Standard Power
Data Sheet
Rev. 1.1, 2011-07-08
IFX91041
1.8A DC/DC Step-Down Voltage Regulator
5.0V, 3.3V or Adjustable Output Voltage
IFX91041EJV50
IFX91041EJV33
IFX91041EJV
PG-DSO-8-27
Type Package Marking
IFX91041EJV50 PG-DSO-8-27 I9104150
IFX91041EJV33 PG-DSO-8-27 I9104133
IFX91041EJV PG-DSO-8-27 I91041V
Data Sheet 2 Rev. 1.1, 2011-07-08
1.8A DC/DC Step-Down Voltage Regulator IFX91041
1Overview
• 1.8A step down voltage regulator
• Output voltage versions: 5.0 V, 3.3 V and adjustable
• ± 2% output voltage tolerance (+-4% for full load current range)
• Integrated power transistor
• PWM regulation with feedforward
• Input voltage range from 4.75V to 45V
• 370 kHz switching frequency
• Synchronization input
• Very low shutdown current consumption (<2uA)
• Soft-start function
• Input undervoltage lockout
• Suited for industrial applications: Tj = -40 °C to +125°C
• Green Product (RoHS compliant)
For automotive and transportation applications, please refer to the Infineon TLE and TLF voltage regulator series.
Description
The IFX91041 series are monolithic integrated circuits that provide all active functions for a step-down (buck)
switching voltage regulator, capable of driving up to 1.8A load current with excellent line and load regulation.
These devices are suited for use in industrial applications featuring protection functions such as current limitation
and overtemperature shutdown. Versions with a fixed 5.0V and 3.3V (IFX91041EJV50, IFX91041EJV33) output
voltage as well as an adjustable device (IFX91041EJV) with 0.60V reference feedback voltage are available. The
switching frequency of 370kHz allows to use small and inexpensive passive components. The IFX91041 features
an enable function reducing the shut-down current consumption to <2uA. The voltage mode regulation scheme of
this device provides a stable regulation loop maintained by small external compensation components. Besides
the feedforward control path offers an excellent line transient rejection. The integrated soft-start feature limits the
current peak as well as voltage overshot at start-up.
IFX91041
Block Diagram
Data Sheet 3 Rev. 1.1, 2011-07-08
2 Block Diagram
Figure 1 Block Diagram
8
2
GND
Enable
Oscillator
7
4
Buck
Converter
6
FB
BUO
3
COMP
IFX91041
1
SYNC
5
BDS
EN VS
Over
Temperature
Shutdown
Feedforward
Soft start ramp
generator
Bandgap
Reference
Charge Pump
Data Sheet 4 Rev. 1.1, 2011-07-08
IFX91041
Pin Configuration
3 Pin Configuration
3.1 Pin Assignment
Figure 2 Pin Configuration
3.2 Pin Definitions and Functions
Pin Symbol Function
1SYNCSynchronization Input.
Connect to an external clock signal in order to synchronize/adjust the switching frequency.
If not used connect to GND.
2GNDGround.
3COMP Compensation Input.
Frequency compensation for regulation loop stability.
Connect to compensation RC-network.
4FB Feedback Input.
For the adjustable output voltage versions (IFX91041EJV) connect via voltage divider to output
capacitor.
For the fixed voltage version (IFX91041EJV50, IFX91041EJV33) connect this pin directly to the
output capacitor.
5BDS Buck Driver Supply Input.
Connect the bootstrap capacitor between this pin and pin BUO.
6BUO Buck Switch Output.
Source of the integrated power-DMOS transistor. Connect directly to the cathode of the catch
diode and the buck circuit inductance.
7EN Enable Input.
Active-high enable input with integrated pull down resistor.
8VS Supply Voltage Input.
Connect to supply voltage source.
Exposed Pad Connect to heatsink area and GND by low inductance wiring.
GND EN
COMP BUO
VS
5
6
4
3
2 7
1 8
FB
IFX91041
SYNC
BDS
S08_ PIN.vsd
IFX91041
General Product Characteristics
Data Sheet 5 Rev. 1.1, 2011-07-08
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.
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 operating range. Protection functions are
not designed for continuous repetitive operation.
Absolute Maximum Ratings1)
Tj = -40 °C to +125°C; all voltages with respect to ground (unless otherwise specified)
1) Not subject to production test, specified by design.
Pos. Parameter Symbol Limit Values Unit Conditions
Min. Max.
