Datasheet 1 Rev. 1.1
www.infineon.com/HITFET 2018-01-29
BTS3256D
Smart Low Side Power Switch
1 Overview
Features
• Slew rate control by dedicated pin enabling EMC optimized switching or
PWM operation
• Max. switching Frequency 12 kHz
• Clear detection of digital fault signal also during fast PWM operation due
to restart delay time
• Thermal and overload protection with time controlled auto restart behavior
• Time and Power limited active current limitation
• Minimum RDS(on) achieved with 3.3 V or 5 V logic input
• Electrostatic discharge protection (ESD)
• Very low leakage current
• Green Product (RoHS compliant)
• Digital Diagnostic Features
–Over temperature
–Over load
–Short circuit
– Clear detection due to a restart delay time
• Protection Functions
– Enhanced short circuit protection with time and power limited active current limitation
– Under voltage lock out
– Over temperature with time and temperature controlled auto restart
– Over load with power and time controlled auto restart
– ESD protection
Potential Applications
• All types of resistive, inductive and capacitive loads
• Suitable for loads with inrush current, such as motors, coils, solenoids or lamps
• Suitable for EMC optimized switching in slow operation mode
• Suitable for higher speed PWM controlled loads in fast operation mode
• Replacement of electromechanical relays, fuses and discrete circuits
• Micro controller compatible low side power switch with digital feedback for 12 V loads
Datasheet 2 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Overview
Description
The BTS3256D is a single channel low-side power switch in PG-TO-252-5-11 package providing embedded
protective functions. This HITFET™ is designed for automotive and industrial applications with outstanding
protection and control features.The power transistor is a N-channel vertical power MOSFET. The device is
controlled by a chip in Smart Power Technology.
The BTS3256D is an autorestart single channel low-side power switch in PG-TO-252-5-11 package providing
embedded protective functions. The device is able to switch all kind of resistive, inductive and capacitive
loads.
The ESD protection of the VS and IN/Fault pin is referenced to GND.
The BTS3256D is supplied by the VS Pin. This Pin should be connected to a reverse protected battery line. The
supply voltage is monitored by the under voltage lock out circuit. The Gate driving unit allows the device to
operate in the lowest ohmic range independent of the input signal level, 3.3 V or 5 V . For slow PWM application
the device offers smooth turn-on and off due to the embedded edge shaping function, to reduce EMC noise.
Furthermore the SRP pin can be used to customize the slew rate of the device in a wide range.
The Device is designed for driving automotive loads like motors,valves, coils or bulbs in continous or PWM
mode.
The over voltage protection is for protection during load-dump or inductive turn off conditions. The power
MOSFET is limiting the Drain-Source voltage to a specified level. This function is available even without any
supply.
The over temperature protection prevents the device from overheating due to overload and/or bad cooling
conditions. In order to reduce the device stress the edge shaping is disabled during thermal shutdown. After
thermal shutdown the device stays off for the specified restart delay time to enable a clear feedback readout
on the microcontroller. After this time the device follows the IN signal state.
At high dynamic overload conditions, such as short circuit, the device will either turn off immediately due to
the implemented over power limitation, or limit the current for a specified time and then switch off for the
restart delay time. Shutdown of the device is triggered if the power dissipation during limitation is above the
over power threshold. The short circuit shutdown is a timed restart function. The device will stay off for the
specified time and afterwards follow the IN signal state. In order to reduce the device stress the edge shaping
is disabled during protective turn off.
