IR38265M [INFINEON]

OptiMOS™ IPOL DC-DC转换器,单输入电压,30A降压稳压器,配备PVID;
IR38265M
型号: IR38265M
厂家: Infineon    Infineon
描述:

OptiMOS™ IPOL DC-DC转换器,单输入电压,30A降压稳压器,配备PVID

DC-DC转换器 稳压器
文件: 总55页 (文件大小:2976K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
DCDC Converter  
OptiMOSIPOL  
IR38265  
Single-input Voltage, 30A Buck  
Regulators with PVID  
FEATURES  
DESCRIPTION  
Internal LDO allows single 16V operation  
Output Voltage Range: 0.5V to 0.875*PVin  
0.5% accurate Reference Voltage  
Enhanced line/load regulation with Feedforward  
Frequency programmable by I2C up to 1.5 MHz  
Enable input with Voltage Monitoring Capability  
This family of OPTIMOS IPOL devices offers easy-to-use,  
fully integrated and highly efficient DC/DC regulators with  
PVID and I2C interface. The on-chip PWM controller and co-  
packaged low duty cycle optimized MOSFETs make these  
devices a space-efficient solution, providing accurate power  
delivery for low output voltage and high current  
Remote Sense Amplifier with True Differential  
Voltage Sensing  
applications that require a parallel VID interface.  
3 pins (PVID) to program output voltage  
These versatile devices offer programmability of switching  
frequency, output voltage, and fault/warning thresholds  
and fault responses while operating over a wide input  
range. Thus, they offer flexibility as well as system level  
security in event of fault conditions.  
Fast mode I2C interface for programming,  
sequencing and margining output voltage, and for  
monitoring input voltage, output voltage, output  
current and temperature.  
I2C configurable fault thresholds for input UVLO,  
output OVP, OCP and thermal shutdown.  
Thermally compensated pulse-by-pulse current  
limit and Hiccup Mode Over Current Protection  
Dedicated output voltage sensing for power good  
indication and overvoltage protection which  
remains active even when Enable is low.  
The switching frequency is programmable from 150 kHz to  
1.5 MHz for an optimum solution.  
The on-chip sensors and ADC along with the PVID and I2C  
interfaces make it easy to monitor and report input voltage,  
output voltage, output current and temperature.  
Enhanced Pre-Bias Start up  
Integrated MOSFET drivers and Bootstrap diode  
Operating junction temp: -40oC<Tj<125oC  
Thermal Shut Down  
Post Package trimmed rising edge dead-time  
I2C Programmable Power Good Output  
Small Size 5mmx7mm PQFN  
Pb-Free (RoHS Compliant)  
External resistor allows setting up to 16 PMBus  
addresses  
APPLICATIONS  
Intel® VR13 and VR12.5 based systems  
Servers and High End Desktop CPU VRs for non-  
core applications  
Telecom and storage applications  
BASIC APPLICATION  
For applications in which Pvin>14V, a 1 ohm resistor is required in series with the boot capacitor.  
5.5V <Vin<16V  
Optional placeholder for boot resistor.  
Default should be 0 ohm  
For PVin >14V, a 1 ohm resistor is  
required  
P1V8  
PVin  
Enable Vin  
Boot  
Vo  
Vcc/  
LDO_out  
SW  
Vsns  
RS+  
PGood  
PGood  
RS-  
VIDSEL0  
VIDSEL1  
RSo  
Fb  
3 bit  
PVID  
VIDSEL2  
ADDR  
Comp  
LGnd  
PGnd  
Placeholder  
for capacitor  
Figure 1: Typical application circuit  
1
Rev 3.5  
Jun 7, 2019  
IR38265  
PIN DIAGRAM  
Figure 2: IR38265 Package Top View  
5mm X 7mm PQFN  
ORDERING INFORMATION  
Tape and Reel  
Description  
Package  
Qty  
Part Number  
PQFN  
4000  
IR38265MTRPbF  
30A Buck Regulator with PVID and I2C for PVNN  
2
Rev 3.5  
Jun 7, 2019  
IR38265  
FUNCTIONAL BLOCK DIAGRAM  
VCC  
Vin  
P1V8  
LDO  
VLDOref  
LDO  
LGND  
COMP  
-
OT_Fault  
+
UVcc  
OC_Fault  
BOOT  
PVIN  
VCC  
UVcc  
FAULT  
CONTROL  
UVEN  
Fault  
Fault  
VDAC2  
HDrv  
+
-
E/A  
HDin  
GATE  
DRIVE  
LOGIC  
OV_Fault  
FCCM  
SW  
FB  
VCC  
LDrv  
LDin  
Enable  
PGND  
Rso  
CONTROL AND FAULT LOGIC  
RS-  
PGood  
RS+  
ISense  
TMON  
Current Sense  
SDA  
SCL  
SVID Interface, SMBus  
Interface,  
Logic, Command and Status registers  
Temperature  
Sense  
Vcc  
ADDR  
Vsns  
VIDSEL2  
VIDSEL0  
VIDSEL1  
Figure 3: Simplified Block Diagram for IR38265  
3
Rev 3.5  
Jun 7, 2019  
IR38265  
PIN DESCRIPTIONS  
PIN #  
PIN NAME  
PIN DESCRIPTION  
1
PVIN  
Input voltage for power stage. Bypass capacitors between PVin and PGND should be  
connected very close to this pin and PGND. Typical applications use four 22 uF input  
capacitors and a low ESR, low ESL 0.1uF decoupling capacitor in a 0603/0402 case size. A  
3.3nF capacitor may also be used in parallel with these input capacitors to reduce ringing on  
the Sw node.  
