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NCP4371AACDR2G

P1-P3P4-P6P7-P9P10-P12P13-P14
NCP4371
www.onsemi.com
10
BC over
D−initial low
Continuous mode request
Short D+/D−
open D− pull−down
START
Power−On
Reset
Open D+/D−
D− pull−down
BC Done
HVDCP
Discrete
HVDCP
Continuous
5 V request
9 V request
12 V request
20 V request
5 V request
increment
request
decrement
request
unplug BC
done
Figure 17. NCP4371 State Diagram
V
BUS
= 5 V
V
BUS
= 5 V
V
BUS
= 20 V
unplug
V
BUS
= 12 VV
BUS
= 9 V
V
BUS
= V
BUS
− 200 mV
min. 3.6 V
V
BUS
= V
BUS
+ 200 mV
max. 12 V/20 V for class A/B
NCP4371
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11
Power Limit
The protocol decoder and the power limit logic will limit
maximum output current to keep regulation within
recommended V
out
/I
out
operating range. The Power Limit
block adjusts V
REFC
voltage reference at the current
regulation loop in order to limit the maximum output current.
The NCP4371 is designed to give a user a high degree of
freedom to optimize maximum power and current limit
profile of the target application. The user can scale both –
maximum output power and maximum current limit
independently.
The NCP4371 has two constant power curves defined –
“Option A” for Class A only and “Option B” for either Class
A or Class B. Power Option C shall be used for applications
where constant power regulation is not required. If Power
Option C is selected then power limiting curve is ignored.
The applications based on Power Option C operate in
“constant current regulation mode”.
In order to scale the power limit curve for the given power
a selection of the current sense resistor has to be done. The
relation between current sense resistor and output power
limit is given by the curves in Figure 18.
Figure 18. R
SENSE
vs. P
OUT
Limit Curve
P (W)
6
8
10
14
18
20
Rsense (mW)
242221 2519171615 18 20 23
POUT Limit Option A
12
16
POUT Limit Option B
The characteristics in the Figure 23 cover a range P
OUT
=
15 – 25 W. For powers outside this interval following
formula can be used for R
SENSE
selection:
O
ption A (Class A only) :
(eq. 1
)
R
SENSE
+
168
P
max
[mW]
O
ption B (Class A & B) :
(eq. 2
)
R
SENSE
+
277
P
max
[mW]
Once the Power limit is defined by an R_SENSE selection
the user needs to define a maximum output current limit.
This current limit can be given by a connector or cable
maximum current rating.
There are 5 current limit options available for Power
Option A and 8 current limit options for Power Option B and
C. Each power limit option corresponds to a particular
Current Control Reference Voltage (V
REFC
), which limits
the maximum output current for the selected R_SENSE
resistor. The user has to make a selection from current limit
characteristics shown in Figure 19. Each power limit curve
represents a unique device option (see Table Device
Options).
Figure 19. Current Limit Characteristics
P (W)
1.2
1.4
2.0
2.4
3.0
3.4
I
OUT(MAX)
(A)
242221 2519171615 18 20 23
A
1.6
1.8
2.2
2.6
2.8
3.2
4.0
B
C
D
E
Power Option A Current Limit Selection
P (W)
0.8
2.0
2.8
3.6
4.0
I
OUT(MAX)
(A)
242221 2519171615 18 20 23
A
1.2
1.6
2.4
3.2
4.4
B
C
D
E
Power Option B Current Limit Selection
F
G
H
3.6
3.8
NCP4371
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12
Table 5. CURRENT LIMIT OPTION REFERENCE VOLTAGE
Current Limit Option A B C D E F G H
V
REFC
[mV] 14 17 22 28 33 38 44 57
Soft Short−Circuit Protection
In case of a short−circuit at the USB cable end or the
portable device USB receptacle it is desired to limit the short
circuit current to prevent a portable device or cable from a
damage. The NCP4371 offers an extended region of output
current limiting down to V
BUS
= 2.2 V. If the V
BUS
falls
below V
CC(OFF)
then the HVDCP logic is disabled and D+/−
pins are shorted. No further commands from the portable
device are accepted. The only feature enabled is the output
current limiting at the moment. The device stays in the
current limiting mode until V
CC
rises back above V
CC(ON)
threshold. The device logic will resume its operation and
goes to a default BC1.2 compatible mode. A new negotiation
between the charger and portable device has to be carried out
in order to enable HVDCP compatibility mode.
Discharge
If voltage level lower than actual V
BUS
is requested by PD
the discharge circuitry discharges the output capacitors to
reach the new voltage level in a short time. As well, the
discharge circuitry is activated if cable unplug event is
detected. The NCP4371 features two discharge paths. By
default, the discharge is done via built−in regulated current
source at VCC pin. If the VCC pin discharge capability is not
sufficient an external discharge resistor R
DIS
has to be used.
The discharge resistor is wired from a positive pole of the
output capacitor to the DISCHARGE pin. The minimum
recommended value of the discharge resistor R
DIS
is 70 W
for Class A and 120 W for Class B. The DISCHARGE pin
has an internal protection for a case the user wires the pin
directly to V
BUS
. If this condition is detected the discharge
MOSFET at the pin is turned off. It is highly recommended
to use an external discharge resistor always if Class B device
is used. In case of Class A device and C
OUT
< 1500 mF the
DISCHARGE pin can be left disconnected.
Dual Discharge Path
The NCP4371 allows to select between a single discharge
path and the dual discharge. By default, if an external
discharge resistor R
DIS
is connected between a positive pole
of the output capacitor and the DISCHARGE pin, the
NCP4371 recognize it and the internal discharge path via
VCC pin is disabled. Some applications may require even
stronger discharge capability or may need to discharge two
capacitors connected at two different nodes (USB−Type C
output capacitors before and after VBUS switch). The
NCP4371 allows to enable a simultaneous function of
internal discharge via VCC pin and external DISCHARGE
pin. Figure 20 shows an application idea of the dual
discharge paths in the USB−Type C adapter design.
C
out
C
bus
C
out
Discharge Path C
bus
Discharge Path
Figure 20. Dual Discharge Path − Application Idea (USB−Type C Adapter)
P1-P3P4-P6P7-P9P10-P12P13-P14

NCP4371AACDR2G

Mfr. #:
Buy NCP4371AACDR2G
Manufacturer:
ON Semiconductor
Description:
Battery Management USB HVDCP CONTROLLER
Lifecycle:
New from this manufacturer.
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