PTB78560A_15 Datasheet, PDF (14/27 Pages) Texas Instruments – 30-W, 24-V/48-V INPUT DC/DC CONVERTERS WITH AUTO-TRACK™ SEQUENCING

PTB78560A, PTB78560B
PTB78560C
SLTS249 – JUNE 2005
www.ti.com
Table 1. Standard Values of R_SET for Common Output Voltages
PTB78560A
PTB78560B
PTB78560C
V_O (Required)
1.8 V
R_SET
–
V_O (Actual)
–
R_SET
Open
V_O (Actual)
1.802 V
R_SET
–
V_O (Actual)
–
2V
–
–
200 kΩ
2.004 V
–
–
2.5 V
–
–
40.2 kΩ
2.498 V
–
–
3.3 V
–
–
5.36 kΩ
3.300 V
–
–
3.6 V
Open
3.611 V
309 Ω
3.600 V
–
–
5V
14.3 kΩ
5.005 V
–
–
–
–
9V
–
–
–
–
Open
9.015 V
10 V
–
–
–
–
73.2 kΩ
9.993 V
12 V
–
–
–
–
9.09 kΩ
12 V
13.2 V
–
–
–
–
0Ω
13.23 V
For other output voltages, the value of the required adjust resistor may be calculated using Equation 1.
R_SET + R_O
V_O
V_R
* V_MIN
*
R_P
(1)
Table 2 gives the output voltage adjust range and the required equation constants for the converter model
selected. To calculate the required value of R_SET, simply locate the applicable constants and substitute these
into the formula along with the desired output voltage.
Model #
V_R
R_O
R_P
V_MIN
V_MAX
Table 2. Adjust Ranges and Equation Constants
PTB78560A
1.24 V
49.91 kΩ
30.1 kΩ
3.61 V
5.5 V
PTB78560B
1.24 V
36.55 kΩ
24.9 kΩ
1.8 V
3.6 V
PTB78560C
2.5 V
37.27 kΩ
22.1 kΩ
9.02 V
13.2 V
Track ⁵
PTB78560A
+V_I
1 +V_I
+Sense ⁹
C_I
100 µF
2 _PEN
3 NEN
V_O Bus ¹⁰
V_O Adjust ⁸
6
V_O COM
4 −V_I
7
−Sense
−V_I
R_SET
C_O
220 µF
Figure 22. Output Voltage Adjustment
14
Submit Documentation Feedback