Voltages
4.1.1 Synchronization Input VSYNC -0.3 5.5 V –
6.2 V t < 10s2)
2) Exposure to those absolute maximum ratings for extended periods of time (t > 10s) may affect device reliability
4.1.2 Compensation Input VCOMP -0.3 5.5 V –
4.1.3 6.2 V t < 10s1)
4.1.4 Feedback Input VFB -0.3 10 V IFX91041EJV50;
IFX91041EJV33
4.1.5 -0.3 5.5 V IFX91041EJV
4.1.6 Buck Driver Supply Input VBDS VBUO
- 0.3
VBUO
+ 5.5
V
4.1.7 Buck Switch Output VBUO -2.0 VVS + 0.3 V
4.1.8 Enable Input VEN -40 45 V
4.1.9 Supply Voltage Input VVS -0.3 45 V
Temperatures
4.1.10 Junction Temperature Tj-40 150 °C–
4.1.11 Storage Temperature Tstg -55 150 °C–
ESD Susceptibility
4.1.12 ESD Resistivity VESD -2 2 kV HBM 3)
3) ESD susceptibility HBM according to EIA/JESD 22-A 114B (1.5kΩ,100pF).
Data Sheet 6 Rev. 1.1, 2011-07-08
IFX91041
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
Pos. Parameter Symbol Limit Values Unit Conditions
Min. Max.
4.2.1 Supply Voltage VS4.75 45 V –
4.2.2 Output Voltage adjust range VCC 0.60 16 V IFX91041EJV
4.2.3 Buck inductor LBU 18 56 µH –
4.2.4 Buck capacitor CBU1 33 120 µF –
4.2.5 Buck capacitor ESR ESRBU1 –0.3Ω– 1)
1) See section ““Application Information” on Page 12” for loop compensation requirements.
4.2.6 Junction Temperature Tj-40 125 °C–
Pos. Parameter Symbol Limit Values Unit Conditions
Min. Typ. Max.
4.3.1 Junction to Case1)
1) Not subject to production test, specified by design.
RthJC ––12K/W–
4.3.2 Junction to ambient1) RthJA –52–K/W
2)
2) According to Jedec JESD52-1,-5,-7 at natural convection on 2s2p FR4 PCB for 1W power dissipation. PCB
76.2x114.3x1.5mm3 with 2 inner copper layers of 70µm thickness. Thermal via array conected to the first inner copper layer
under the exposed pad.
IFX91041
Buck Regulator
Data Sheet 7 Rev. 1.1, 2011-07-08
5 Buck Regulator
5.1 Description
The gate of the power switch is driven by the external capacitor connected to pin BDS (Buck Driver Supply) using
the bootstrap principle. An integrated under voltage lockout function supervising the ’bootstrap’ capacitor voltage
ensures that the device is always driven with a sufficient bootstrap voltage in order to prevent from extensive heat
up of the power transistor. An integrated charge pump supports the gate drive in case of low input supply voltage,
small differential voltage between input supply and output voltage at low current and during startup. In order to
minimize emission, the charge pump is switched off if the input voltage is sufficient for supplying the bootstrap.
The soft start function generates a defined ramp of the output voltage during the first 0.5 ms (typ.) after device
initialization. The device initialization is triggered either by the EN voltage level crossing the turn-on threshold,
rising supply voltage (during EN=H), and also when the device restarts a after thermal shutdown. The ramp starts
after the BDS external capacitor is charged.
The regulation scheme uses a voltage controlled pulse width modulation with feed forward path (the feed forward
operates for supply voltages from 8.0V to 36V) which provides a fast line transient reaction.
In order to maintain the output voltage regulation even under low duty cycle conditions (light load conditions down
to ICC=0mA, high input voltage) a pulse skipping operation mode is implemented. Pulse skipping is also used for
operation with low supply voltages, related to high duty cycles >92%
In case of a lost connection to the pin FB , an internal pull-up current prevents from a uncontrolled rise of the output
voltage (version IFX91041EJV only).
Figure 3 Block Diagram Buck Regulator
t
f
t
r
t
r
Schmitt-Trigger 1
V
high
V
low
t
Ramp
SYNC
&
&
RQ
S
OFF
when H
Q
Clock
>1
_
Error -FF
L when
T
j> 175 °C
Error
Amp.
FB
COMP
Error -Signal
Error -Ramp
PWM
Comp. H when
Error-Signal <
Error -Ramp
Output Stage
OFF when H
NOR1
L when Overcurrent
&
NAND 2
&
&
RQ
S
H =
OFF
Q
PWM-FF
1
INV H =
ON
Gate
Driver
Gate Driver
Supply
Power
D-MOS
BUO
BDS
OC
Comp.
