AN50001

Reverse battery protection in automotive applications
Rev. 1.0 — 12 January 2021

application note

Document information
Information

Content

Keywords

automotive, reverse battery protection, RBP

Abstract

This application note gives details of four methods of reverse battery protection (RBP) that can beused in 12 V automotive systems.

AN50001

Nexperia

Reverse battery protection in automotive applications

1. Introduction
This aim of this application note is to help the reader gain an insight into how to protect 12 V
automotive systems from being exposed to a reversed biased battery condition e.g. during
maintenance where the battery leads may be reconnected in the opposite polarity.
Four methods of reverse battery protection (RBP) are discussed:••••

Recovery rectifier (PN diode)
Schottky rectifierP-channel MOSFET
N-channel MOSFETThe dominant losses in RBP applications are due to conduction. The ordering of the components inthe above list is important as it gives an indication of the least capable to most capable methods. In
other words for a particular current flow Recovery rectifiers exhibit the greatest loss and N-channel
MOSFETs the least loss. Table 1 summarises the key factors of each method.
Table 1. Reverse battery positive rail protection options
Recovery rectifier (PN diode) e.g. PNE20030EP
Recovery rectifier(PN diode)in CFP5
Vbat+• Low power, e.g. ~1 A supply• Lower costLoad
• Device rating: 200 V, 3 A• High conduction lossVbat-

aaa-032866

Schottky rectifier
Vbat+
Load
Vbataaa-032867

P-channel MOSFET
Vbat+
Load
Vbat-

P-channel MOSFET e.g. BUK6Y14-40P in
LFPAK56• Medium - high power, e.g. ~5.7 A supply• Device specification: 14 mΩ, 40 V, 110 W• High-side, cost competitive vs N-channel
with charge pumpaaa-032868

N-channel MOSFET
Vbat+
Chargepump

Schottky rectifier e.g. PMEG045T150EPD in
CFP15• Low power , e.g. ~3 A supply• Slightly higher cost
• Device rating: 45 V, 15 A
• High leakage current, especially at higher
temperatures

Load

Vbat-

N-channel MOSFET e.g. BUK7J1R4-40H in
LFPAK56E• High power, e.g. ~25 A supply• Device specification: 1.4 mΩ, 40 V, 395 W• High-side: charge pump / gate boost voltage
required• Low-side: very cost effective solution

aaa-032879

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

2 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications

2. Recovery rectifier (PN diode) steady state conduction loss
Using a Recovery rectifier as a blocking diode can be considered as the simplest and most costeffective way to realize a reverse battery protection (RBP) circuit. Inserting a Recovery rectifierin series with the load ensures that current can flow only when the battery is correctly connected.
There is no control input needed, resulting in a low complexity and low component count. The
usage of a Recovery rectifier for RBP is however compromised by the high forward voltage drop of
the PN junction. This is the reason why Recovery rectifiers are only used for low power applications(load currents below ~1 A).
Recovery rectifier(PN diode)
Vbat+
Load
Vbataaa-032866

Fig. 1.

Recovery rectifier RBP

Inrush current through the rectifier must be considered e.g. when the battery is switched into circuitand the bulk capacitance begins to charge. The peak current and duration of the pulse must be
checked to ensure it does not exceed specification.
The steady state conduction losses, Ploss, can be calculated by using the forward voltage drop VF
of the diode given for a steady state temperature of the PN junction and the load current Iload:

Ploss = I load ×VF (T)(1)

The forward voltage drop of a PN junction decreases by -1.9 mV/K as the device heats up,
lowering the losses at higher junction temperatures. Nevertheless the maximum total power
dissipation of the Recovery rectifier has to be respected as indicated in the data sheet of theparticular diode.
In the option examples above the PNE20030EP Recovery rectifier is identified as being well suited
to this type of application. Using close to the example current in a simulation gives an indication of
the expected forward voltage drop, junction and PCB temperatures, with the ambient temperature(on the product’s case) of 105 °C.

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

3 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications

Fig. 2.

Recovery rectifier RBP simulation schematic
See graphs of the simulation data results in Fig. 3, Fig. 4 and Fig. 5.