2
Boot  
Supply voltage for high side driver. A 0.1uF capacitor should be connected from this pin to  
the Sw pin. It is recommended to provide a placement for a 0 ohm resistor in series with the  
capacitor. For applications in which PVin>14V, a 1 ohm resistor is required in series with  
boot capacitor.  
3
4
ENABLE  
ADDR  
Enable pin to turn on and off the IC.  
A resistor should be connected from this pin to LGnd to set the I2C address offset for the  
device. It is recommended to provide a placement for a 10 nF capacitor in parallel with the  
offset resistor.  
5
6
Vsns  
FB  
Sense pin for OVP and PGood. Typically connected to a local Vout capacitor at the output of  
the inductor.  
Inverting input to the error amplifier. This pin is connected directly to the output of the  
regulator or to the output of the remote sense amplifier, via resistor divider to set the output  
voltage and provide feedback to the error amplifier.  
7
8
COMP  
RSo  
Output of error amplifier. An external resistor and capacitor network is typically connected  
from this pin to FB to provide loop compensation.  
Remote Sense Amplifier Output. When the remote sense amplifier is used, this is connected  
to the feedback compensation network.  
9
RS-  
RS+  
Remote Sense Amplifier input. Connect to ground at the load.  
Remote Sense Amplifier input. Connect to output at the load.  
10  
11  
PGood  
Power Good status pin. Output is open drain. Connect a pull up resistor from this pin to VCC.  
If the power good voltage before VCC UVLO needs to be limited to < 500 mV, use a 49.9K  
pullup, otherwise a 4.99K pullup will suffice.  
12,25  
PGND  
Power ground. This pin should be connected to the system’s power ground plane. Bypass  
capacitors between PVin and PGND should be connected very close to PVIN pin (pin 1) and  
this pin.  
13  
14  
LGND  
Signal ground for internal reference and control circuitry. This should be connected to the  
PGnd plane at a quiet location using a single point connection.  
VIDSEL0  
Used to select VID voltage registers. This is the LSB of the 3 bit PVID code that is internally  
decoded to select the register containing the target voltage. Only connect to Vcc via a  
4.99KΩ resistor and do not use a direct connection. Do not exceed 6V.  
15  
16  
VIDSEL1  
VIDSEL2  
Used to select VID voltage registers. Only connect to Vcc via a 4.99KΩ resistor and do not  
use a direct connection. Do not exceed 6V.  
Used to select VID voltage registers. This is the MSB of the 3 bit PVID code that is internally  
decoded to select the register containing the target voltage. Only connect to Vcc via a  
4.99KΩ resistor and do not use a direct connection. Do not exceed 6V.  
17  
18  
NC  
NC  
SDA  
I2C data serial input/output line. This should be pulled up to 3.3V-5V with a 1K-5K resistor  
4
Rev 3.5  
Jun 7, 2019  
IR38265  
PIN #  
PIN NAME  
PIN DESCRIPTION  
19  
20  
SCL  
I2C clock line. This should be pulled up to 3.3V-5V with a 1K-5K resistor  
P1V8  
This is the supply for the digital circuits; bypass with a 10uF capacitor to PGnd. A 2.2uF  
capacitor is valid however a 10uF capacitor is recommended.  