=
V
S
BDS
UV Comp.
H when
UV at
V
BDS
Charge
Pump
=
t
r
t
r
t
f
Oscillator
V
max
V
min
t
Soft start
Ramp
Generator
V
Ref
0.6 V =
ΔV=k
X
V
S
Feedforward
L when
Output
overvoltage
Data Sheet 8 Rev. 1.1, 2011-07-08
IFX91041
Buck Regulator
5.2 Electrical Characteristics
Electrical Characteristics: Buck Regulator
VS = 6.0 V to 40 V, Tj = -40 °C to +125°C, all voltages with respect to ground (unless otherwise specified)
Pos. Parameter Symbol Limit Values Unit Conditions
Min. Typ. Max.
5.2.1 Output voltage VFB 4.90 5.00 5.10 V IFX91041EJV50;
VVEN = VS
0.1A < ICC < 1.0A
5.2.2 VFB 4.80 5.00 5.20 V IFX91041EJV50;
VVEN = VS;
1mA < ICC < 1.8A
5.2.3 Output voltage VFB 3.23 3.30 3.37 V IFX91041EJV33;
VVEN = VS;
0.1A < ICC < 1.0A
5.2.4 VFB 3.17 3.30 3.43 V IFX91041EJV33;
VVEN = VS;
1mA < ICC < 1.8A
5.2.5 Output voltage VFB 0.588 0.60 0.612 V IFX91041EJV;
VVEN = VS;
FB connected to VCC;
VS = 12V
0.1A < ICC < 1.0A
5.2.6 VFB 0.576 0.60 0.624 V IFX91041EJV;
VVEN = VS;
FB connected to VCC;
VS = 12V
1mA < ICC < 1.8A
5.2.7 Minimum output load requirement ICC,MIN 0 – – mA IFX91041EJV501)
5.2.8 1 – – mA IFX91041EJV331)
5.2.9 1.5 mA IFX91041EJV
VCC ?> 3V1)
5.2.10 5 mA IFX91041EJV
VCC ?> 1.5V1)
5.2.11 10 – – mA IFX91041EJV
VCC ?> =0.6V1)
5.2.12 FB input current IFB -1 -0.1 0 µA IFX91041EJV
VFB = 0.6V
5.2.13 FB input current IFB – – 900 µA IFX91041EJV50,
IFX91041EJV33
5.2.14 Power stage on-resistance Ron –– 500mΩtested at 300 mA
5.2.15 Current transition rise/fall time tr–50– nsICC=1 A 2)
5.2.16 Buck peak over current limit IBUOC 2.2 – 3.6 A –
5.2.17 Bootstrap under voltage lockout,
turn-off threshold
VBDS,off VBUO
+3.3
– – V Bootstrap voltage
decreasing
5.2.18 Charge pump current ICP 2– – mAVS = 12V;
VBUO = VBDS = GND
IFX91041
Buck Regulator
Data Sheet 9 Rev. 1.1, 2011-07-08
5.2.19 Charge pump switch-off threshold VBDS -
VBUO
–– 5 V(VBDS - VBUO) increasing
5.2.20 Maximum duty cycle Dmax –– 100%
3)
5.2.21 Soft start ramp tstart 350 500 750 µs VFB rising from 5% to
95% of VFB,nom
5.2.22 Input under voltage shutdown
threshold
VS,off 3.75 – – V VS decreasing
5.2.23 Input voltage startup threshold VS,on – – 4.75 V VS increasing
5.2.24 Input under voltage shutdown
hysteresis
VS,hyst 150 – – mV –
1) Not subject to production test, application related parameter
2) Not subject to production test; specified by design.
3) Consider “Chapter 4.2, Functional Range”
Electrical Characteristics: Buck Regulator
VS = 6.0 V to 40 V, Tj = -40 °C to +125°C, all voltages with respect to ground (unless otherwise specified)
Pos. Parameter Symbol Limit Values Unit Conditions
Min. Typ. Max.
Data Sheet 10 Rev. 1.1, 2011-07-08
IFX91041
Module Enable and Thermal Shutdown
6 Module Enable and Thermal Shutdown
6.1 Description
With the enable pin the device can be set in off-state reducing the current consumption to less than 2µA.
The enable function features an integrated pull down resistor which ensures that the IC is shut down and the power
switch is off in case the pin EN is left open.