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

4 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications
aaa-033031

180
Tj = 167.2 °C

T

(°C)

160

140

Tmb = 115.7 °C

120

100

0

200

400

600

800

1000

1200
time (s)Fig. 3.

Recovery rectifier simulation results - junction and mounting base temperatures
aaa-033032

3

1
IL
(A)
0.8

VAK
(V)

2

aaa-033033

0.961

0.6

0.4
1

0.63 V

0.2

0

0
0.008

Fig. 4.

0.01

0.012

0.014
time (s)Recovery rectifier simulation results - D1
anode-to-cathode voltage

AN50001

application noteFig. 5.

0.008

0.01

0.012

0.014
time (s)Recovery rectifier simulation results - load
current

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

5 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications

3. Schottky rectifier steady state conduction loss
In order to overcome the high conduction losses of a Recovery rectifier, designers could use a
Schottky rectifier for RBP. A Schottky device as blocking diode comes with the same advantages
as a Recovery rectifier (least complexity). Thanks to its lower forward voltage drop it can be used
for higher load currents up to approximately 3 A. However a Schottky rectifier comes with a higher
leakage current due to its metal-semiconductor interface. The leakage current of a Schottky
rectifier becomes significantly larger at higher junction temperatures, resulting in unwanted effects
such as thermal runaway.
Schottky rectifier
Vbat+
Load
Vbataaa-032867

Fig. 6.

Schottky rectifier RBP

Similarly to the Recovery rectifier, inrush current through the diode must be considered e.g. when
the battery is switched into circuit and the bulk capacitance begins to charge. The peak current andduration of the pulse must be checked to ensure it does not exceed specifications.
Like in the case of the Recovery rectifier the conduction losses can be calculated by multiplying thetemperature-dependent voltage drop with the load current:
Also for Schottky rectifiers the junction temperature must not exceed the specified maximum
junction temperature which is 175 °C for automotive types.
In the option examples above the Schottky rectifier PMEG045T150EPD is identified as being
well suited to this type of application. Using close to the example current in simulation gives anindication of the expected forward voltage drop, power dissipation, junction and PCB temperatures
for an ambient temperature of 105 °C on the product’s case

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

6 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications

Fig. 7.

Schottky rectifier RBP simulation
See graphs of the simulation data results in Fig. 8, Fig. 9 and Fig. 10.

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

7 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications
aaa-033034

180
T

(°C)

160
Tj = 147.7 °C
140

Tmb = 116.3 °C

120

100

0

200

400

600

800

1000

1200
time (s)Fig. 8.

Schottky rectifier simulation results - junction and mounting base temperatures
aaa-033035

1

IL
(A)

VAK
(V)

0.8

1

0.251 V

0
0.008

0

Fig. 9.

2.51 A

2

0.4

0.008

aaa-033036

3

0.01

0.012

0.014
time (s)

0.01

0.012

0.014
time (s)Schottky rectifier simulation results - D1 anode- Fig. 10. Schottky rectifier simulation results - load
current
to-cathode voltage

4. P-channel MOSFET solution steady state conduction loss
In RBP applications the MOSFET can be considered as operating in two modes: “DIODE” modeand “MOSFET” mode.
During manufacture a parasitic PN junction diode is created within each MOSFET cell, the antiparallel “diode” on the die actually comprises many parallel diodes distributed uniformly across thewhole active die area.
P-channel MOSFET
Vbat+
Load
Vbat-

aaa-032868

Fig. 11. P-channel MOSFET RBP

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

8 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications
When the MOSFET is not enhanced i.e. the gate terminal does not have a sufficiently negative
voltage below its source to exceed its minimum threshold to turn-on then, with the battery
connected correctly, it behaves as a forward biased DIODE. The power loss in the device is the
product of the forward diode voltage and current flowing through it. The forward diode voltage
decreases with increase in temperature by -1.9 mV/K. Therefore as the die heats the power
dissipation reduces for a given current.
Once the gate-source threshold is reached the MOSFET becomes enhanced and switches from
“DIODE” to “MOSFET” mode. Current then flows in the drain-source channel. The power loss isthen the product of the on-state resistance RDSon and square of the current flowing in the channel.
To aid illustration a mix of data sheet calculation and simulation is used, the graphical results
obtained from simulation are shown in Fig. 12 below:

