IRF IRS279524STRPBF Programmable minimum and maximum switching frequency Datasheet

IRS27951S
IRS27952(4)S
RESONANT HALF-BRIDGE CONVERTER CONTROL IC
Features
•
•
•
•
•
•
•
•
•
•
•
•
Simple primary-side control solution for fixed and variable
frequency DC-DC resonant converters.
Max 500kHz per channel output with 50% duty cycle
Floating channel bootstrap operation up to +600Vdc
Programmable minimum and maximum switching frequency
Programmable soft start frequency and soft start time
Programmable dead time
Micropower start-up & ultra low quiescent current
Over-current protection using low side MOSFET Rds(on)
User initiated micropower “Sleep mode”
Under-voltage Lockout
Simple design with minimal component count.
Lead-free
Product Summary
Topology
Half-Bridge
VOFFSET
600 V
VOUT
VCC
IO+ & IO- (typical)
300 mA & 900 mA
Dead-time
(programmable)
200ns~2us
Package Options
Typical Application
•
•
•
LCD & PDP TV
Telecom SMPS, PC SMPS
Home Audio Systems
IRS27951S/IRS27952S
14-lead SOIC
IRS279524S
Ordering Information
Standard Pack
Base Part Number
IRS27951
IRS27952
IRS279524
1
www.irf.com
Package Type
SOIC8N
SOIC8N
SOIC14N
Complete Part Number
Form
Quantity
Tube/Bulk
95
IRS27951SPBF
Tape and Reel
2500
IRS27951STRPBF
Tube/Bulk
95
IRS27952SPBF
Tape and Reel
2500
IRS27952STRPBF
Tube/Bulk
55
IRS279524SPBF
Tape and Reel
2500
IRS279524STRPBF
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Typical Application Diagram
DC BUS
VIN
R1
R2
Rcc
D3
Dbs
1
CDC
2
3
4
Dss
Rss
RT
Cbs
U1
VCC
VB
RT
HO
CT/SD
VS
COM
LO
8
M1
Rg1
D1
7
6
5
Lr
IRS2795
M2
Rg2
Rmax
CT
Css
LOAD
COUT
D2
Cr
RTN
Rled
Rbias
Rs1
Cf1
U2
Cf2
Rf2
U3
TL431
Rs2
2
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Table of Contents
Page
Ordering Information
1
Typical Application Diagram
2
Absolute Maximum Ratings
5
Recommended Operating Conditions
5
Electrical Characteristics
6
Functional Block Diagram
8
Input/Output Pin Equivalent Circuit Diagram
9
Lead Definitions
10
Lead Assignments
10
State Diagram
12
Application Information and Additional Details
13
Package Details
23
Tape and Reel Details
25
Part Marking Information
27
Qualification Information
28
3
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Description
The IRS2795(1,2)(4) is a self oscillating half-bridge driver IC for DC-DC resonant converter applications, especially
the LLC resonant half-bridge converter. The frequency and dead time can be programmed externally using two
external components. The IC offers over current protection using the on state resistance of the low-side MOSFET.
The IC can be disabled by externally pulling the voltage at the CT/SD pin below its enable voltage threshold
4
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Absolute Maximum Ratings
Absolute maximum ratings indicate sustained limits beyond which damage to the device may occur. All voltage
parameters are absolute voltages referenced to COM, all currents are defined positive into any lead. The thermal
resistance and power dissipation ratings are measured under board mounted and still air conditions.
Symbol
VCC
VB
VS
VHO
VLO
VCT
VRT
IRT
dVs/dt
TJ
TS
PD
RthJA
Definition
Supply Voltage
High-side Floating Supply Voltage
High-side Floating Supply Offset Voltage
High-side Floating Output Voltage
Low-side Output Voltage
CT/SD Pin Voltage
RT Pin Voltage
RT pin source current
Allowable offset voltage slew rate
Operating Junction Temperature
Storage Temperature
Package power dissipation @ TA ≤
25°C
Thermal resistance, junction to
ambient
(8 lead SOIC)
(14 lead SOIC)
(8 lead SOIC)
(14 lead SOIC)
Min.
Max.
-0.3
-0.3
VB – 25
VS – 0.3
-0.3
-0.3
-0.3
---50
-40
-55
—
—
—
—
25
625
VB + 0.3
VB + 0.3
VCC + 0.3
VCC + 0.3
VCC + 0.3
2
50
150
150
0.833
1.04
150
120
Units
V
mA
V/ns
°C
W
°C/W
Recommended Operating Conditions
For proper operation the device should be used within the recommended conditions.
