PM6680ATR STMicroelectronics, PM6680ATR Datasheet - Page 34

• Manufacturer Part Number: PM6680ATR
• Description: IC CTRLR DUAL STEP DOWN 32VFQFPN
• Manufacturer: STMicroelectronics

Specifications of PM6680ATR

• Applications: Controller, Embedded Computer System
• Voltage - Input: 6 ~ 36 V
• Number Of Outputs: 2
• Voltage - Output: 0.9 ~ 5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN, 32-VFQFPN
• For Use With: 497-6379 - BOARD EVALUATION FOR PM6680A497-6378 - BOARD EVALUATION FOR PM6680497-6425 - BOARD EVAL BASED ON PM6680A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6896-2; PM6680ATR

Design guidelines
34/48
Equation 22
Choose a synchronous rectifier with low R
variation of the phase node voltage can bring up even the low side gate through its gate-
drain capacitance C
that minimizes the ratio C
Below there is a list of some possible low side MOSFETs.
Table 10. Low side MOSFET manufacturer
Dual n-channel MOSFETs can be used in applications with a maximum output current of
about 3 A. Below there is a list of some MOSFET manufacturers.
Table 14.
A rectifier across the low side MOSFET is recommended. The rectifier works as a voltage
clamp across the synchronous rectifier and reduces the negative inductor swing during the
dead time between turning the high-side MOSFET off and the synchronous rectifier on. It
can increase the efficiency of the switching section, since it reduces the low side switch
losses. A shottky diode is suitable for its low forward voltage drop (0.3 V). The diode reverse
voltage must be greater than the maximum input voltage V
reverse charge is preferable. Below there is a list of some shottky diode manufacturers.
Table 15.
Manufacturer
Manufacturer
Manufacturer
ST
ST
ST
Dual MOSFET manufacturer
Schottky diode manufacturer
RSS
STPS1L40M
STS4DNF60L
P
, causing cross-conduction problems. Choose a low side MOSFET
Series
conduction
RSS
Type
STS7NF60L
/C
Type
GS
=
(C
R
Forward voltage
DSon
GS
R
DSon
= C
×
0.5
(V)
DSon
⎛
⎜ ⎜
⎝
50
R
1
ISS
[VC11] 19
DSon
(mΩ)
−
. When high side MOSFET turns on, the fast
V
- C
V
IN
OUT
(mΩ)
max
RSS
Gate charge
⎞
⎟ ⎟
⎠
).
×
Rated reverse
I
voltage (V)
LOAD
(nC)
15
INmax
0.0625
C
--------------
C
40
RSS
(max)
GS
. A minimum recovery
2
Rated reverse voltage
Rated reverse voltage
Reverse current
(V)
(V)
60
60
(uA)
21
PM6680A