21  
22  
Vin  
Input Voltage for LDO. A 1 uF capacitor is placed from this pin to PGnd. If the internal bias  
LDO is used, tie this pin to PVin. If an external bias voltage (typically 5V) is available for Vcc,  
tie the Vin pin to Vcc.  
VCC  
Bias Voltage for IC and driver section, output of LDO. Add 10 uF bypass cap from this pin to  
PGnd.  
23,26  
24  
NC  
NC  
SW  
Switch node. This pin is connected to the output inductor.  
5
Rev 3.5  
Jun 7, 2019  
IR38265  
ABSOLUTE MAXIMUM RATINGS  
Stresses beyond these listed under “Absolute Maximum Ratings” may cause permanent damage to the device.  
These are stress ratings only and functional operation of the device at these or any other conditions beyond those  
indicated in the operational sections of the specifications are not implied.  
PVin, Vin  
-0.3V to 25V  
VCC  
-0.3V to 6V  
P1V8  
-0.3V to 2 V  
SW  
-0.3V to 25V (DC), -4V to 25V (AC, 100ns)  
-0.3V to 31V  
BOOT  
BOOT to SW  
-0.3V to 6V (DC) (Note 1), -0.3V to 6.5V (AC, 100ns)  
-0.3V to 6V (Note 1)  
PGD, other Input/output pins  
PGND to GND, RS- to GND  
-0.3V to + 0.3V  
THERMAL INFORMATION  
Junction to ambient thermal resistance θJA  
Junction to board thermal resistance θJB  
Junction to case top thermal resistance θJC(top)  
11.1 C/W (Note 2)  
4.16 C/W (Note 3)  
18.9 C/W (Note 4)  
Junction to case top thermal parameter ΨJT (top)  
0.32 C/W (Note 2)  
-55°C to 150°C  
Storage Temperature Range  
Junction Temperature Range  
-40°C to 150°C  
(Voltages referenced to GND unless otherwise specified)  
Note 1: Must not exceed 6V.  
Note 2: Value obtained via thermal simulation under natural convention on a PVNN, IR38263 demo board.  
10 layer, 7” x 5.5”x0.072” PCB with 1.5 oz copper at the top and bottom layer. Inner layers 2, 3, 8 and 9 have  
1 oz copper and layers 4,5,6,7 have 2 oz copper. Ta = 25C was used for the simulation.  
Note 3: PCB from note 2 and package is considered in thermal simulation with Ta=25 C. Pin 12 is considered.  
Note 4: Only package is considered. Simulation is used with a cold plate that fixes top of package at Ta=25 C.  
6
Rev 3.5  
Jun 7, 2019  
IR38265  
ELECTRICAL SPECIFICATIONS  
RECOMMENDED OPERATING CONDITIONS  
SYMBOL  
DEFINITION  
MIN  
MAX  
UNITS  
PVin  
Input Bus Voltage  
1.5  
5.3  
4.5  
4.5  
0.5  
0
16*  
16  
V
Vin  
LDO supply voltage  
LDO output/Bias supply voltage  
High Side driver gate voltage  
Output Voltage  
VCC  
5.5  
Boot to SW  
5.5  
VO  
IO  
0.875*PVin  
30  
Output Current  
A
Fs  
TJ  
Switching Frequency  
Junction Temperature  
150  
-40  
1500  
125  
kHz  
°C  
* SW Node must not exceed 25V  
PARAMETER  
MOSFET Rds(on)  
SYMBOL  
CONDITIONS  
MIN  
TYP  
MAX  
UNIT  
Rds(on)_Top  
Rds(on)_Bot  
Top Switch  
VBoot VSW = 5V, ID = 30A, Tj  
= 25°C  
2.2  
mΩ  
Bottom Switch  
Vcc =5V, ID = 30A, Tj = 25°C  