Symbol
Definition
Min.
Max.
Units
VBS
High-side floating supply voltage
10
Vcc
†
VS
Steady-state high-side floating supply offset voltage
600
V
-3.0
VCC
Supply voltage
12
18
fsw
Switching Frequency
--500
kHz
†
Care should be taken to avoid output switching conditions where the VS node flies inductively below ground by
more than 5 V.
Recommended Component Values
Symbol
RRT
CCT
5
Component
RT pin resistor value
CT pin capacitor value
www.irf.com
© 2012 International Rectifier
Min.
2
200
Max.
100
2000
Units
kΩ
pF
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Electrical Characteristics
VCC=VBS=15V, VS=0V, CVCC=CBS=0.1uF, CLO=CHO=1nF, RT=50.5kΩ, CT=200pF and TA = 25°C unless
otherwise specified. The output voltage and current (VO and IO) parameters are referenced to COM and are
applicable to the respective HO and LO output leads.
Symbol
Definition
Low Voltage Supply Characteristics
Min
Typ
Max
Units
Test Conditions
V
N/A
µA
VCC = VCCUV+
-0.1V
VCCUV+
VCC turn on threshold
10.1
11
11.9
VCCUV-
VCC turn off threshold
(Under Voltage Lock Out)
8.1
9
9.9
VCCUVHYS
VCC undervoltage lockout hysteresis
---
2
---
ICCSTART
VCC startup current
---
50
100
Sleep mode VCC supply current
---
150
200
VCT/SD<VEN2, VBS=0V
Quiescent VCC supply current
---
2
2.5
VEN1 < VCT/SD < 4.5V
ICC46KHz
VCC operating current @ fosc = 46KHz
---
3.1
4.5
ICC285KHz
VCC operating current @ fosc = 285KHz
---
8.7
11
7.6
8.5
9.4
ISLEEP
IQCC
Floating Supply Characteristics
VBS turn on threshold
VBSUV+
VBS turn on threshold
(Under Voltage Lock Out)
VBS undervoltage lockout hysteresis
7
7.9
8.8
---
0.6
---
VS Offset supply leakage current
---
---
50
VBS startup current
---
50
100
Quiescent VBS supply current
---
50
100
IBS46KHz
VBS operating current @ fosc = 46KHz
---
1
1.5
IBS285KHz
VBS operating current @ fosc = 285KHz
---
5.7
7
44.3
46.6
48.9
271
285
299
VBSUVVBSUVHYS
ILKVS
IBSSTART
IQBS
mA
RT=50.5kΩ
RT=7.32kΩ
V
N/A
VB = VS = 600 V
µA
VBS ≤ VBSUV+ - 0.1V
VEN1 < VCT/SD < 4.5V
mA
RT=50.5kΩ
RT=7.32kΩ
Oscillator I/O Characteristics
fSW
Oscillator frequency
kHz
CT=200pF,
RT=50.5kΩ
CT=200pF,
RT=7.32kΩ
V
GBD
VCT/SD < VEN1
VCT+
Upper CT ramp voltage threshold
---
5.0
---
VCT-
Lower CT ramp voltage threshold
---
3.0
---
CT/SD pin startup current
---
10
---
µA
1.92
2.0
2.08
V
---
1
---
A/A
--170
50
210
--250
%
ns
ICTSTART
VRT
Voltage reference at RT pin
CM
Current mirror ratio
D
Output duty cycle (LO and HO)
tDT
High/low output dead time
6
www.irf.com
© 2012 International Rectifier
CT=200pF
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Electrical Characteristics
VCC=VBS=15V, VS=0V, CVCC=CBS=0.1uF, CLO=CHO=1nF, RT=50.5kΩ, CT=200pF and TA = 25°C unless
otherwise specified. The output voltage and current (VO and IO) parameters are referenced to COM and are
applicable to the respective HO and LO output leads.