Table 1 Basic Electrical Data
Operating voltage VSOP 5.5 V.... 30 V
Over voltage protection VD(AZ) 40 V
Maximum ON State resistance at Tj = 150°C RDS(ON,max) 20 mΩ
Typical ON State resistance at Tj = 25°C RDS(ON,typ) 10 mΩ
Nominal load current ID(nom) 7.5 A
Minimum current limitation ID(lim) 42 A
Type Package Marking
BTS3256D PG-TO-252-5-11 BTS3256D
Datasheet 3 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 BTS3256D Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Voltage and current naming definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1 Pin Assignment BTS3256D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2 Pin Definitions and Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 General Product Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.2 Functional Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.3 Thermal Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5 Supply and Input Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1 Supply Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1.1 Under Voltage Lock Out / Power On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.2 Input Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.3 Electrical Characteristics - Supply and Input Stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6 Power Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6.1 Output On-state Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6.2 Output Timings and Slopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.3 Inductive Output Clamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.4 Electrical Characteristics - Power Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7 Control and Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.1 Readout of Fault Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.2 Adjustable Slew Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.3 Electrical Characteristics - Diagnostic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8 Protection Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.1 Thermal Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.2 Over Voltage Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.3 Short Circuit Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.4 Electrical Characteristics - Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
9 Application Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
9.1 Dimensioning of serial Resistor at IN pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
9.2 Further Application Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
10 Package Outlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
11 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table of Contents
Datasheet 4 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
BTS3256D Block Diagram
2 BTS3256D Block Diagram
Figure 1 Block Diagram for the BTS3256D
2.1 Voltage and current naming definition
Following figure shows all the terms used in this Datasheet, with associated convention for positive values.
Figure 2 Terms
Drain
GND
Gate
Driving
Unit
Over-
voltage
Protection
ESD
protection
IN / Fault
Over-
temperature
Protection
Overload
Protection
SRP
V
S
Short
circuit
Protection
BlockDiagram.emf
ϑ
Under
voltage
lockout
Slew rate
control
Terms.emf
VIN
VD
GND
I GND
Drain
Vbb
RL
IN / Fault
VS
VSID
IIN
IS
Vbb
GND
SRP
VSR P
Datasheet 5 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Pin Configuration
3 Pin Configuration
3.1 Pin Assignment BTS3256D
Figure 3 Pin Configuration
3.2 Pin Definitions and Functions
Pin Symbol Function
1VSSupply Voltage;
Connected to Battery Voltage with Reverse protection Diode and Filter against
EMC
2IN Control Input and Status Feedback; Digital input 3.3 V or 5 V logic.
3, Tab Drain Drain output;
Protected low side power output channel, usually connected via load to battery
4SRP Slew Rate Preset; Used to define slew rate, see Chapter 7.2 for details
5GND Ground; Power ground, pin connection needs to carry the load current from
Drain
Drain Drain
(top view )
GND
5
6 (Tab)
4
3
2
1
SRP
IN
V
S
PinConfiguration.emf
Datasheet 6 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
General Product Characteristics
4 General Product Characteristics
4.1 Absolute Maximum Ratings
Note: Stresses above the ones listed here may cause permanent damage to the device. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
1. Integrated protection functions are designed to prevent IC destruction under fault conditions described in the
data sheet. Fault conditions are considered as “outside” normal operating range. Protection functions are
not designed for continuous repetitive operation.
Table 2 Absolute Maximum Ratings1)
Tj = -40°C to150°C
All voltages with respect to ground, positive current flowing into pin (unless otherwise specified)
1) Not subject to production test, specified by design.
Parameter Symbol Values Unit Note or
Test Condition
Number
Min. Typ. Max.
Voltages
Supply voltage VS-0.3 – 30 V – P_4.1.1
Supply voltage during active clamping VS(pulse) -0.3 – 452)
2) Not for DC operation, only for short pulse (i.e. loaddump) for a total of 100 h in full device life.
V– P_4.1.2
Drain voltage VD-0.3 – 403)
3) Active clamped.
V– P_4.1.3
Drain voltage for short circuit
protection
VD(SC) 0–30V4)
4) The Device can not be switched on if VD > VD(SC)
P_4.1.4
Logic input voltage VIN -0.3 – 5.5 V – P_4.1.5
Slew Rate Preset maximum voltages VSRP -0.3 – 5.5 V 5)
5) SRP Pin is driven by an internal current source, so active driving from outside is not required,it may affect lifetime
and could cause parameter shifts outside the range given in datasheet
P_4.1.6
Energies
Unclamped single pulse inductive
energy
EAS 0–0.3J6)
ID = 22 A;
Vbb = 30 V
6) Refer to Figure 13 for maximum allowed inductance values
P_4.1.7
Temperatures
Junction Temperature Tj-40 – 150 °C – P_4.1.9
Storage Temperature Tstg -55 – 150 °C – P_4.1.10
ESD Susceptibility
ESD Resistivity
on input pins (IN,SRP,VS)
on Drain and GND pins
VESD
IN
OUT
–
-4
-8
–
–
–
–
4
8
kV
kV
kV
HBM7)
7) ESD susceptibility, HBM according to EIA/JESD 22-A114B, section4
P_4.1.11
Datasheet 7 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
General Product Characteristics
4.2 Functional Range
Note: Within the functional range the IC operates as described in the circuit description. The electrical
characteristics are specified within the conditions given in the related electrical characteristics
table.