The integrated thermal shutdown function turns the power switch off in case of overtemperature. The typ. junction
shutdown temperature is 175°C, with a min. of 160°C. After cooling down the IC will automatically restart
operation. The thermal shutdown is an integrated protection function designed to prevent IC destruction when
operating under fault conditions. It should not be used for normal operation.
6.2 Electrical Characteristics Module Enable, Bias and Thermal Shutdown
Electrical Characteristics: Enable, Bias and Thermal Shutdown
VS = 6.0 V to 40 V, Tj = -40 °C to +125°C, all voltages with respect to ground (unless otherwise specified)
Pos. Parameter Symbol Limit Values Unit Conditions
Min. Typ. Max.
6.2.1 Current Consumption,
shut down mode
Iq,OFF –0.12µAVEN = 0.8V;
Tj < 105°C; VS = 16V
6.2.2 Current Consumption,
active mode
Iq,ON ––7mAVEN = 5.0V; ICC = 0mA;
VS = 16V
FB connected to VOUT
6.2.3 Current Consumption,
active mode
Iq,ON ––10mAVEN = 5.0V; ICC = 1.8A;
VS = 16V
FB connected to VOUT
1)
6.2.4 Enable high signal valid VEN,lo 3.0 – – V –
6.2.5 Enable low signal valid VEN,hi ––0.8V–
6.2.6 Enable hysteresis VEN,HY 50 200 400 mV 1)
1) Specified by design. Not subject to production test.
6.2.7 Enable high input current IEN,hi ––30µAVEN = 16V
6.2.8 Enable low input current IEN,lo –0.11µAVEN = 0.5V
6.2.9 Over temperature shutdown Tj,sd 160 175 190 °C 1)
6.2.10 Over temperature shutdown
hysteresis
Tj,sd_hyst –15–K
1)
IFX91041
Module Oscillator
Data Sheet 11 Rev. 1.1, 2011-07-08
7 Module Oscillator
7.1 Description
The oscillator turns on the power switch with a constant frequency while the buck regulating circuit turns the power
transistor off in every cycle with an appropriate time gap depending on the output and input voltage.
The internal sawtooth signal used for the PWM generation has an amplitude proportional to the input supply
voltage (feedforward).
The turn-on frequency can optionally be set externally via the ’SYNC’ pin using a TTL compatible input signal. In
this case the synchronization of the PWM-on signal refers to the falling edge of the ’SYNC’-pin input signal. In case
the synchronization to an external clock signal is not needed the ’SYNC’ pin should be connected to GND.
Leaving pin SYNC open or short-circuiting it to GND leads to normal operation with the internal switching
frequency.
7.2 Electrical Characteristics Module Oscillator
Electrical Characteristics: Buck Regulator
VS = 6.0 V to 40 V, Tj = -40 °C to +125°C, all voltages with respect to ground (unless otherwise specified)
Pos. Parameter Symbol Limit Values Unit Conditions
Min. Typ. Max.
7.2.1 Oscillator frequency fosc 330 370 420 kHz VSYNC = 0V
7.2.2 Synchronization capture range fsync 200 530 kHz
7.2.3 SYNC signal high level valid VSYNC,hi 2.9 V 1)
1) Synchronization of PWM-on signal to falling edge.
7.2.4 SYNC signal low level valid VSYNC,lo 0.8 V 1)
7.2.5 SYNC input internal pull-down RSYNC 0.60 1.0 1.4 MΩVSYNC = 5V
Data Sheet 12 Rev. 1.1, 2011-07-08
IFX91041
Application Information
8 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.
8.1 Frequency Compensation
The stability of the output voltage can be achieved with a simple RC connected between pin COMP and GND. The
standard configuration using the swiching frequency of the internal oscillator is a ceramic capacitor CCOMP =22nF
and RCOMP =22kΩ. By slight modifications to the compensation network the stability can be optimized for different
application needs, such as varying switching frequency (using the sychronizing function), different types of buck
capacitor (ceramic or tantalum) etc.
The compensation network is essential for control loop stability. Leaving pin COMP open might lead to instable
operation.
8.2 Compensating a tantalum buck capacitor CBU1
The TLE control loop is optimized for ceramic buck capacitors CBU. In order to maintain stability also for tantalum
capacitors with ESR up to 300mΩ, an additional compensation capacitance CCOMP2 at pin COMP to GND is
required. It’s value calculates:
CCOMP2 = CBU * ESR(CBU) / RCOMP ,
whereas CCOMP2 needs to stay below 5nF.