Symbol
Definition
Protection Characteristics
Min
Typ
Max
RRTD
RT discharge resistance
---
115
---
RCTD
CT/SD discharge resistance
---
115
---
VEN1
CT/SD rising enable voltage
0.75
1.05
1.4
VEN2
CT/SD standby voltage
0.6
0.85
1.1
CT/SD enable hysteresis voltage
---
0.2
---
1.9
2
2.1
3
300
3.15
---
VENHYST
VOCP
Overcurrent VS threshold
tBLANK
Leading edge blanking on LO
2.85
---
tSD
Shutdown propagation delay
---
300
---
Units
Test Conditions
Ω
V
V
ns
IRS27951
IRS27952(4)
GBD
GBD
Gate Driver Output Characteristics
VOH
Gate High Voltage
Vcc-1
---
---
VOL
Gate Low Voltage
---
0.05
0.15
tr
Output rise time
---
60
---
tr
Output rise time
---
200
---
tf
Output fall time
---
16
---
tf
Output fall time
---
65
---
MDT
Output deadtime matching
|(DTLO-HO) – (DTHO-LO)|
---
---
25
IO+
Output source current
---
300
---
IO-
Output sink current
---
900
---
RUP
Pull up Resistance
---
20
---
Pull down Resistance
---
3
---
RDOWN
†
V
IGATE = 20mA
IGATE = -20mA
CLOAD=1nF
ns
CLOAD=4.7nF
CLOAD=1nF
CLOAD=4.7nF
ns
mA
Ω
GBD
IGATE = 20mA
IGATE =-20mA
GBD: Guaranteed by design.
7
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Functional Block Diagram
VB
dv/DT
BOOSTER
HV LEVEL
SHIFTER
2V
RT
+
-
CURRENT FAULT LOGIC
& CONTROL
UVBS
S
Q
R
Q
HO
VS
Dead Time
CT/SD
OSCILLATOR
PULSE STEERING
VCC
UV DETECTION
DELAY
MATCH
LO
SLEEP MODE LOGIC
8
www.irf.com
© 2012 International Rectifier
COM
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Input/Output Pin Equivalent Circuit Diagrams:
VCC
VB
ESD
Diode
ESD
Diode
RT
RESD
25V
HO
ESD
Diode
ESD
Diode
COM
VS
600V
VCC
VCC
ESD
Diode
ESD
Diode
CT
ESD
Diode
RESD
RESD
LO
25V
ESD
Diode
COM
COM
9
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Lead Definitions:
Symbol
VCC
RT
CT/SD
COM
LO
VS
HO
VB
Description
Supply Voltage
Oscillator timing resistor
Oscillator timing capacitor / shutdown
Ground
Low-side gate drive
High-side gate drive return / HV current Sense
High-side gate drive
High-side floating supply voltage
Lead Assignments: IRS2795(1,2)S
1
VCC
VB
8
2
RT
HO
7
3
CT/SD
VS
6
4
COM
LO
5
1
NC
NC
14
2
VCC
VB
13
3
RT
HO
12
4
CT/SD
VS
11
5
COM
NC
10
6
NC
NC
9
7
NC
LO
8
Lead Assignments: IRS279524S
10
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
VCC: Power Supply Voltage
This is the supply voltage pin of the IC and sense node for the under-voltage lock out circuit. It is possible to turn off
the IC by pulling this pin below the minimum turn off threshold voltage, VCCUV- without damage to the IC. This pin is
not internally clamped.
RT: Oscillator timing resistor
This pin provides a precise 2V reference and a resistor connected from this pin to COM defines a current that is
used to set the minimum oscillator frequency. To close the feedback loop that regulates the converter output
voltage by modulating the oscillator frequency, the phototransistor of an optocoupler will be connected to this pin
through a resistor. The value of this resistor will set the maximum operating frequency. An R-C series connected
from this pin to COM sets frequency shift at start-up to prevent excessive energy inrush (soft-start).
CT/SD: Oscillator timing capacitor /Shutdown
An external capacitor CT from this pin to COM sets the dead time and frequency of the oscillator. The CT pin has
sawtooth waveform, which is charged up by the current reference programmed at RT pin during rising slope and is
discharged by an internal fixed 2mA current source during the falling slope. The falling time of the sawtooth defines
the dead-time.
At start-up, a 10uA current source charges this capacitor and the oscillator is enabled only when the voltage at this
pin exceeds VEN1. The IC can also be used to enter sleep mode by externally pulling this pin below VEN2.
COM: Logic and Gate drive Ground
This is ground potential pin of the integrated control circuit. All internal circuits are referenced to this point.
LO: Low-side Gate Drive Output
The driver is capable of 0.3A source and 0.9A sink peak current to drive the lower MOSFET of the half-bridge leg.
The pin is actively pulled to GND during UVLO.
VS: High Side Gate Return/Current Sense
This is the floating supply return. This pin also acts as a high voltage current sense pin and uses the low-side
MOSFET RDSON to detect an over current fault condition.
