Datasheet
FB
PGOOD
V
IN
LM21215A-1
V
OUT
AGND
COMP
PVIN
SW
EN
C
IN
C
OUT
L
F
R
C1
C
C1
C
C2
C
C3
R
FB1
R
FB2
R
C2
PGND
AVIN
C
F
11-16
3
4
17
19
18
20
8,9,10
5,6,7
R
F
SS/
TRK
C
SS
2
optional
HTSSOP-20
EN
GND
VIDA
1
10
WSON-10
3 mm x 3 mm
VIDB
VIDC
VIDS
9
8
7
4
VDD
IDAC_OUT
3
2
0 - 59.2 PA
LM10010
SYNC
1
CVDD
3V to 5.5V
C
VDD
C
BYPASS
VCNTL[3]
VCNTL[2]
VCNTL[1]
VCNTL[0]
TMS320C6670/
TMS320C6678
0.7V to 1.1V
DVDD18
R
PU1:4
LM10010
SNVS717C –JULY 2011–REVISED MARCH 2013
www.ti.com
APPLICATION INFORMATION
Design Example
In this example, an LM21215A-1 is used as the buck regulator to provide CVDD to the TMS320C6670 or
TMS320C6678 from 0.7V to 1.1V and an output current of up to 15A. The LM10010 in conjunction with VID
control from the DSP, provides control of the output voltage within this range with 6 bits of resolution. For this
example, the 400 mV of voltage range translates to a 6.4 mV resolution in the control of the regulator output
voltage. In this calculation, 1% resistor values are used. A schematic for this example is shown in the circuit of
Figure 15.
Figure 15. Typical Application Circuit
Setting the V
OUT
Range and LSB
Looking at the Typical Application Circuit in Figure 15, the following equation defines V
OUT
of a given regulator
(valid for V
OUT
> V
FB
):
(1)
Here, the output voltage is a function of the resistor divider from R
FB1
and R
FB2
. Additionally, there is a current
supplied by the LM10010 that helps drive the feedback resistor R
FB2
, thus lowering the necessary current
supplied through R
FB1
, and lowering V
OUT
.
10 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated
Product Folder Links: LM10010