Linear Voltage Regulator Solution - Motorola M68060 User Manual

11.2.1.1.1 Linear Voltage Regulator Solution. This solution uses a linear voltage regula-
tor to supply 2 A at 3.3 V. This solution is inexpensive; however, conversion efficiency of only
up to 65% can be achieved. Figure 11-1 shows a solution using power BJTs. This solution
would be used primarily for applications that are cost sensitive, but not power sensitive. The
suggested linear solution meets the 3.3 V ± 5% MC68060 specifications.
5 V
C1
R1
D1
T1 = TIP32
T2 = 2N2222A
D1 = TL431CLP
D2,D3,D4 = IN4001
= 220 Ω
R1
R2,R3,R4 = 1K Ω
= 2.2K Ω
R5
= 47 µF
C1
= 0.01 µF
C2
= 0.033 µF
C3
= 47 µF
CL
11.2.1.1.2 Switching Regulator Solution. This solution uses switching regulators. Linear
Technologies offers two parts, the LTC1147 and LTC1148 and MAXIM offers the MAX767.
The main difference among these parts is a trade-off between price, part count, and conver-
sion efficiency.
The LTC1147 solution is less expensive and has one fewer MOSFET than the LTC1148
solution. The LTC1148 is less than $5 in 1000 piece quantities, and the LTC1147 is less
than $4 in 1000 piece quantities. In either of these solutions there are around 15 discrete
MOTOROLA
D2
T1
C2
Figure 11-1. Linear Voltage Regulator Solution
M68060 USER'S MANUAL
D3 D4
C3
T2
R4
Applications Information
3.3 V
CL
2 A
R2
R3
R5
11-7