HO: High-side Gate Drive
The driver is capable of 0.3A source and 0.9A sink peak current to drive the high-side MOSFET in the half-bridge. A
resistor internally connected to pin VS ensures that the pin is not floating during UVLO.
VB: High Side floating supply voltage
The bootstrap capacitor connected between this pin and VS is charged by the bootstrap diode when the low-side
gate-drive is high.
11
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
State Diagram
DC POWER ON
Gate Inactive
Oscillator Inactive
UVLO
VCC < VCCUV-
Oscillator Inactive
Gates Inactive
VCC < VCCUVVCC > VCCUV+
SLEEP
CURRENT FAULT
Oscillator and Gates Inactive
ICT = ICTSTART
ICC=ISLEEP
Oscillator and Gates Inactive
Internally discharge RT and CT pins
VCT < VEN2
VCT > VEN1
NORMAL
VS > VOCP
@ LO=High
Oscillator and Gates Active
ICTCHARGE=IRT
Over Current Protection Active
UVLO Mode
The IC remains in the UVLO condition until the voltage on the VCC pin exceeds the VCC turn on threshold voltage,
VCCUV+. During the time the IC remains in the UVLO state, the gate drive circuit is inactive and the IC draws a
quiescent current of ICC START. The UVLO mode is accessible from any other state of operation whenever the IC
supply voltage condition of VCC < VCC UV- occurs.
Sleep Mode
When VCC exceeds the VCCUV+ threshold the IRS2795(1,2)(4) starts to charge up CT capacitor with ICT startup
current towards the enable threshold, VEN1. During this period, the IC is in Sleep mode. The oscillator and gate
drive circuits are disabled and the Ic consumes ISLEEP.
When the voltage at the CT/SD pin exceeds VEN1, the IC is pulled out of sleep mode and the 2V reference voltage
at the RT pin is enabled.
The IC can be placed in Sleep mode while operating in Normal mode by externally pulling the CT/SD pin below
VEN2. When this occurs, the RT pin of the IC is internally discharged to COM to ensure a system restart with softstart.
Normal Mode
The IC enters in normal operating mode once the UVLO voltage and VEN1 has been exceeded. The RT pin
voltage is 2V under normal mode. Gate drive signal appears at HO and LO with fixed 50% duty-cycle.
During this mode, the over-current protection scheme using the VS sense circuitry is active.
Current Fault Mode
When operating in Normal mode, the IC senses the voltage on the VS pin each time the low-side device is turned
ON (with a leading edge blanking on LO, tblank). When the voltage sensed exceeds VOCP, the IC terminates the
current gate pulse, disables the oscillator and gate drivers, and enters the Current Fault mode. When the IC
enters this state, RT and CT/SD pins are internally discharged and IC supply voltage must be recycled before the
IC can restart with soft-start again
12
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Application Information and Additional Details
Information regarding the following topics is included as subsections within this section of the datasheet.
•
•
•
•
•
•
•
•
•
General Description
IC Supply Circuit & Low start-up current
Multi-function 2 Pin Oscillator
Frequency and Dead-time Calculation
User initiated Micropower Sleep mode
Gate Drive Capability
System Protection Features
PCB Layout Tips
Additional Documentation
General Description
The IRS2795(1,2)(4) is a double-ended controller for the resonant half-bridge topology. It provides complementary
outputs with 50% (max) duty cycle; the high-side and low-side bridge devices are driven 180° out-of-phase for
exactly the same time. A programmable dead-time inserted between the turn-OFF of one switch and the turn-ON of
the other one guarantees soft-switching operation. The IC incorporates a multi-function oscillator that allows the
designer to program all the necessary features to control a half bridge resonant switch-mode power supply featuring
low standby power. The IC also incorporates additional protection features for robust operation and provides a high
performance solution while minimizing external components, design time, and printed circuit board real estate.
The IC enables the designer to externally program all the following features using a 2 pin RC oscillator – operating
frequency range (start-up, minimum and maximum frequency), dead time, soft-start time and sleep mode operation.
IRS2795(1,2)(4) also uses IR’s proprietary high-voltage technology to implement a VS sensing circuitry that
monitors the current through the low-side half bridge MOSFET for short circuit faults. By using the RDSON of the lowside MOSFET, the IRS2795(1,2)(4) eliminates the need for an additional current sensing resistor, filter and currentsensing pin. This protection feature is latched and the thresholds are fixed at 2V for IRS27951 and 3V for
IRS27952(4).