4.3 Thermal Resistance
Table 3 Functional Range
Parameter Symbol Values Unit Note or Test Condition Number
Min. Typ. Max.
Supply Voltage VS5.5 – 30 V 1)
1) Refer to Figure 19 for Short Circuit test setup
P_4.2.1
Supply current in on IS––3 mA– P_4.2.2
Table 4 Thermal Resistance
Parameter Symbol Values Unit Note or Test Condition Number
Min. Typ. Max.
Junction to Case1)
1) Not subject to production test, specified by design
RthjC –0.91.1K/W– P_4.3.1
Junction to ambient1) RthjA –
–
80
45
–
–
K/W
K/W
@min. footprint
@ 6 cm2 cooling area, see
Figure 4
P_4.3.2
Datasheet 8 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
General Product Characteristics
Figure 4 Typical transient thermal impedance
ZthJA = f(tp) , Pulse D = tp/T, Ta = 25 °C
Device on 50mm×50mm×1.5mm epoxy PCB FR4 with 6cm
2 (one layer, 70 µm thick)
copper area for drain connection. PCB mounted vertical without blown air.
ZthJA
s
0.1
1
10
K/W
tp
Zth.emf
0.2
0.1
0.5
Single pulse
0.01
0.02
0.05
100
10-3 10-2 10-1
10-6 10-5 10-4 11010
2103
Datasheet 9 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Supply and Input Stage
5 Supply and Input Stage
5.1 Supply Circuit
The Supply pin VS is protected against ESD pulses as shown in Figure 5.
Due to an internal voltage regulator the device can be supplied from a reverse polarity protected battery line.
Figure 5 Supply Circuit
5.1.1 Under Voltage Lock Out / Power On Reset
In order to ensure a stable device behavior under all allowed conditions the Supply voltage VS is monitored by
the under voltage lock out circuit. All device functions are only given for supply voltages above under voltage
lockout. There is no failure feedback for VS<VSUVON.
Figure 6 Under Voltage Lock Out
5.2 Input Circuit
Figure 7 shows the input circuit of the BTS3256D. It’s ensured that the device switches off in case of open input
pin. A Zener structure protects the input circuit against ESD pulses. As the BTS3256D has a supply pin, the
operation of the power MOS can be maintained regardless of the voltage on the IN pin, therefore a digital
status feedback down to logic low is realized. For readout of the fault information, please refer to Diagnosis
“Readout of Fault Information” on Page 18.
Supply .emf
5.5V .. 30V
GND
VS
ZD
Regulator
BTS3256 D
V
SUVON
V
SUVOFF
functional
off
Device
UVLO.emf
Datasheet 10 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Supply and Input Stage
Figure 7 Input Circuit
5.3 Electrical Characteristics - Supply and Input Stages
Table 5 Electrical Characteristics - Supply and Input Stages
VS = 5.5 V to 30 V, Tj = -40°C to150°C
All voltages with respect to ground, positive current flowing into pin (unless otherwise specified)
Parameter Symbol Values Unit Note or Test Condition Number
Min. Typ. Max.
Under Voltage Lockout
UV-switch-on voltage VSUVON ––5.6V– P_5.3.1
UV-switch-off voltage VSUVOFF 4.0 – 5.5 V – P_5.3.2
UV-switch-off hysteresis VSUVHY –0.2– VVSUVON - VSUVOFF P_5.3.3
Digital Input / Fault Feedback
Low level voltage VINL -0.3 – 0.8 V – P_5.3.4
High level voltage VINH 2.0 – 5.5 V – P_5.3.5
Input pull down current IIN 20 50 100 µA VIN = 5.3 V;
no fault condition
P_5.3.6
Input pull down current in Fault IIN-Fault 123 mAVIN = 5.3 V; all fault
conditions
P_5.3.7
input.emfGND
IN/Fault
1.0mA
:
3.0mA
20µA
:
100µA
Datasheet 11 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Power Stage
6 Power Stage
The power stage is built by a N-channel vertical power MOSFET (DMOS).
