ISPPAC-POWR1208-01T44E Lattice, ISPPAC-POWR1208-01T44E Datasheet - Page 18

• Manufacturer Part Number: ISPPAC-POWR1208-01T44E
• Description: Supervisory Circuits PROGRAMMABLE PWR SUPPLY CONTR
• Manufacturer: Lattice

Specifications of ISPPAC-POWR1208-01T44E

• Number Of Voltages Monitored: 12
• Monitored Voltage: Adjustable
• Undervoltage Threshold: 1.03 V
• Overvoltage Threshold: 5.72 V
• Manual Reset: Not Resettable
• Watchdog: No Watchdog
• Supply Voltage - Max: 5.5 V
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Package / Case: TQFP-100
• Minimum Operating Temperature: - 40 C
• Factory Pack Quantity: 800
• Supply Current (typ): 15000 uA
• Supply Voltage - Min: 2.25 V

Lattice Semiconductor
Figure 8. MOSFET Gate Charge vs. Gate-Source Voltage
Using this method, it becomes straightforward to estimate the gate rise time for a given charging current. As an
example a MOSFET’s source voltage (V
(V
and down the plot of Figure 8, a V
to the product of current (I) and time (t
as:
For this example, let us assume a charging current of 10.9µA. Gate charging time is given by:
Validation of this result can be seen in the scope plot shown in Figure 9. The top set of traces shows gate rise times
for various (5.5µA to 50.3µA) gate drive currents. The trace labeled 10.9µA shows a 0-10V rise time of just over 3
milliseconds, which agrees to within 25% of our predicted value, well within the limits of device-to-device variation.
G
) will be 10V in this condition. The device’s gate-to-source voltage (V
GS
of 6.7V corresponds to ~40 nC of gate charge (Q
t
CHARGE-TIME
CHARGE-TIME
0
9
6
3
S
0
) will be 3.3V when the device is fully switched on, while the gate voltage
t
Q
CHARGE-TIME
G
, Total Gate Charge (nC)
) when current is constant, gate charging time can be expressed
20
=
i
=
10.9 x 10
18
40 x 10
dQ
dt
40
=
-9
Q
-6
I
C
G
A
= 3.7 x 1
60
GS
ispPAC-POWR1208 Data Sheet
) will therefore be 6.7V. Reading across
G
). Because charge is equal
(1)
(2)
(3)