Finally, the controller IC also features a micro power startup current (ICC<100µA) and a user initiated sleep mode
during which the IC power consumption is less than 200µA (@ Vcc=15V). The sleep mode function allows system
designs with reduced standby power consumption and can be used to meet stringent energy standards from Blue
Angel, Energy Star etc.
IC Supply Circuit & Low start-up current
The UVLO circuit maintains the IC in UVLO mode if the VCC pin voltage is less than the VCC turn-on threshold,
VCCON. If the VCC pin voltage drops below the UVLO threshold VCCUVLO at anytime after start-up, the IC is
pushed back into UVLO mode. The current consumption in this mode is less than 100uA.
VCC
VCCON
VCCUVLO
UVLO
NORMAL
UVLO
Figure 1: VCC Under Voltage Lockout
13
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Multi-function 2 Pin Oscillator
The two pin oscillator is externally programmed by a resistor RT connected between pin#2 and COM and a
capacitor CT, connected from pin#3 to COM. The RT pin provides an accurate 2V reference (±2%) with a 2mA
source capability (higher the current sourced by the pin, the higher is the oscillator frequency).
In normal operation, CT is charged by a current defined by the network connected at the RT pin. The oscillator ramp
charges and discharges between the two ramp thresholds (3 and 5V). When the ramp voltage reaches 5V, it is
internally discharged by a fixed current of 2mA. The fall time for the ramp corresponds to the dead time between the
bridge devices.
At startup, a 10uA internal current source charges the oscillator capacitor at the CT pin to VEN1. At this point, the IC
is pulled out of sleep mode and the 2V reference voltage at the RT pin is enabled. The low-side device is now also
turned ON to charge the bootstrap capacitor (this sequence at startup or while exiting sleep mode ensures that the
low-side device is always switched on first to charge the bootstrap capacitor which will be ready to supply the highside floating driver). The low-side device remains ON till the CT pin voltage reaches the upper ramp threshold of 5V
(see Fig 2).
The programmable features for the oscillator are listed below• Wide frequency range:
The high-speed oscillator allows an output frequency from 50 kHz up to 500 kHz.
• Programmable dead-time:
The oscillator timing capacitor CT also programs the dead time between LO and HO.
• Programmable soft-start time:
In resonant converter applications, the output power delivered is an inverse function of frequency i.e. soft- start is
achieved by sweeping the operating frequency from an initial high value until the control loop takes over.
Additionally, the resonant tank has a non-linear frequency dependence that makes the converter’s power transfer
capability change little when the frequency is away from resonance and change very quickly as frequency
approaches the resonant tank frequency.
An R-C series circuit (CSS + RSS) connected between the RT pin and COM programs the soft-start time for the
converter. Initially, the capacitor CSS is totally discharged, so that the series resistor RSS is effectively in parallel to
Rfmin and the resulting initial frequency is determined by RSS and RT only (the optocoupler’s phototransistor is cut
off). During this frequency sweep, the operating frequency will decay following the exponential charge of CSS, that
is, initially it will change relatively quickly but the rate of change will get slower. The CSS capacitor charges until its
voltage reaches 2V and, consequently, the current through RSS is reduced to zero.
The soft-start sequence is activated at normal startup and back to operation from Sleep mode.
• Programmable start-up, minimum and maximum frequency:
In resonant converter applications, it is important to operate the converter in the soft-switching region of operation.
IRS2795(1,2)(4) offers a trimmed voltage reference (±2%) at the RT pin to accurately program the converter
switching frequency range in the desired region of operation.
- The effective resistance (RSS//RT) at pin#2 during IC power up and the CT capacitor program the start-up
frequency of the converter.
- RT and CT program the minimum operating frequency.
14
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
- For closed loop systems with feedback control, a resistor Rfmax can be connected between the RT
pin and the collector of the (emitter-grounded) phototransistor. The feedback loop modulates the
current through the phototransistor and hence, the oscillator frequency for output voltage regulation.
- The converter maximum frequency is set by (Rmax//RT) and CT.
VCCON
VCC
2V
RT
5V
CT
3V
VEN1
HO
LO
UVLO
SLEEP
NORMAL
Figure 2: Typical startup waveforms with soft-start
Frequency and Dead-time Calculation
The dead time is calculated by the following equation:
t DT = (0.85CT + 40 pF ) ⋅
15
www.irf.com
© 2012 International Rectifier
2V
2mA
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Dead-Time vs. CT Value
2000
1800
1600
DT (ns)
1400
1200
1000
800
600
400
200
0
0
500
1000
1500
2000
CT (pF)
Figure 3: Dead-time with CT capacitor chart
The running frequency of the IRS2795(1,2)(4) is given by:
f SW =
1
2 ⋅ [ RTeq (0.85CT + 40 pF ) + t DT ]
RTeq is the total equivalent resistance at RT pin.