Fig. 12. P-channel MOSFET RBP simulation
The P-channel simulation is initially set up with a slightly higher load current to the Schottky rectifier
simulation.
To observe the device behaving as a diode look at the first portion of the junction temperatureplot where the junction rises significantly above case temperature. Later observe the differencein power dissipation when the MOSFET is enhanced and switches from “DIODE” to “MOSFET”
mode. If we consider a battery voltage of 13.5 V and VSD = 0.7 V typical at 25 °C, (values takenfrom the BUK6Y14-40P data sheet), driving a load resistance of 2.35 Ω. The expected power
dissipation would be somewhere around 0.7 V × (13.5 V/2.35 Ω) = 0 .7 V × 5.75 A = ~4.02 W. It
will be shown that the effects of temperature soon modify this expected result. This is true because
products within vehicles soon rise above this notional outside air ambient of 25 °C and the impact
on component behaviour must be considered.
Table 2. BUK6Y14-40P source-drain voltage characteristics
SymbolParameter
Conditions

Min

Typ

Max

Unit

-

-0.7

-1.2

V

Source-drain diodeVSD

source-drain voltage

IS = -64.4 A; VGS = 0 V; Tj = 25 °C

Temperatures above 125 °C are not uncommon dependent on product location within the vehicle
and the ambient air temperature. However the focus here is on a product operating with a casetemperature representing it being mounted on or near the engine jacket where the coolant
temperature is expected to be around 105 °C.

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

9 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications
Therefore what we see in the simulation is rather more accurate in that it accounts for the
impedance presented by the diode and the drop in diode forward voltage as the die temperaturerises. The load current is seen reduced to ~5.5 A and diode dissipation to ~3.07 W.
The mounting base temperature is that of the component’s location on the PCB. In other words
there will be some mounting base offset temperature expected dependent on how good the thermal
linkage is between the component’s mounting base (Tmb) and local pedestals connecting thecomponent to the product’s external case (local ambient) temperature of 105 °C.
The steady state condition considers the PCB thermal resistance Rth value dominant rather than
the transient Zth value. Simulation uses a Rth(PCB) of 30 K/W and reduced thermal capacitance toallow this dominance. If the device were left in DIODE mode the simulation shows the notionaltemperature on the PCB would be very close to the maximum junction temperature specification of
175 °C and damage to the PCB surface may result even though a high temperature material may
have been chosen for the application.
To illustrate the effect of DIODE mode self-heating the simulation delays enhancement to MOSFET
mode for ~35 s, see Fig. 13. In this time for a dissipation of 3.07 W, simulation shows Tmb has risen
to 168.13 °C and Tj to 172.2 °C.
180

aaa-033037

172.2

Tj
(°C)
160

140
126.47
120

100
180

168.13

Tmb
(°C)
160

140
125.51
120

100

0

200

400

600

800

1000

531

34.98

1200
time (s)Fig. 13. P-channel MOSFET RBP simulation results; Tj and Tmb
We can make a calculation based on using the data sheet Rth(j-mb) maximum value of 1.4 K/W, see
Table 3. For a power dissipation of 3.07 W we should expect the junction temperature to rise by
3.07 W × 1.4 K/W = 4.29 °C above Tmb. This calculation yields a junction temperature of 172.42 °C
which correlates reasonably well with the simulation.
Table 3. BUK6Y14-40P thermal characteristics
SymbolParameter
Conditions

Min

Typ

Max

Unit

Rth(j-mb)

-

1.1

1.4

K/W

AN50001

application notethermal resistance fromjunction to mounting
base

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

10 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications
When the device has sufficient gate bias applied to enhance (turn-on) the MOSFET element thedevice behaves as having a resistance in parallel with the diode. Table 4 gives the typical andmaximum values of the on-state resistance with a junction temperature of 25 °C.
Table 4. BUK6Y14-40P drain-source on-state resistance characteristics
SymbolParameter
Conditions