6.1 Output On-state Resistance
The on-state resistance depends on the junction temperature TJ. Figure 8 shows this dependence for the
typical on-state resistance RDS(on).
Figure 8 Typical On-State Resistance RDSon = f(TJ), VS = 10 V, VIN = high
Figure 9 Typical On-State Resistance RDSon = f(VS), VIN=HIGH, Tambient=25°C
6
11
16
21
26
31
0102030
R
DS(on)
[ mΩ ]
V
S
[ V ]
rdson_Vs.emf
typ.
Datasheet 12 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Power Stage
6.2 Output Timings and Slopes
A high signal on the input pin causes the power MOSFET to switch on with a dedicated slope which is
optimized for low EMC emission. Figure 10 shows the timing definition.
Figure 10 Definition of Power Output Timing for Resistive Load
In order to minimize the emission during switching, the BTS3256D limits the slopes during turn on and off at
slow slew rate settings. For best performance of the edge shaping, the supply pin VS should be connected to
battery voltage. For supply voltages other than nominal battery, the edge shaping can differ from the Values
in the electrical characteristics table below.
6.3 Inductive Output Clamp
When switching off inductive loads with low-side switches, the Drain Source voltage VD rises above battery
potential, because the inductance intends to continue driving the current.
The BTS3256D is equipped with a voltage clamp mechanism that keeps the Drain-Source voltage VD at a
certain level. See Figure 11 for more details.
Figure 11 Output Clamp
IN
Low
High
ton toff t
VD
Vbb
OutputTiming.emt
tond
10 %
90 %
toffd
|dv/dt| s haping
|dv/ dt| s hapi ng
|dv/dt|on |dv/dt|off
80 %
20 % |dv/dt| shaping
output_clamp_curcuit.emf
GND
Drain
Datasheet 13 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Power Stage
Figure 12 Switching off an inductive Load
While demagnetization of inductive loads, energy has to be dissipated in the BTS3256D. This energy can be
calculated with following equation:
(6.1)
Following equation simplifies under assumption of RL = 0
(6.2)
Figure 13 shows the inductance / current combination the BTS3256D can handle.
For maximum single avalanche energy please also refer to EAS value in “Energies” on Page 6.
IN
Low
High
t
t
Von
V
bb
t
I
D
V
DAZ
Over temper ature or
shor t cir cuit detected
inductive_output_clamp.emf
EV
D(AZ)
Vbb V–D(AZ)
RL
-------------------------------- ln⋅1
RLIL
⋅
Vbb V–DAZ()
---------------------------------
–
⎝⎠
⎜⎟
⎛⎞
IL
+
L
RL
------
⋅⋅=
E1
2
---LIL
21
Vbb
Vbb V–D(AZ)
--------------------------------
–
⎝⎠
⎜⎟
⎛⎞
⋅=
Datasheet 14 Rev. 1.1
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Smart Low Side Power Switch
BTS3256D
Power Stage
Figure 13 Maximum allowed inductance values for single switch off (EAS) L=f (IL), Tj,start= 150 °C,
Vbb=30V, RL= 0 Ω
0,01
0,10
1,00
10,00
10
ID[ A ]
L [ mH ]
Max.
50
EAS .emf
Datasheet 15 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Power Stage
6.4 Electrical Characteristics - Power Stage
Table 6 Electrical Characteristics - Power Stage
VS = 5.5 V to 30 V, Tj = -40°C to150°C
All voltages with respect to ground, positive current flowing into pin (unless otherwise specified)
Parameter Symbol Values Unit Note or
Test Condition
Number
Min. Typ. Max.
