![](/html/3c/3c61/3c612a873246437ee20726407fa8747adce866271244b56d7339ff0f495b60f9/bg1.png)
Demonstration board for the PM6680A dual synchronous
step-down controller with adjustable output voltages plus LDO
Features
■ Constant on-time control allows very fast load
transients
■ 6 V to 36 V input voltage range
■ 5 V auxiliary output voltage
■ Adjustable switching outputs
■ Lossless current sensing
■ Negative current limit
■ Soft-start internally fixed at 2.8 ms
■ Soft-end for output discharge
■ 200 kHz / 300 kHz, 300 kHz / 400 kHz, 400 kHz
/ 500 kHz (OUT1 / OUT2 selectable switching
frequency)
■ Selectable pulse skip and no-audible skip
modes at light loads
■ Independent power good signals
STEVAL-ISA053V2
Data Brief
STEVAL-ISA053V2
Description
The PM6680A is a dual step-down controller with
adjustable output voltages. This demonstration
board is designed to test the performance of the
PM6680A by employing a typical application
circuit which allows testing of all the PM6680A
device functions. The kit features two switching
sections, with (typically) 3.3 V and 1.8 V outputs,
from a 6 V to 36 V input voltage.
The typical operating switching frequency of the
two switching sections is 200 kHz / 300 kHz,
respectively. Each switching section delivers more
than 2.5 A of output current.
Moreover, an internal linear regulator can provide
5 V @ 100 mA peak current.
June 2008 Rev 1 1/4
For further information contact your local STMicroelectronics sales office.
www.st.com
4
![](/html/3c/3c61/3c612a873246437ee20726407fa8747adce866271244b56d7339ff0f495b60f9/bg2.png)
Circuit schematic STEVAL-ISA053V2
1 Circuit schematic
Figure 1. Schematic diagram
J10
OUT2+
OUT2+
J1
J1
1
J2J2-VIN
-VIN
J5J5+VIN
+VIN
VIN
2/4
LDO5V+
LDO5V+
J3
J3
R26
R26
V+
D1
D1
1
1
PGND
CIN
CIN
NM
NM
+
+
PGND
C2C215u
15u
PGND
C1C115u
15u
PGND
3R9
3R9
4u7
4u7
C26
C26
+
+
SGND
100n
100n
C19
C19
SGND
RLD5V
RLD5V
100K
100K
SGND
4u7
4u7
C21
C21
+
+
SGND
C20
1uF
C20
1uF
SGND
47R
47R
R9
R9
C22
C22
BOOT2
BOOT1
2
1
BAT54A/SOT
BAT54A/SOT
3
V+
15u
15u
C4
C4
15u
15u
C3
C3
VIN
S4
S4
JP2SO
JP2SO
1 2
C13
C13
R3
R3
8
7
6
51
BOOT2
10R
10R
U1
U1
VIN
5
10R
10R
C6
C6
51
6
7
8
R4
R4
C14
C14
NM
NM
NM
NM
C5
C5
LDO
VCC
100n
100n
NM
NM
NM
NM
OUT5V
M1
M1
MOSFET-N-SO8
MOSFET-N-SO8
4
100n
100n
9
BOOT2
BOOT1
23
R22
R22
4
M2
M2
MOSFET-N-SO8
MOSFET-N-SO8
S5
S5
JP2SO
JP2SO
2
L1L13V3
1
3
2
R20
R20
10
HGATE2
HGATE1
22
0R
0R
2
3
12
L2
L2
1 2
1
J4
J4
3V3
8
7
6
51
0R
0R
11
21
M4
M4
51
6
7
8
R5
R5
NM
NM
R11
R11
19
18
V+
31
220nF
220nF
SGND
R10
R10
BOOT1
PGND
PGND
R6
R6
NM
NM
S8S8JP3SO
JP3SO
3
1
560K
560K
R18
R18
M3
M3
MOSFET-N-SO8
MOSFET-N-SO8
4
1 0R
1 0R
R2
R2
13
PHASE2
PHASE1
15
R23
R23
4
MOSFET-N-SO8
MOSFET-N-SO8
5V
5V
S9
S9
3
1
OUT1+
OUT1+
2
C8
C8
NM
NM
+
+
C7
C7
NM
NM
+
+
C24
100n
C24
100n
D3
D3
SMA
SMA
12
3
2
R7 500R
R7 500R
12
LGATE2
LGATE1
20
R8
R8
0R
0R
2
3
R19
R19
560K
560K
12
D2
D2
SMA
SMA
C12
C12
330uF
330uF
+
+
C11
C11
330uF
330uF
+
+
C25
C25
JP3SO
JP3SO
C9
C9
CSENSE2
CSENSE1
100n
100n
2
J9
J9
1
100n
100n
PGND
14
PGND
V5SW
17
V5SW
500R
500R
100n
100n
C10
C10
J10
PGND
OUT2-
OUT2-
R25
R25
PGND
C15
C15
SGND
1
8
OUT2
SGND
COMP1
OUT1
29
30
OUT5V
1
J8
J8
PGND
1
PGND
R30
?
R30
?
?
?
R29
R29
SGND
LDO_ADJ
LDO_ADJ
NM
NM
SGND
A - S12 CLOSED
LIKE 4-PIN JUMPER
B - S14 CLOSED
FB1
28
FB1
PGOOD2
27
3 100K
3 100K
R1
R1
V+
C18
C18
100pF
100pF
1K
1K
+
+
C - S12.1 TO S14.2
12
3 JP2SO
3 JP2SO
S1
S1
7
LDO
SHDN
5
PGOOD1
PGOOD1
J7J7PGOOD2
J6
J6
NM
NM
VIN
R28
R28
?
?
1
R32
R32
?
?
R31
R31
?
?
SGND
R33
R33
?
?
SGND
4u7
4u7
C28
C28
SGND
C27
C27
1uF
1uF
SGND
FSE
L
3
SKI
P
24
VREF
32
EN1
25
EN2
4
PGOOD2
SGND
560K
560K
R17
R17
FB1
R27
R27
SGND
1
3
S1S1JP3SO
S1S1JP3SO
2
LDO_FB
PM6681_VFQFPN32
PM6681_VFQFPN32
R15
R15
100K
100K
V+V+V+
?
?
SGND
V+
JP4I
JP4I
S3
S3
4
31
2
JP4I
JP4I
S10
S10
4
31
2
SGND
100n
100n
CREF
CREF
4
5
3
6
2
7
1
8
S2
S2
R14
R14
100K
100K
R16
R16
100K
100K
C23
10pF
C23
10pF
SWDIP-4
SWDIP-4
SGND
SGND
SGND
J11
J11
EXT5V
EXT5V
V5SW
OUT5V
150pF
150pF
C17
C17
1
2 JP2SO
2 JP2SO
S1
S1
2
2
6
FB2
COMP2
LDO_FB
PGOOD1
26
16
LDO_FB
2 100K
2 100K
R1
R1
V+
C16
C16
R24
R24
PGND
OUT1-
OUT1-