Datasheet

Analog Integrated Circuit Device Data
53 Freescale Semiconductor
MC34708
Functional Block Description
7.5.4.5 SW3
SW3 is fully integrated synchronous Buck PWM voltage mode control DC/DC regulator.
Figure 11. SW3 Block Diagram
The peak current is sensed internally for over-current protection purposes. If an over-current condition is detected the regulator
will limit the current through cycle by cycle operation and alert the system through the SW3FAULT SPI bit and issue an SCPI
interrupt via the INT pin.
SW3 can be programmed in step sizes of 25 mV as shown in Table 41.
Table 41. SW3 Output Voltage Programmability
Set Point SW3[4:0] SW3 Output (V) Set Point SW3[4:0] SW3 Output (V)
0 00000 0.6500 16 10000 1.0500
1 00001 0.6750 17 10001 1.0750
2 00010 0.7000 18 10010 1.1000
3 00011 0.7250 19 10011 1.1250
4 00100 0.7500 20 10100 1.1500
5 00101 0.7750 21 10101 1.1750
6 00110 0.8000 22 10110 1.2000
7 00111 0.8250 23 10111 1.2250
8 01000 0.8500 24 11000 1.2500
9 01001 0.8750 25 11001 1.2750
10 01010 0.9000 26 11010 1.3000
11 01011 0.9250 27 11011 1.3250
12 01100 0.9500 28 11100 1.3500
13 01101 0.9750 29 11101 1.3750
14 01110 1.0000 30 11110 1.4000
15 01111 1.0250 31 11111 1.4250
Driver
Controller
EA
Z1
Z2
Internal
Compensation
SW3IN
SW3LX
SW3FB
I
SEN SE
C
OSW3
C
IN SW 3
L
SW 3
SPI
Interface
GNDSW3
SW3
SW3MODE
SW3FAULT
V
REF
DAC
SPI
BP
D
SW 3