Power Supply
On-state resistance RDS(on) –10– mΩTJ = 25°C;
ID = 20 A;
VIN = high
VS = 10 V
P_6.4.1
–1620 mΩTJ = 150°C;
ID = 20 A;
VIN = high
VS = 10 V
Nominal load current1) ID(nom) 7.5 8.7 – A TJ < 150°C;
TA 85°C SMD2);
VIN = high;
VS ≥ 10 V;
VDS = 0.5 V
P_6.4.2
ISO load current ID(ISO) 31 33 – A TJ < 150°C;
TC = 85°C;
VIN = high;
VS ≥ 10 V;
VDS = 0.5 V
P_6.4.3
Off state drain current IDSS –6 12 µAVD = 32 V;
VIN = low
P_6.4.4
–1 2 µA
1) TJ = 85°C;
VD = 13.5 V;
VIN = low
P_6.4.5
Standby supply current ISSS –3 8 µATJ = 85°C;
VD = 13.5 V;
VIN = low
P_6.4.6
Dynamic Characteristics
power up settling time tinit –1025 µsVS > 6V
first rising edge on
IN pin.
P_6.4.7
Timings with fastest slew rate setting
Turn-on delay tond_fast –4 10 µsRL = 2.2 Ω;
RSRP = OPEN;
Vbb = VS = 13.5 V;
see Figure 10
P_6.4.8
Datasheet 16 Rev. 1.1
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Smart Low Side Power Switch
BTS3256D
Power Stage
Turn-on time ton_fast –1122 µsRL = 2.2 Ω;
RSRP = OPEN;
Vbb = VS = 13.5 V;
see Figure 10
P_6.4.9–
Turn-off delay toffd_fast 41015 µsRL = 2.2 Ω;
RSRP = OPEN;
Vbb = VS = 13.5 V;
see Figure 10
P_6.4.10–
Turn-off time toff_fast 91624 µsRL = 2.2 Ω;
RSRP = OPEN;
Vbb = VS = 13.5 V;
see Figure 10
P_6.4.11–
Slew rate on -dVD/dton_fast 1.2 2.2 3.8 V/µs RL = 2.2 Ω;
RSRP = OPEN;
Vbb = VS = 13.5 V;
see Figure 10
P_6.4.12–
Slew rate off dVD/dtoff_fast 1.2 2.2 3.8 V/µs RL = 2.2 Ω;
RSRP = OPEN;
Vbb = VS = 13.5 V;
see Figure 10
P_6.4.13–
Slew rate during edge shaping |dV/dt|shaping_fast –0.66– V/µsRL = 2.2 Ω;
RSRP = OPEN;
Vbb = VS = 13.5 V;
see Figure 10
P_6.4.14–
Timings with slowest slew rate setting
Turn-on delay tond_slow –2260 µsRL = 2.2 Ω;
RSRP = GND;
Vbb = VS = 13.5 V;
see Figure 10
P_6.4.15–
Turn-on time ton_slow – 85 200 µs RL = 2.2 Ω;
RSRP = GND;
Vbb = VS = 13.5 V;
see Figure 10
P_6.4.16–
Turn-off delay toffd_slow – 75 110 µs RL = 2.2 Ω;
RSRP = GND;
Vbb = VS = 13.5 V;
see Figure 10
P_6.4.17–
Turn-off time toff_slow 40 150 220 µs RL = 2.2 Ω;
RSRP = GND;
Vbb = VS = 13.5 V;
see Figure 10
P_6.4.18–
Table 6 Electrical Characteristics - Power Stage (cont’d)
VS = 5.5 V to 30 V, Tj = -40°C to150°C
All voltages with respect to ground, positive current flowing into pin (unless otherwise specified)
Parameter Symbol Values Unit Note or
Test Condition
Number
Min. Typ. Max.
Datasheet 17 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Power Stage
Slew rate on -dVD/dton_slow 0.08 0.2 0.6 V/µs RL = 2.2 Ω;
RSRP = GND;
Vbb = VS = 13.5 V;
see Figure 10
P_6.4.19
Slew rate off dVD/dtoff_slow 0.08 0.2 0.6 V/µs RL = 2.2 Ω;
RSRP = GND;
Vbb = VS = 13.5 V;
see Figure 10
P_6.4.20
Slew rate during edge shaping |dV/dt|shaping_slow – 0.088 – V/µs RL = 2.2 Ω;
RSRP = GND;
Vbb = VS = 13.5 V;
see Figure 10
P_6.4.21
Inverse Diode
Inverse Diode forward voltage VD-0.3 -1.0 -1.5 V ID = -12 A;
VS = 0 V;
VIN = 0.0 V
P_6.4.22
1) Not subject to production test, specified by Design.
