datasheetbank_Logo   Integrated circuits, Transistor, Semiconductors Search and Datasheet PDF Download Site
Part Name :   

MC7906CD2T View Datasheet(PDF) - Motorola => Freescale

Part NameDescriptionManufacturer
MC7906CD2T THREE–TERMINAL NEGATIVE FIXED VOLTAGE REGULATORS Motorola
Motorola => Freescale Motorola
MC7906CD2T Datasheet PDF : 12 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
MC7900
APPLICATIONS INFORMATION
Design Considerations
The MC7900 Series of fixed voltage regulators are
designed with Thermal overload Protection that shuts down
the circuit when subjected to an excessive power overload
condition. Internal Short Circuit Protection that limits the
maximum current the circuit will pass, and Output Transistor
Safe–Area Compensation that reduces the output short
circuit current as the voltage across the pass transistor is
increased.
In many low current applications, compensation
capacitors are not required. However, it is recommended that
the regulator input be bypassed with a capacitor if the
regulator is connected to the power supply filter with long wire
lengths, or if the output load capacitance is large. An input
bypass capacitor should be selected to provide good
high–frequency characteristics to insure stable operation
under all load conditions. A 0.33 µF or larger tantalum, mylar,
or other capacitor having low internal impedance at high
frequencies should be chosen. The capacitor chosen should
have an equivalent series resistance of less than 0.7 . The
bypass capacitor should be mounted with the shortest
possible leads directly across the regulators input terminals.
Normally good construction techniques should be used to
minimize ground loops and lead resistance drops since the
regulator has no external sense lead. Bypassing the output is
also recommended.
Figure 7. Current Regulator
–20 V
Input
MC7905
10
IO = 200 mA
R
VO 10 V
+ 1.0 µF
Gnd
1.0 µF
+
Gnd
The MC7905, – 5.0 V regulator can be used as a constant current source when
connected as above. The output current is the sum of resistor R current and
quiescent bias current as follows.
5.0 V
IO = R + IB
The quiescent current for this regulator is typically 4.3 mA. The 5.0 V regulator was
chosen to minimize dissipation and to allow the output voltage to operate to within
6.0 V below the input voltage.
Figure 8. Current Boost Regulator
(– 5.0 V @ 4.0 A, with 5.0 A Current Limiting)
–10
0.56
InpuVt
0.56
0.56
2N3055*
or Equiv
– 5.0 V
Output
MJE200*
or Equiv
MC7905*
5.6
10 µF
Gnd +
1.0 µF
+
1.0 µF
+
Gnd
*Mounted on heatsink.
When a boost transistor is used, short circuit currents are equal to the sum of the
series pass and regulator limits, which are measured at 3.2 A and 1.8 A respectively
in this case. Series pass limiting is approximately equal to 0.6 V/RSC. Operation
beyond this point to the peak current capability of the MC7905C is possible if the
regulator is mounted on a heatsink; otherwise thermal shutdown will occur when
the additional load current is picked up by the regulator.
Figure 9. Operational Amplifier Supply
(±15 @ 1.0 A)
+20 V
Input
0.33 µF
Gnd
MC7815
+
1.0 µF
+
1.0 µF
+
1.0 µF
+
1.0 µF
+15 V
Output
1N4001
or Equiv
Gnd
– 20 V
Input
MC7915
–15 V
Output
The MC7815 and MC7915 positive and negative regulators may be connected as
shown to obtain a dual power supply for operational amplifiers. A clamp diode
should be used at the output of the MC7815 to prevent potential latch–up problems
whenever the output of the positive regulator (MC7815) is drawn below ground with
an output current greater than 200 mA.
MOTOROLA ANALOG IC DEVICE DATA
9
Direct download click here
 

Share Link : Motorola
All Rights Reserved © datasheetbank.com 2014 - 2019 [ Privacy Policy ] [ Request Datasheet ] [ Contact Us ]