Or just simply select the RT value form the frequency chart shown below:
Frequency Chart
500
CT=220pF
Frequency (KHz)
450
400
CT=330pF
350
CT=470pF
300
CT=1nF
250
200
150
100
50
0
0
10
20
30
40
50
RT (KΩ)
Figure 4: Switching frequency and RT selection
The maximum duty cycle is given by:
DCMAX = 0.5 − (t DT * f )
16
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
User initiated Micro Power Sleep mode
The IC can be actively pushed into a micropower sleep mode where current consumption is less than 200uA by
pulling the CT pin below the sleep threshold VEN2, even while the IC VCC is above VCCON. This mode allows the
user to disable the resonant power converter during application standby modes in order to meet regulation
standards (Blue Angel, Energy Start, Green Power etc). This IC disabling feature can also be use to implement
other system protection features.
5V
CT
3V
VEN2
HO
LO
2V
RT
NORMAL
SLEEP
Figure 5: IC transition from normal to sleep mode by pulling down CT/SD pin
Gate Drive Capability
The gate drive output stage of the IC is capable of 0.3A peak source current and 0.9A peak sink current drive
capability. Gate drive buffer circuits can be easily driven with the GATE pin of the IC to adapt to any system power
level.
System Protection Features
IRS2795(1,2)(4) uses IR’s high-voltage technology to implement a VS sensing circuitry that monitors the current
through the low-side half bridge MOSFET for short circuit faults. By using the RDSON of the low-side MOSFET, the
need for an additional current sensing resistor is eliminated. The voltage at the VS node is sensed after a leading
edge blanking time on LO. When the sensed voltage exceeds the protection thresholds, the IC enters Current
Fault Mode (gate drive outputs are disabled and the oscillator pins are internally discharged to COM).
This protection feature is latched and the IC supply voltage must be pulled below the UVLO threshold and then
again above VCCON in order to reset the latch and restart the IC.
17
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
LO
HO
VS
ILr
VS Sensing Voltage
OCP threshold
VS Sensing is enabled when LO is high
Figure 6: VS sensing over current protection
PCB Layout Tips
Distance between high and low voltage components: It is strongly recommended to place the components tied to
the floating voltage pins (VB and VS) near the respective high voltage portions of the device.
Ground Plane: In order to minimize noise coupling, the ground plane should not be placed under or near the high
voltage floating side.
Gate Drive Loops: Current loops behave like antennas and are able to receive and transmit EM noise. In order to
reduce the EM coupling and improve the power switch turn on/off performance, the gate drive loops must be
reduced as much as possible. For the low-side driver, the return of the drive loop must be directly connected to the
COM pin of the IC and separate with signal ground (power ground and signal ground have star connection at COM
pin).
Supply Capacitor: It is recommended to place a bypass capacitor (CIN) between the VCC and COM pins. A 1μF
ceramic capacitor is suitable for most applications. This component should be placed as close as possible to the
pins in order to reduce parasitic elements.
CBS Capacitor: The CBS capacitor should be placed as close as possible to the VB and VS pins.
Routing and Placement: 1) The IC has only one COM pin for both signal return and power return, so it is strongly
recommended to route the signal ground and power ground separately and with a star connection at the COM pin.
2) The RT pin provides a current reference for the internal oscillator and needs to be kept as clean as possible to
avoid frequency jittering or duty-cycle mismatch between high-side and low-side. The components connected to this
pin must keep away from the high frequency switching loop such as the gate driver loop and the VS node. The PCB
traces connected to RT pin also need to be kept away from any switching node. 3) Connect CT capacitor directly to
COM pin, don’t share the return with any other signal ground.
18
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Layout Example:
VS node
Signal components are kept
away from switching nodes
Supply bypass capacitors
are close to IC pins.
Star connection at COM pin
Additional Documentation
Please refer to application note AN-1160 for more design details of IRS2795(1,2)(4).
Several technical documents related to the use of HVICs are also available at www.irf.com; use the Site Search
function and the document number to quickly locate them. Below is a short list of some of these documents.
