MDC3105LT1G ON Semiconductor, MDC3105LT1G Datasheet - Page 7

• Manufacturer Part Number: MDC3105LT1G
• Description: IC RELAY/DRVR INDUCT LOAD SOT23
• Manufacturer: ON Semiconductor
• Type: Relay/Load Driverr

Specifications of MDC3105LT1G

• Input Type: Non-Inverting
• Number Of Outputs: 1
• Current - Output / Channel: 400mA
• Current - Peak Output: 500mA
• Voltage - Supply: 6V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-3, TO-236-3, Micro3™, SSD3, SST3
• Supply Voltage Max: 6V
• No. Of Outputs: 1
• Output Current: 400mA
• Driver Case Style: SOT-23
• Device Type: Relay
• Filter Terminals: SMD
• No. Of Pins: 3
• Rohs Compliant: Yes
• Leaded Process Compatible: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• On-state Resistance: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: MDC3105LT1GOS; MDC3105LT1GOS; MDC3105LT1GOSTR

allows one to increase a device’s peak power dissipation
rating above the average rating by dividing by the duty cycle
of the repetitive pulse train. Thus, a continuous rating of 200
mW of dissipation is increased to 1.0 W peak for a 20% duty
cycle pulse train. However, this only holds true for pulse
widths which are short compared to the thermal time
constant of the semiconductor device to which they are
applied.
thermal time constant of the device, the peak operating
condition begins to look more like a continuous duty
operating condition over the time duration of the pulse. In
these cases, the peak power dissipation rating cannot be
merely time averaged by dividing the continuous power
rating by the duty cycle of the pulse train. Instead, the
average power rating can only be scaled up a reduced
amount in accordance with the device’s transient thermal
response, so that the device’s max junction temperature is
not exceeded.
transient thermal resistance, r(t) as a function of pulse width
in ms for various pulse train duty cycles as well as for a
single pulse and illustrates this effect. For short pulse widths
near the left side of the chart, r(t), the factor, by which the
continuous duty thermal resistance is multiplied to
determine how much the peak power rating can be increased
above the average power rating, approaches the duty cycle
of the pulse train, which is the expected value. However, as
the pulse width is increased, that factor eventually
approaches 1.0 for all duty cycles indicating that the pulse
width is sufficiently long to appear as a continuous duty
condition to this device. For the MDC3105LT1, this pulse
width is about 100 seconds. At this and larger pulse widths,
the peak power dissipation capability is the same as the
continuous duty power capability.
a specific application, enter the chart with the worst case
pulse condition, that is the max pulse width and max duty
cycle and determine the worst case r(t) for your application.
Then calculate the peak power dissipation allowed by using
the equation,
yields r(t) = 0.3 and when entered in the above equation, the
max allowable Pd(pk) = 390 mW for a max T
pulse shape for which the rise and fall times are insignificant
compared to the pulse width. If this is not the case in a
specific application, then the V
be multiplied together and the resulting power waveform
integrated to find the total dissipation across the device. This
then would be the number that has to be less than or equal to
For a repetitive pulse operating condition, time averaging
For pulse widths which are significant compared to the
Figure 12 of the MDC3105LT1 data sheet plots its
To use Figure 12 to determine the peak power rating for
Thus for a 20% duty cycle and a PW = 40 ms, Figure 12
Also note that these calculations assume a rectangular
Using TTR Designing for Pulsed Operation
Pd(pk) = (150 C − T
Pd(pk) = (T
Jmax
− T
Amax
Amax
O
)
and I
)
(556 C/W * r(t))
(R
O
qJA
waveforms should
* r(t))
A
= 85 C.
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MDC3105LT1
7
the Pd(pk) calculated above. A circuit simulator having a
waveform calculator may prove very useful for this purpose.
MDC3105LT1. Device instantaneous operation should
never be pushed beyond these limits. It shows the SOA for
the Transistor “ON” condition as well as the SOA for the
zener during the turn−off transient. The max current is
limited by the Izpk capability of the zener as well as the
transistor in addition to the max input current through the
resistor. It should not be exceeded at any temperature. The
BJT power dissipation limits are shown for various pulse
widths and duty cycles at an ambient temperature of 25 C.
The voltage limit is the max V
device. When the input to the device is switched off, the BJT
“ON” current is instantaneously dumped into the zener
diode where it begins its exponential decay. The zener clamp
voltage is a function of that BJT current level as can be seen
by the bowing of the V
currents. In addition to the zener’s current limit impacting
this device’s 500 mA max rating, the clamping diode also
has a peak energy limit as well. This energy limit was
measured using a rectangular pulse and then translated to an
exponential equivalent using the 2:1 relationship between
the L/R time constant of an exponential pulse and the pulse
width of a rectangular pulse having equal energy content.
These L/R time constant limits in ms appear along the V
versus I
lines intersect the V
given load should not exceed these limits at their respective
currents. Precise L/R limits on zener energy at intermediate
current levels can be obtained from Figure 11.
Figure 10 is the Safe Operating Area (SOA) for the
Notes on SOA and Time Constant Limitations
Z
curve for the various values of I
CC
limit. The L/R time constant for a
Z
versus I
CC
that can be applied to the
Z
curve at the higher
Z
at which the Pd
Z