Figure 4 High-ESR buck capacitor compensation
8.3 Catch Diode
In order to minimize losses and for fast recovery, a schottky catch diode is required. Disconnecting the catch diode
during operation might lead to destruction of the IC.
2
GND
3
COMP
IFX91041
C
COMP
R
COMP
C
COMP2
Application _C-COMP2.vsd
IFX91041
Application Information
Data Sheet 13 Rev. 1.1, 2011-07-08
8.4 IFX91041EJV50, IFX91041EJV33 with fixed Output Voltage
Figure 5 Application Diagram IFX91041EJV50 or IFX91041EJV33
Note: This is a very simplified example of an application circuit. The function must be verified in the real application
V
Batt
V
OUT
D
1
L
I
22…47µH
Ignition Key
Terminal 15
L
BU
C
BU1
D
BU
47µH
100µF
C
BU2
220nF
220nF
C
BOT
8
2
GND
Enable
Oscillator
7
4
Buck
Converter 6
FB
BUO
3
COMP
IFX91041EJV50
IFX91041EJV33
1
SYNC
5
BDS
EN VS
Over
Temperature
Shutdown
Feedforward
Soft start ramp
generator
Bandgap
Reference
C
COMP
Charge Pump
R
COMP
Data Sheet 14 Rev. 1.1, 2011-07-08
IFX91041
Application Information
8.5 Adjustable Output Voltage Device
Figure 6 Application Diagram IFX91041EJV
Note: This is a very simplified example of an application circuit. The function must be verified in the real application
The output voltage of the IFX91041EJV can be programmed by a voltage divider connected to the feedback pin
FB. The divider cross current should be 300 µA at minimum, therefore the maximum R2 calculates:
R2 ≤ VFB / IR2 --> R2 ≤ 0.6V / 300 µA = 2 kΩ
For the desired output voltage level VCC, R1 calculates then (neglecting the small FB input current):
Add a 0.5 nF capacitor close to FB pin.
V
Batt
V
OUT
D
1
L
I
22…47µH
Ignition Key
Terminal 15
L
BU
C
BU1
D
BU
47µH
100µF
C
BU2
220nF
220nF
C
BOT
R
1
R
2
8
2
GND
Biasing &
Enable
Oscillator
7
4
Buck
Converter
6
FB
BUO
3
COMP
IFX91041EJV
1
SYNC
5BDS
EN VS
Over
Temperature
Shutdown
Feedforward
Soft start ramp
generator
Bandgap
Reference
C
COMP
Charge Pump
R
COMP
C
FB
R1R2
VCC
VFB
---------- 1–
⎝⎠
⎛⎞
.=
IFX91041
Package Outlines
Data Sheet 15 Rev. 1.1, 2011-07-08
9 Package Outlines
Figure 7 Outline PG-DSO-8-27
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 package information, please visit our website:
http://www.infineon.com/packages.Dimensions in mm
Data Sheet 16 Rev. 1.1, 2011-07-08
IFX91041
Revision History
10 Revision History
Rev.1.1 2011-07-08 Adjustment of Junction Temperature Range in (4.2.6) “Functional Range” on Page 6 to
the conditions used in the “Electrical Characteristics” on Page 8 ff (-40°C to 125°C)
Rev.1.02 2010-02-23 Editorial change
Rev.1.01 2009-10-19 Overview page: Inserted reference statement to TLE/TLF series.
Rev.1.0 2009-05-04 Final data sheet
Edition 2011-07-08
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2011 Infineon Technologies AG
All Rights Reserved.
Legal Disclaimer
The information given in this document shall in no event be regarded as a guarantee of conditions or
characteristics. With respect to any examples or hints given herein, any typical values stated herein and/or any
information regarding the application of the device, Infineon Technologies hereby disclaims any and all warranties
and liabilities of any kind, including without limitation, warranties of non-infringement of intellectual property rights
of any third party.
Information
For further information on technology, delivery terms and conditions and prices, please contact the nearest
Infineon Technologies Office (www.infineon.com).
Warnings
Due to technical requirements, components may contain dangerous substances. For information on the types in
question, please contact the nearest Infineon Technologies Office.
Infineon Technologies components may be used in life-support devices or systems only with the express written
approval of Infineon Technologies, if a failure of such components can reasonably be expected to cause the failure
of that life-support device or system or to affect the safety or effectiveness of that device or system. Life support
devices or systems are intended to be implanted in the human body or to support and/or maintain and sustain
and/or protect human life. If they fail, it is reasonable to assume that the health of the user or other persons may
be endangered.