0.78  
Reference Voltage  
1.25V<VFB<2.555V  
VOUT_SCALE_LOOP=1;  
-1  
+1  
%
Accuracy  
00C<Tj<850C  
0.75V<VFB<1.25V  
VOUT_SCALE_LOOP=1;  
-0.75  
-0.5  
+0.75  
+0.5  
0.45V<VFB<0.75V  
%
%
VOUT_SCALE_LOOP=1;  
1.25V<VFB<2.555V  
VOUT_SCALE_LOOP=1;  
-1.6  
-1.0  
-2.0  
+1.6  
+1.0  
+2.0  
Accuracy  
-400C<Tj<1250C  
0.75V<VFB<1.25V  
VOUT_SCALE_LOOP=1;  
%
%
0.45V<VFB<0.75V  
VOUT_SCALE_LOOP=1;  
Supply Current  
PVin range (using  
external Vcc=5V)  
1.5-  
16  
V
V
Vin range (using internal  
LDO)  
Fsw=600kHz  
5.3-  
16  
7
Rev 3.5  
Jun 7, 2019  
IR38265  
PARAMETER  
SYMBOL  
CONDITIONS  
Fsw=1.5MHz  
MIN  
TYP  
MAX  
UNIT  
5.5-  
16  
Vin range (when  
Vin=Vcc)  
4.5  
5.0  
2.7  
39  
5.5  
4
V
Iin(Standby)  
Vin Supply Current  
(Standby) (internal Vcc)  
Enable low, No Switching,  
Vin=16V, low power mode  
enabled  
mA  
mA  
mA  
mA  
Iin(Dyn)  
Vin Supply Current  
(Dyn)(internal Vcc)  
Enable high, Fs = 600kHz,  
Vin=16V  
50  
5
Icc(Standby)  
VCC Supply Current  
(Standby)(external Vcc)  
Enable low, No Switching,  
Vcc=5.5V, low power mode  
enabled  
2.7  
39  
Icc(Dyn)  
VCC Supply Current  
(Dyn)(external Vcc)  
Enable high, Fs = 600kHz,  
Vcc=5.5V  
50  
Under Voltage Lockout  
VCC Start Threshold  
VCC Stop Threshold  
VCC_UVLO_Start  
VCC_UVLO_Stop  
Enable_UVLO_Start  
VCC Rising Trip Level  
VCC Falling Trip Level  
Supply ramping up  
4.0  
3.7  
4.2  
3.9  
4.4  
4.1  
V
Enable Start –  
Threshold  
0.55  
0.35  
0.6  
0.4  
0.65  
V
Enable_UVLO_Stop  
Ien  
Enable Stop –  
Threshold  
Supply ramping down  
Enable=5.5V  
0.45  
1
Enable leakage current  
Oscillator  
µA  
Vramp  
Ramp Amplitude  
PVin=5V, D=Dmax, Note 2  
PVin=12V, D=Dmax, Note 2  
PVin=16V,D=Dmax, Note 2  
Note 2  
0.71  
1.84  
2.46  
0.22  
35  
Vp-p  
Ramp (os)  
Dmin (ctrl)  
Ramp Offset  
Min Pulse Width  
Fixed Off Time  
Max Duty Cycle  
Error Amplifier  
Input Bias Current  
Sink Current  
V
Note 2  
50  
150  
89  
ns  
ns  
%
Note 2 Fs=1.5MHz  
Fs=400kHz  
100  
87.5  
Dmax  
86  
IFb(E/A)  
Isink(E/A)  
Isource(E/A)  
SR  
-0.5  
0.6  
8
+0.5  
1.8  
25  
µA  
mA  
mA  
V/µs  
MHz  
dB  
1.1  
13  
Source Current  
Slew Rate  
Note 2  
Note 2  
Note 2  
7
12  
20  
GBWP  
Gain-Bandwidth Product  
DC Gain  
20  
100  
2.8  
30  
40  
Gain  
110  
3.9  
120  
4.3  
100  
Vmax(E/A)  
Vmin(E/A)  
Maximum Voltage  
Minimum Voltage  
V
mV  
8
Rev 3.5  
Jun 7, 2019  
IR38265  
PARAMETER  
SYMBOL  
CONDITIONS  
MIN  
TYP  
MAX  
UNIT  
Remote Sense Differential Amplifier  
BW_RS  
Unity Gain Bandwidth  
Note 2  
Note 2  
3
6.4  
MHz  
dB  
Gain_RS  
DC Gain  
110  
0.5V<RS+<2.555V, 4kOhm  
load  
270C<Tj<850C  
-1.6  
-3  
0
1.6  
3
Offset_RS  
Offset Voltage  
mV  
0.5V<RS+<2.555V, 4kOhm  
load  
-400C<Tj<1250C  
Isource_RS  
Isink_RS  
Slew_RS  
Rin_RS+  
Rin_RS-  
Source Current  