2) Device mounted according to EIA/JESD 52_2, FR4, 50×50×1.5 mm; 35µm Cu, 5µm Sn; 6cm
2.
PCB mounted without blown air
Table 6 Electrical Characteristics - Power Stage (cont’d)
VS = 5.5 V to 30 V, Tj = -40°C to150°C
All voltages with respect to ground, positive current flowing into pin (unless otherwise specified)
Parameter Symbol Values Unit Note or
Test Condition
Number
Min. Typ. Max.
Datasheet 18 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Control and Diagnosis
7 Control and Diagnosis
The BTS3256D provides digital fault feedback on the IN pin without the need of an ADC.
Additonally the device features an adjustable slew rate via the SRP pin.
7.1 Readout of Fault Information
The BTS3256D provides digital status information via an increased current on the IN / Fault pin.
The voltage on this pin is pulled down to logic low when a fitting serial resistor is used. An example for the
required circuitry is shown in Figure 14. The increased current IIN(fault) is one order of magnitude above the
normal operation current IIN.
A 3k3 for a 3.3V µC or 5k6 for a 5V µC is recommended.
For detailed calculation please refer to “Dimensioning of serial Resistor at IN pin” on Page 24.
Figure 14 Readout of feedback information and XOR logic in micro
7.2 Adjustable Slew Rate
In order to optimize electromagnitic emission, the switching speed of the MOSFET can be adjusted by
connecting an external resistor between SRP pin and GND. This allows for balancing between electromagnetic
emissions and power dissipation. RSRP-min represents the minimum slew rate Slew ratemin and RSRP-max
represents the maximum slew rate Slew ratemax.
A short to GND causes the minimum Slew ratemin.
Open pin condition causes the maximum Slew ratemax.
Figure 15 shows the relation between the resistor value and the slew rate of BTS3256D.
IN/Fault
BTS3256
Micro
controller
V
CC
V
S
GND
GND
DO
DI
V
DI
I
DO
I
IN
R1
V
CC
GND
V
bb
=1
0
0
0
Fault
Fault_readout.emf
Datasheet 19 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Control and Diagnosis
7.3 Electrical Characteristics - Diagnostic
Figure 15 Typical relation between slew rate and resistor values used on RSRP (Vbat=13.5V)
Table 7 Electrical Characteristics - Diagnostic
Parameter Symbol Values Unit Note or
Test Condition
Number
Min. Typ. Max.
Slew rate control
Slew ratemin Slew ratemin 0.08 0.2 0.6 V/µs RSRP = 0 Ω
VS = 13.5 V;
ohmic load
P_7.3.1
Slew rate15k Slew rate15k 0.2 0.6 – V/µs RSRP = 15 kΩ
VS = 13.5 V;
ohmic load
P_7.3.2
Slew rate30k Slew rate30k 0.7 1.45 – V/µs RSRP = 30 kΩ
VS = 13.5 V;
ohmic load
P_7.3.3
Slew ratemax Slew ratemax 1.2 2.2 3.8 V/µs SRP pin open
VS = 13.5 V;
ohmic load
P_7.3.4
0
0,5
1
1,5
2
2,5
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
Slew rate [ V/µs ]
R
SRP
[ kΩ ]
Slewrate.emf
Datasheet 20 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Protection Functions
8 Protection Functions
The device provides embedded protection functions against over temperature, over load and short circuit.
Note: Integrated protection functions are designed to prevent IC destruction under fault conditions
described in the data sheet. Fault conditions are considered as “outside” normal operation.
8.1 Thermal Protection
The device is protected against over temperature resulting from overload and / or bad cooling conditions.