Min

Typ

Max

Unit

RDSon

-

11

14

mΩ

drain-source on-state
resistance

VGS = -10 V; ID = -10.8 A; Tj = 25 °C

Looking at the simulation results shown in Fig. 13, by 531 seconds after enhancement MOSFET
power dissipation and Tmb have dropped significantly to near steady state values of 683.77 mW
and 125.51 °C respectively. The load current has increased slightly to ~5.69 A indicating a
reduction in line impedance presented by the MOSFET to the battery.
If we make a power loss calculation based on 5.69 A load current and RDSon, the formula changes
2from DIODE power = V × I to MOSFET power = I R where I is drain current and R is RDSon, by
substitution (5.6942) × 14 mΩ = 453.9 mW. So why is there such a discrepancy with the 683.78
mW shown in the simulation? The above calculation was made using RDSon maximum @ 25°C
neglecting to factor in temperature.
RDSon has a positive temperature coefficient, see Fig. 14. The simulation models how RDSonchanges from that 14 mΩ maximum value at 25 °C to a 1.51 typical multiplier @ 125 °C.
Using 1.51 × 14 mΩ = 21.14 mΩ we can expect a power dissipation of (5.6942) × 21.14 mΩ =685.39 mW which correlates well with simulation.
Now if the power dissipation is multiplied by Rth(j-mb) we see a junction temperatureof 685.39 mW × 1.4 K/W = 0.956 °C above the mounting base temperature;
125.51 °C + 0.956 °C = 126.4695 °C which correlates very well with the junction temperature resultof 126.4705 °C seen in simulation.
aaa-030732

2.0aa = 1.51 @ 125 °C

1.5

1.0

0.5

0
-60

0

60

120

Tj (°C)180

Fig. 14. BUK6Y14-40P normalized drain-source on-state resistance as a function ofjunction temperature; typical values
The BUK6Y14-40P data sheet specifies the maximum permitted drain current at 25 °C and 100 °C,
see Table 5.
Table 5. BUK6Y14-40P limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134).
SymbolParameter

Conditions

Min

Max

Unit

ID

drain current

VGS = -10 V; Tmb = 25 °C

-

-64

A

VGS = -10 V; Tmb = 100 °C

-

-46

A

The maximum drain current derating for temperature is given by the equation below, where
maximum junction temperature Tj = 175 °C:

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

11 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications

Tj − Tmb
ID (Tmb ) = ID (25 °C) × −Tj − 25 °C(2)Hence the maximum permissible drain current = √[(175-125.51)/(175-25)] = 0.57 of full rated value@ 25°C. This gives a value of 64 A * 0.57 = 36.8 A, so we have excellent margin.
If the threshold voltage falls to -1 V the device is guaranteed to be off, see Fig. 15 and the DIODE
will be the only conduction path.
aaa-030729

-10-3
ID
(A)
min

-10-4

typ

max

-2

-3

-10-5

-10-6

0

-1

VGS (V)-4

VDS = -5 V; Tj = 25 °C
Fig. 15. BUK6Y14-40P sub-threshold drain current as a function of gate-source voltage
Hence losses when the device is in DIODE mode are large compared to when the device isoperating in MOSFET mode making the MOSFET ideally suited to larger current, high temperature
RBP applications.

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

12 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications

5. N-channel MOSFET solution steady state conduction loss
The majority of the description of P-channel behaviour also applies to N-channel devices. The
major difference being that to enhance an N-channel device into MOSFET mode its gate must be
biased positively with respect to its source.
N-channel MOSFET
Vbat+
Chargepump