Sink Current  
V_RSO=1.5V, V_RSP=4V  
11  
0.4  
2
16  
2
mA  
mA  
1
4
Slew Rate  
Note 2, Cload = 100pF  
8
V/µs  
Kohm  
Kohm  
V
RS+ input impedance  
RS- input impedance  
Maximum Voltage  
Minimum Voltage  
Bootstrap Diode  
Forward Voltage  
Switch Node  
36  
36  
0.5  
55  
55  
1
74  
74  
1.5  
20  
Note 2  
Vmax_RS  
Min_RS  
V(VCC) V(RS+)  
4
mV  
I(Boot) = 40mA  
150  
300  
18  
450  
1
mV  
µA  
lsw  
SW Leakage Current  
SW = 0V, Enable = 0V  
SW=0; Enable= 2V  
Isw_En  
Internal Regulator (VCC/LDO)  
VCC  
Output Voltage  
Vin(min) = 5.5V, Io=0mA,  
Cload = 10uF  
4.8  
4.5  
5.15  
4.99  
5.4  
5.2  
0.7  
V
Vin(min) = 5.5V, Io=70mA,  
Cload = 10uF  
VCC_drop  
Ishort  
VCC dropout  
Io=0-70mA, Cload = 10uF,  
Vin=5.1V  
V
Short Circuit Current  
110  
mA  
Internal Regulator (P1V8)  
P1V8  
Output Voltage  
Vin(min) = 4.5V, Io = 0‐  
1mA, Cload = 2.2uF  
1.8V Rising Trip Level  
1.795  
1.83  
1.905  
V
P1V8_UVLO_Start  
P1V8_UVLO_Stop  
1.8V UVLO Start  
1.8V UVLO Stop  
1.66  
1.59  
1.72  
1.63  
1.78  
1.68  
V
V
1.8V Falling Trip Level  
Adaptive On time Mode  
ZC_Vth  
Zero-crossing  
comparator threshold  
-4  
-1  
2
mV  
s
ZC_Tdly  
Zero-crossing  
comparator delay  
8/Fs  
9
Rev 3.5  
Jun 7, 2019  
IR38265  
PARAMETER  
SYMBOL  
CONDITIONS  
FAULTS  
MIN  
TYP  
MAX  
UNIT  
Power Good  
TPDLY  
Power Good High  
Threshold Rising Delay  
Vsns rising, Vsns >  
Power_Good_High  
0
ms  
VPG_low_Dly  
PG (voltage)  
Power Good Low  
Threshold Falling delay  
Vsns falling, Vsns <  
Power_Good_Low  
150  
175  
200  
0.5  
µs  
V
PGood Voltage Low  
IPGood = -5mA  
Over Voltage Protection (OVP)  
OVP (trip)  
OVP Trip Threshold  
Vsns rising,  
VOUT_SCALE_LOOP=1,  
Vout=0.5V  
0.60  
5
0.57  
20  
0.63  
40  
V
OVP (hyst)  
OVP comparator  
Hysteresis  
Vsns falling,  
VOUT_SCALE_LOOP=1,  
Vout=0.5V  
30  
mV  
ns  
OVP (delay)  
OVP Fault Prop Delay  
Vsns rising, Vsns-  
OVP(trip)>200 mV  
200  
Over-Current Protection  
ITRIP  
OC limit=40, VCC = 5.05V,  
Tj=250C  
36  
40  
16  
44  
A
A
OC Trip Current  
OC limit=16A, VCC = 5.05V,  
Tj=250C  
12.5  
19.5  
OCSET(temp)  
Tblk_Hiccup  
OCset Current  
Temperature coefficient  
-400C to 1250C, VCC=5.05V,  
Note 2  
5900  
20  
ppm/°C  
ms  
Hiccup blanking time  
Thermal Shutdown  
Thermal Shutdown  
Hysteresis  
Note 2  
Note 2  
Note 2  
145  
25  
°C  
°C  
Input Over-Voltage Protection  
PVinOV  
PVin overvoltage  
threshold  
22  
23.7  
2.4  
25  
V
V
PVin ov hyst  
PVin overvoltage  
Hysteresis  
MONITORING AND REPORTING  
Bus Speed1  
100  
78  
400  
kHz  
Hz  
Iout & Vout filter  
31.2  
5
Iout & Vout Update rate  
Vin & Temperature filter  
kHz  
Hz  
78  
Vin  
update rate  
&
Temperature  
31.2  
5
kHz  
10  
Rev 3.5  
Jun 7, 2019  
IR38265  
PARAMETER  
SYMBOL  
CONDITIONS  
MIN  
TYP  
MAX  
UNIT  