The BTS3256D has a thermal restart function. When overheating occurs, the device switches off for the restart
delay time trestart. After this time the device restarts if the temperature is below threshold and the IN has logic
high level. The fault feedback is activated during over temperature situation. See Figure 16 for the restart
behavior.
The diagram naming refers to Figure 14.
Figure 16 Status Feedback via Input Current at Over temperature
8.2 Over Voltage Protection
The BTS3256D is equipped with a voltage clamp mechanism that keeps the Drain-Source voltage VD at a
certain level. This stage is also used for inductive clamping.
See “Inductive Output Clamp” on Page 12 for details.
8.3 Short Circuit Protection
The condition short circuit is an overload condition of the device.
In a short circuit condition, the resulting dI / dt is a function of the short circuit resistance. The BTS3256D
incorporates 2 shut down strategies for maximum robustness in the presence of short circuits:
- immediate shut down in the case of low ohmic shorts by power detection exceeding Pmax
IN
Low
High
t
Therm al shutdown
low
high
t
t
TJ
T
JSD
IIN
IINnom
t
0
IIN fa u lt
ΔTJSD
After delay time , IN is high
Over temperature is gone
Don’t care
thermal_fault_autorestart.emf
VDI
trestart
Datasheet 21 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Protection Functions
- over temperature shut down in the case of an overload condition
The additional feature of this device is a limitation of the load current to Ilim for a maximum time of tlim.
If the condition is normalized in a shorter time than tlim, the device stays on, if not the device switch off for
trestart and tries to restart in case the IN pin is still high.
From first switch off the fault feedback will be activated during trestart and continues until the IN pin goes low
or normal condition is reached.
Figure 18 shows the behavior mentioned above. In this example first a shorted load occurs which causes the
device to limit the current. The device stays on, because the load current returns to normal condition before
trestart. In the second switch on, the short circuit is permanent and the device switches OFF after maximum
limiting time, stays OFF for the blanking time regardless of the input pin condition and then stays OFF
according to the IN pin low condition.
The definitions of voltages and currents are in respect to Figure 14. The behavior of VDI also depends on RIN.
Figure 17 Typical Power limitation behavior IDS / VDS
10
20
30
40
50
60
70
0102030
ID[ A ]
VDrain [ V ]
Power_limitation.emf
Safe operation area
Protective Shut Down
Datasheet 22 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Protection Functions
Figure 18 Short Circuit during On State, Typical Behavior for Ohmic Loads
The case when the device switches on into an existing short circuit - Short circuit type 1- is shown in Figure 17.
The test setup for short circuit characterization is shown in Figure 19. The BTS3256D is a low side switch.
Therefore it can be assumed that the micro controller and device GND connection have a low impedance. All
impedance in the short circuit path is merged in the short circuit resistance RSC and short circuit inductance
LSC.
Figure 19 Test Setup for Short Circuit Characterization Test
V
IN
low
high
Inrush
Overload
V
DI
low
high
I
D
I
lim
I
IN
I
INnom
0
I
IN fa u l t
I
Dnom
t
lim
Don’t care
Overload
situation
t
t
overload
shut off
protection_behaviour.emf
t
restart
t
lim
t
t
GND
Drain
BTS3 256
GND
V
bb
R
SC
L
SC
I
D
Control circuit
IN
V
S
Vcc
5V
SRP
sho rt_circuit_schem atic.emf
R
SRP
Datasheet 23 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Protection Functions
8.4 Electrical Characteristics - Protection
Table 8 Electrical Characteristics - Protection
Parameter Symbol Values Unit Note or
Test Condition
Number
Min. Typ. Max.
Thermal Protection
Thermal shut down junction
temperature
TJSD 150 1751)
1) Not subject to production test, specified by design.
–°C– P_8.4.1
Thermal hysteresis ∆TJSD –10–K
1) P_8.4.2
Over Voltage Protection
Drain source clamp voltage VD(AZ) 40 44 – V ID = 10 mA;
VS = 0.0 V;
VIN = 0.0 V
P_8.4.3
–4549VID = 8 A;
VS = 0.0 V;
VIN = 0.0 V
Short Circuit Protection
current limitation level ID(lim) 42 55 72 A ohmic load P_8.4.4
max. power switch OFF
threshold
Pmax 300 400 650 W – P_8.4.5
max. time before current
limitation before shut OFF
tlim 3.5 5 6.5 ms 2)
resistive load
2) In case of inductive loads the device needs to increase the VDS voltage during current limitation.
