect switching time.

#### ci139

Joined Jul 11, 2016
1,696
i had made a comparison chart for basic-simple characteristics previously , including ...
• Channel type / P , N
• Technology / a physical construction/principle
• U.DS (V)
• I.D (A)
• P (W)
• R.(DS)ON (mΩ)
• T.j.Max (°C)
• I.D(estimated!) 100°C (A)
• I.D(while specified) 100°C (A)
• I.D 25°C (A)
• I.DM Pulsed (A)
• Q.g (nC) -- total gate charge
• dt ON (ns) -- ON delay
• t Rise (ns) -- rise time
• dt OFF (ns) -- OFF delay
• t Fall (ns) -- fall time
• dt Up (ns) -- dt ON + t Rise
• dt Dn (ns) -- dt OFF + t Fall
• f.pk 1:1 (?50%) (MHz)
• f.duty 1.5% (kHz)
• Vth (V) -- threshold voltage
• +
• SOA diagrams -- safe operating area/conditions

about : AN11158.pdf - Understanding power MOSFET data sheet parameters
better : Infineon-MOSFET_OptiMOS_datasheet_explanation-AN-v01_00-EN

#### peterdeco

Joined Oct 8, 2019
327
We sub IRLZ44N with STP55NF06L without any problems.

#### ci139

Joined Jul 11, 2016
1,696
AOD4144 n channel
SW630 N channel
AOD4144 SDMOSTM trench technology -- low voltage (30V) have a lower R(DS)ON 14mΩ - thus - a higher possible drain current 43A @ 100°C
SW630 advanced VDMOS technology -- high voltge (200V) devices have usually and a higher channel ON resistance 400mΩ - thus - a lower allowed draincurrent 6.8A @ 100°C

AOD4144 -- gate charge 28nC , power limit 2.3W , peak current 110A , td.on+t.rise : (7+10 ns) , dt.off+t.fall : (22+5 ns) , Vth 1.2 ... 2.4 V
SW630 -- gate charge 27nC , power limit 72W , peak current 36A , td.on+t.rise : (40+140 ns) , dt.off+t.fall : (150+140 ns) , Vth 2 ... 4 V

* below Vth the mosfet practically does not conduct thus -- won't dissipate any power as $$P=U·I\ ,\ P=Lim_{I→0}\ U·I=0$$ ← also important to know is → $$I_{D}$$ versus $$V_{GS}$$ / versus $$V_{DS}$$ -- e.g. -- how much gate voltage to apply and what should be your power supply voltage to reach up your desired drain current

** the rise and fall times are not so essential if you don't go high speed × high efficiency switching

*** the channel on resistances are not so critical if you won't pass high currents through your device -- e.g. -- currents that would cause a considerable power loss on your mosfet . . . ← if such has significance in a context of the rest of the circuit . . .

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