AN-1160: Design of Resonant Half-Bridge converter using IRS2795(1,2) Control IC
DT97-3: Managing Transients in Control IC Driven Power Stages
19
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
12.0 V
10
VCC UVLO Thresholds
ISUPPLY (mA)
11.5 V
1
0.1
11.0 V
10.5 V
10.0 V
9.5 V
9.0 V
VCC UV+
8.5 V
0.01
5.0 V
VCC UV-
7.5 V 10.0 V 12.5 V 15.0 V 17.5 V
Supply voltage
8.0 V
-50 °C
50 °C
100 °C
150 °C
Temperature
Figure 7: Supply Current vs. Supply Voltage
Figure 8: Undervoltage Lockout vs. Temperature
ICCSTART and ISLEEP
IQCC
2.6
180.0
2.4
160.0
ISLEEP
ICCSTART
140.0
2.2
Current (uA)
IQCC Quiescent Current (mA)
0 °C
2.0
1.8
1.6
120.0
100.0
80.0
60.0
40.0
1.4
20.0
1.2
1.0
-50 °C
0.0
-50 °C
0 °C
50 °C
100 °C
Temperature
150 °C
Figure 9: Icc Quiescent Currrent vs. Temperature
20
www.irf.com
© 2012 International Rectifier
0 °C
50 °C
100 °C
Temperature
150 °C
Figure 10: Startup Current and Sleep Current vs.
Temperature
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Icc @46KHz, CLOAD=1nF
9.0 V
4.0
3.8
VBS UVLO Thresholds
ICC Supply Current (mA)
3.6
3.4
3.2
3.0
2.8
2.6
8.5 V
8.0 V
7.5 V
2.4
VBS UV+
2.2
VBS UV-
2.0
-50 °C
0 °C
50 °C
100 °C
Temperature
7.0 V
-50 °C
150 °C
Figure 11: Icc Supply Currrent @1nF Load vs.
Temperature
150 °C
Dead Time @ CT=200pF
Ibs @46KHz, CLOAD=1nF
230.0
1.03
225.0
1.02
Dead Time (ns)
Ibs Supply Current (mA)
50 °C
100 °C
Temperature
Figure 12: VBS Undervoltage Lockout vs.
Temperature
1.04
1.01
1.00
0.99
220.0
215.0
210.0
205.0
0.98
0.97
-50 °C
0 °C
50 °C
100 °C
Temperature
150 °C
Figure 13: Ibs Currrent @1nF Load vs.
Temperature
21
0 °C
www.irf.com
© 2012 International Rectifier
200.0
-50 °C
0 °C
50 °C
100 °C
Temperature
150 °C
Figure 14: Dead-Time vs Temperature
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Frequency @ CT=200pF, RT=50.5KΩ
Frequency @ CT=200pF, RT=7.32KΩ
49.0
297
Switching Frequency (KHz)
Switching Frequency (KHz)
48.5
48.0
47.5
47.0
46.5
46.0
45.5
45.0
44.5
44.0
-50 °C
0 °C
50 °C
100 °C
Temperature
285
281
277
273
0 °C
100 °C
50 °C
Temperature
150 °C
Figure 16: Switching Frequency vs. Temperature
IRS2795(1,2) -Vs Spike SOA
95 ns
85 ns
80
75 ns
70
65 ns
60
Voltage (V)
Gate Tr and Tf @ 1nF Load
289
269
-50 °C
150 °C
Figure 15: Switching Frequency vs. Temperature
293
55 ns
45 ns
Tr_HO
Tr_LO
Tf_HO
Tf_LO
35 ns
Failure Voltage
50
40
30
20
25 ns
10
15 ns
0
1E-7 2E-7 3E-7 4E-7 5E-7 6E-7 7E-7 8E-7 9E-7 1E-6
5 ns
-50 °C
0 °C
50 °C
100 °C
150 °C
Pulse Width (s)
Temperature
Figure 17: Gate Output Tr and Tf time @ 1nF
Load vs. Temperature
22
www.irf.com
© 2012 International Rectifier
Figure 18: VS Negative Transient Safety
Operation Area
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Package Details: SOIC8N
23
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Package Details: SOIC14N
24
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Tape and Reel Details: SOIC8N
LOADED TAPE FEED DIRECTION
A
B
H
D
F
C
NOTE : CONTROLLING
DIMENSION IN MM
E
G
CARRIER TAPE DIMENSION FOR 8SOICN
Metric
Imperial
Code
Min
Max
Min
Max
A
7.90
8.10
0.311
0.318
B
3.90
4.10
0.153
0.161
C
11.70
12.30
0.46
0.484
D
5.45
5.55
0.214
0.218
E
6.30
6.50
0.248
0.255
F
5.10
5.30
0.200
0.208
G
1.50
n/a
0.059
n/a
H
1.50
1.60
0.059
0.062
F
D
C
B
A
E
G
H
REEL DIMENSIONS FOR 8SOICN
Metric
Code
Min
Max
A
329.60
330.25
B
20.95
21.45
C
12.80
13.20
D
1.95
2.45
E
98.00
102.00
F
n/a
18.40
G
14.50