Load

Vbataaa-032879

Fig. 16. N-channel MOSFET RBP
Importantly the N-channel MOSFET is capable of conducting larger currents as the RDSon value
for a particular die size is much lower than that of a P-channel device. The significantly lower
power dissipation in MOSFET mode means that the N-channel device is much better suited for
applications demanding larger currents.
The N-channel simulation uses as an example 24.5 A rather than 5.69 A of the P-channel
simulation. This is based on an ambient temperature of 105 ˚C and a near stable Tj of 140 ˚C. The
power dissipated in the MOSFET is around 1.165 W at 140 ˚C. The circuit board material used isassumed to be suitable for such high temperatures (“normal” FR4 is capable to around 105 ˚C only,
this is the ambient temperature here).
Referring to the simulation it can be seen that the source is at the battery positive voltage.
Therefore to bias the gate above battery positive voltage a charge pump is normally required. To
prevent the MOSFET being in linear mode where its RDSon would cause the device to dissipate
more power than desirable, gate switching must be delayed until a satisfactory threshold voltage
can be achieved.
In the simulation, there is a 30 second delay before the MOSFET switches on. During this time,
the full load current is passing through the MOSFET body diode and the junction temperaturereaches a peak of 175 ˚C, see Fig. 18. The power dissipated in the device is around 15 W. This
demonstrates that by switching on the MOSFET, a significant power saving can be achieved.

Fig. 17. N-channel MOSFET RBP simulation

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

13 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications
aaa-033038

180

175.11

Tj
(°C)
160

140

120

100
0

200

400

600

800

1000

1200
time (s)Fig. 18. N-channel MOSFET RBP simulation results; Tj

6. Summary
The four key methods of reverse battery protection have been discussed.
Guidance has been provided to clarify the best approach to meet demands of the application whileachieving optimal cost and performance.
Nexperia offers products which are very well suited for RBP applications.
Choose from very cost-effective Recovery rectifiers or Schottky rectifiers as solutions for lower
power applications. Choose from P-channel and N-channel MOSFETs as the load current
increases. Nexperia offers a range of thermally and electrically efficient device packages to support
each area of application. To assist in that selection process electro-thermal simulation results areincluded in this application note and those simulations are available for the reader to explore via
the Nexperia website interactive application note pages.

7. References
•
•
•
•
•

PNE20030EP data sheet
PMEG045T150EPD data sheet
BUK6Y14-40P data sheet
BUK7J1R4-40H data sheet
Nexperia interactive application notes

8. Revision history
Table 6. Revision history
Revision
Date
numberDescription

1.0

Initial version

2021-01-12

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

14 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications

9. Legal information
Definitions
Draft — The document is a draft version only. The content is still underinternal review and subject to formal approval, which may result in
modifications or additions. Nexperia does not give any representations or
warranties as to the accuracy or completeness of information included hereinand shall have no liability for the consequences of use of such information.

Disclaimers
Limited warranty and liability — Information in this document is believed
to be accurate and reliable. However, Nexperia does not give any
representations or warranties, expressed or implied, as to the accuracy
or completeness of such information and shall have no liability for theconsequences of use of such information. Nexperia takes no responsibility
for the content in this document if provided by an information source outsideof Nexperia.
In no event shall Nexperia be liable for any indirect, incidental, punitive,
special or consequential damages (including - without limitation - lost
profits, lost savings, business interruption, costs related to the removalor replacement of any products or rework charges) whether or not suchdamages are based on tort (including negligence), warranty, breach ofcontract or any other legal theory.
Notwithstanding any damages that customer might incur for any reason
whatsoever, Nexperia’s aggregate and cumulative liability towards customer
for the products described herein shall be limited in accordance with theTerms and conditions of commercial sale of Nexperia.
Right to make changes — Nexperia reserves the right to make changes
to information published in this document, including without limitation
specifications and product descriptions, at any time and without notice. This
document supersedes and replaces all information supplied prior to the
publication hereof.
Suitability for use — Nexperia products are not designed, authorized or
warranted to be suitable for use in life support, life-critical or safety-criticalsystems or equipment, nor in applications where failure or malfunctionof an Nexperia product can reasonably be expected to result in personal
injury, death or severe property or environmental damage. Nexperia and its
suppliers accept no liability for inclusion and/or use of Nexperia products insuch equipment or applications and therefore such inclusion and/or use is at
the customer’s own risk.
Applications — Applications that are described herein for any of theseproducts are for illustrative purposes only. Nexperia makes no representation
or warranty that such applications will be suitable for the specified use
without further testing or modification.
Customers are responsible for the design and operation of their applications
and products using Nexperia products, and Nexperia accepts no liability forany assistance with applications or customer product design. It is customer’ssole responsibility to determine whether the Nexperia product is suitableand fit for the customer’s applications and products planned, as well as
for the planned application and use of customer’s third party customer(s).
Customers should provide appropriate design and operating safeguards tominimize the risks associated with their applications and products.
Nexperia does not accept any liability related to any default, damage, costs
or problem which is based on any weakness or default in the customer’s
applications or products, or the application or use by customer’s third party
customer(s). Customer is responsible for doing all necessary testing for thecustomer’s applications and products using Nexperia products in order toavoid a default of the applications and the products or of the application or
use by customer’s third party customer(s). Nexperia does not accept any
liability in this respect.
Export control — This document as well as the item(s) described herein
may be subject to export control regulations. Export might require a priorauthorization from competent authorities.
Translations — A non-English (translated) version of a document is forreference only. The English version shall prevail in case of any discrepancy
between the translated and English versions.