This can trigger the over Power protection switch off earlier as tlim.
P_8.4.6
reset delay time trestart 50 70 100 ms – P_8.4.7
Datasheet 24 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Application Information
9 Application Information
Note: The following information is given as a hint for the implementation of the device only and shall not
be regarded as a description or warranty of a certain functionality, condition or quality of the device.
9.1 Dimensioning of serial Resistor at IN pin
In order to use the digital feedback function of the device, there must be a serial resistor used between the IN
pin and the driver (micro controller).
To calculate this serial resistor on the input pin, three device conditions and of course the driver (micro
controller) abilities need to be taken into account.
Figure 20 shows the circuit used for reading out the digital status.
Figure 20 Circuitry to readout fault information
Note: This is a very simplified example of an application circuit. The function must be verified in the real
application.
Conditions to be meet by the circuitry:
During normal operation VIN must be higher than VINH,min to switch ON.
During fault condition the max. capability of the driver (micro controller) must not be exceeded and the logic
low level at DI must be ensured by a voltage drop over the serial resistor RIN while the device fault current is
flowing.
Conditions in formulas:
•µCoutput current,min > µCHIGH,max / RIN > IINFault_min
with µCoutput current,min referring to the µC maximum output current capability
with µCHIGH,max referring to the maximum high output voltage of the µC driving stage
This condition is valid during normal operation mode
IN/Fault
DO
DI
I
DO
I
IN
R
IN
1.0mA
:
3.0mA
20µA
:
100µA
Faul t i nfor mation
Micr ocontr oll er
BTS3256
V
RIN
GND
V
DO
V
DI
GND
V
CC
V
S
GND
V
CC
V
bb
Fault_R1dim.emf
R
SRP
SRP
Datasheet 25 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Application Information
•VIN = µCHIGH,min - (RIN * IIN,max) > VINH,min
with µCHIGH,min referring to the minimal high output voltage of the µC driving stage
This condition is valid during normal operation mode
•µCHIGH,max - (RIN * IIN-Fault,min) < µC(DI)L,max
with µC(DI)L,max referring to the maximum logic low voltage of the µC input stage
The maximumcurrent is either defined by the BTS3256D or the µC driving stage
This condition is valid during status feedback operation mode
Out of this conditions the minimum and maximum resistor values can be calculated.
For a typical 5V micro controller with output current capability in the 3 mA range,
a resistor range from 7.5 kΩ down to 4.5 kΩ can be used.
For a typical 3.3V micro controller a range from 4.6 kΩ to 2.5 kΩ is suitable.
9.2 Further Application Information
• For further information you may contact http://www.infineon.com/hitfet
Datasheet 26 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Package Outlines
10 Package Outlines
Figure 21 PG-TO-252-5-11
Green Product (RoHS compliant)
To meet the world-wide customer requirements for environmentally friendly products and to be compliant
with government regulations the device is available as a green product. Green products are RoHS-Compliant
(i.e Pb-free finish on leads and suitable for Pb-free soldering according to IPC/JEDEC J-STD-020).
For further information on alternative packages, please visit our website:
http://www.infineon.com/packages.Dimensions in mm
Datasheet 27 Rev. 1.1
2018-01-29
Smart Low Side Power Switch
BTS3256D
Revision History
11 Revision History
Version Date Changes
Rev. 1.1 2017-07-27 4.1.7 Footnote added “refer to Fig. 13”
4.2.1 Footnote added “refer to Fig. 19”
6.4.6 Standby supply current parameter added
Figure 21. Package outline updated
Rev. 1.0 2009-05-05 released Datasheet
Trademarks
All referenced product or service names and trademarks are the property of their respective owners.
Edition 2018-01-29
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2018 Infineon Technologies AG.
All Rights Reserved.
Do you have a question about any
aspect of this document?
Email: erratum@infineon.com
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hereby disclaims any and all warranties and liabilities
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