17.10
H
12.40
14.40
25
www.irf.com
Imperial
Min
Max
12.976
13.001
0.824
0.844
0.503
0.519
0.767
0.096
3.858
4.015
n/a
0.724
0.570
0.673
0.488
0.566
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Tape and Reel Details: SOIC14N
LOADED TAPE FEED DIRECTION
A
B
H
D
F
C
NOTE : CONTROLLING
DIMENSION IN MM
E
G
CARRIER TAPE DIMENSION FOR 14SOICN
Metric
Imperial
Code
Min
Max
Min
Max
A
7.90
8.10
0.311
0.318
B
3.90
4.10
0.153
0.161
C
15.70
16.30
0.618
0.641
D
7.40
7.60
0.291
0.299
E
6.40
6.60
0.252
0.260
F
9.40
9.60
0.370
0.378
G
1.50
n/a
0.059
n/a
H
1.50
1.60
0.059
0.062
F
D
C
B
A
E
G
H
REEL DIMENSIONS FOR 14SOICN
Metric
Imperial
Code
Min
Max
Min
Max
A
329.60
330.25
12.976
13.001
B
20.95
21.45
0.824
0.844
C
12.80
13.20
0.503
0.519
D
1.95
2.45
0.767
0.096
E
98.00
102.00
3.858
4.015
F
n/a
22.40
n/a
0.881
G
18.50
21.10
0.728
0.830
H
16.40
18.40
0.645
0.724
26
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Part Marking Information
SOIC8
Part number
Sxxxxx
Date code
YWW ?
Pin 1
Identifier
IR logo
? XXXX
?
MARKING CODE
P
Lead Free Released
Lot Code
(Prod mode –
4 digit SPN code)
Assembly site code
Per SCOP 200-002
Non-Lead Free Released
SOIC14
Part number
IRSxxxxx
Date code
YWW ?
Pin 1
Identifier
? XXXX
?
MARKING CODE
P
Lead Free Released
Non-Lead Free Released
27
www.irf.com
IR logo
© 2012 International Rectifier
Lot Code
(Prod mode –
4 digit SPN code)
Assembly site code
Per SCOP 200-002
th
November 8 , 2012
IRS27951S
IRS27952(4)S
Qualification Information†
††
Qualification Level
Moisture Sensitivity Level
Machine Model
ESD
Human Body Model
IC Latch-Up Test
RoHS Compliant
Industrial
Comments: This family of ICs has passed JEDEC’s
Industrial qualification. IR’s Consumer qualification level is
granted by extension of the higher Industrial level.
†††
MSL2 260°C
SOIC8N
(per IPC/JEDEC J-STD-020C)
†††
MSL2 260°C
SOIC14N
(per IPC/JEDEC J-STD-020)
Class B
(per JEDEC standard EIA/JESD22-A115-A)
Class 2
(per EIA/JEDEC standard JESD22-A114-B)
Class I, Level A
(per JESD78A)
Yes
†
††
Qualification standards can be found at International Rectifier’s web site http://www.irf.com/
Higher qualification ratings may be available should the user have such requirements. Please contact your
International Rectifier sales representative for further information.
††† Higher MSL ratings may be available for the specific package types listed here. Please contact your
International Rectifier sales representative for further information.
The information provided in this document is believed to be accurate and reliable. However, International Rectifier assumes no responsibility
for the consequences of the use of this information. International Rectifier assumes no responsibility for any infringement of patents or of other
rights of third parties which may result from the use of this information. No license is granted by implication or otherwise under any patent or
patent rights of International Rectifier. The specifications mentioned in this document are subject to change without notice. This document
supersedes and replaces all information previously supplied.
For technical support, please contact IR’s Technical Assistance Center
http://www.irf.com/technical-info/
WORLD HEADQUARTERS:
233 Kansas St., El Segundo, California 90245
Tel: (310) 252-7105
28
www.irf.com
© 2012 International Rectifier
th
November 8 , 2012
Similar pages