Trademarks
Notice: All referenced brands, product names, service names andtrademarks are the property of their respective owners.

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

15 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications

List of Tables
Table 1. Reverse battery positive rail protection options...... 2
Table 2. BUK6Y14-40P source-drain voltage
characteristics.......................................................................9
Table 3. BUK6Y14-40P thermal characteristics................. 10
Table 4. BUK6Y14-40P drain-source on-state
resistance characteristics................................................... 11
Table 5. BUK6Y14-40P limiting values.............................. 11
Table 6. Revision history....................................................14

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

16 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications

List of Figures
Fig. 1. Recovery rectifier RBP............................................. 3
Fig. 2. Recovery rectifier RBP simulation schematic........... 4
Fig. 3. Recovery rectifier simulation results - junction
and mounting base temperatures........................................ 5
Fig. 4. Recovery rectifier simulation results - D1
anode-to-cathode voltage.................................................... 5
Fig. 5. Recovery rectifier simulation results - load current... 5
Fig. 6. Schottky rectifier RBP...............................................6
Fig. 7. Schottky rectifier RBP simulation..............................7
Fig. 8. Schottky rectifier simulation results - junction
and mounting base temperatures........................................ 8
Fig. 9. Schottky rectifier simulation results - D1 anodeto-cathode voltage................................................................8
Fig. 10. Schottky rectifier simulation results - load current... 8
Fig. 11. P-channel MOSFET RBP........................................8
Fig. 12. P-channel MOSFET RBP simulation...................... 9
Fig. 13. P-channel MOSFET RBP simulation results;
Tj and Tmb.........................................................................10
Fig. 14. BUK6Y14-40P normalized drain-source onstate resistance as a function of junction temperature;
typical values......................................................................11
Fig. 15. BUK6Y14-40P sub-threshold drain current as
a function of gate-source voltage.......................................12
Fig. 16. N-channel MOSFET RBP..................................... 13
Fig. 17. N-channel MOSFET RBP simulation.................... 13
Fig. 18. N-channel MOSFET RBP simulation results; Tj.... 14

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

17 / 18

AN50001

Nexperia

Reverse battery protection in automotive applications

Contents
1. Introduction................................................................... 2
2. Recovery rectifier (PN diode) steady state
conduction loss..................................................................3
3. Schottky rectifier steady state conduction loss.........6
4. P-channel MOSFET solution steady state
conduction loss..................................................................8
5. N-channel MOSFET solution steady state
conduction loss................................................................13
6. Summary..................................................................... 14
7. References.................................................................. 14
8. Revision history..........................................................14
9. Legal information........................................................15© Nexperia B.V. 2021. All rights reserved

For more information, please visit: http://www.nexperia.com
For sales office addresses, please send an email to: salesaddresses@nexperia.com
Date of release: 12 January 2021

AN50001

application note

All information provided in this document is subject to legal disclaimers.

Rev. 1.0 — 12 January 2021

© Nexperia B.V. 2021. All rights reserved

18 / 18