Output Voltage Reporting  
Resolution  
NVout  
1/256  
0
Note 2  
V
V
Vomon_low  
Vomon_high  
Lowest reported Vout  
Highest reported Vout  
Vsns=0V  
VOUT_SCALE_LOOP=1,  
Vsns=3.3V  
3.3  
6.6  
V
V
V
V
VOUT_SCALE_LOOP=0.5,  
Vsns=3.3V  
VOUT_SCALE_LOOP=0.25,  
Vsns=3.3V  
13.2  
26.4  
VOUT_SCALE_LOOP=0.125  
, Vsns=3.3V  
Vout reporting accuracy  
00C to 850C, 4.5V<Vcc<5.5V,  
1V<Vsns1.5V  
VOUT_SCALE_LOOP=1  
+/-  
0.6  
00C to 850C, 4.5V<Vcc<5.5V,  
Vsns> 1.5V  
+/-1  
VOUT_SCALE_LOOP=1  
%
00C to 1250C,  
4.5V<Vcc<5.5V, Vsns>0.9V  
VOUT_SCALE_LOOP=1  
+/-  
1.5  
00C to 1250C,  
4.5V<Vcc<5.5V,  
0.5V<Vsns<0.9V  
VOUT_SCALE_LOOP=1  
+/-3  
Iout Reporting  
NIout  
Resolution  
Note 2  
0.06  
25  
A
A
Iout_dig  
I
Iout (digital) monitoring  
Range  
0
40  
00C to 1250C,  
4.5V<Vcc<5.5V, 5A < Iout  
<30A  
Iout_dig Accuracy  
+/-5  
1
%
Temperature Reporting  
NTmon  
Resolution  
Note 2  
Note 2  
°C  
°C  
Tmon_dig  
Temperature Monitoring  
Range  
-40  
150  
Thermal shutdown  
hysteresis  
25  
°C  
Input Voltage Reporting  
Resolution  
NPVin  
Note 2  
1/32  
V
V
PMBVinmon  
Monitoring Range  
Monitoring accuracy  
0
21  
00C to 850C, 4.5V<Vcc<5.5V,  
-1.5  
1.5  
11  
Rev 3.5  
Jun 7, 2019  
IR38265  
PARAMETER  
SYMBOL  
CONDITIONS  
PVin>10V  
MIN  
TYP  
MAX  
UNIT  
%
-400C to 1250C,  
4.5V<Vcc<5.5V, PVin>14V  
-1.5  
-4  
1.5  
4
-400C to 1250C,  
4.5V<Vcc<5.5V,  
7V<PVin<14V  
I2C Interface Timing Specifications  
FSMB  
I2C Operating frequency  
400  
kHz  
µs  
TBUF  
Bus Free time between  
Start and Stop condition  
1.3  
0.6  
THD:STA  
Hold time after  
(Repeated) Start  
Condition. After this  
period, the first clock is  
generated.  
µs  
TSU:STA  
Repeated start condition  
setup time  
0.6  
0.6  
µs  
µs  
TSU:STO  
Stop condition setup  
time  
Data Rising Threshold  
Data Falling Threshold  
Clock Rising Threshold  
Clock Falling Threshold  
1.339  
1.048  
1.339  
1.048  
1.766  
1.495  
1.766  
1.499  
V
V
V
V
Data Rising Threshold  
LVT  
0.7  
0.45  
0.7  
0.9  
0.65  
0.9  
V
V
V
V
Data Falling Threshold  
LVT  
Clock Rising Threshold  
LVT  
Clock Falling Threshold  
LVT  
0.45  
0.65  
900  
THD:DAT  
Data Hold Time  
300  
100  
ns  
ns  
TSU:DAT  
Data Setup Time  
Data pulldown  
resistance  
8
11  
16  
35  
TTIMEOUT  
Clock low time out  
25  
1.3  
0.6  
ms  
µs  
µs  
TLOW  
Clock low period  
THIGH  
Clock High Period  
50  
Digital Inputs Low Vth Type 2 (VIDSELx)  
-
-
Input High Voltage  
0.65  
V
12  
Rev 3.5  
Jun 7, 2019  
IR38265  
PARAMETER  
SYMBOL  
CONDITIONS  
MIN  
TYP  
MAX  
UNIT  
Input Low Voltage  
Hysteresis  
-
-
-
-
95  
-
0.45  
-
V
mV  
µA  
Input Leakage Current  
Vpad = 0 to 2V  
±1  
Notes  
2. Guaranteed by design but not tested in production  
3. Guaranteed by statistical correlation, but not tested in production  
13  
Rev 3.5  
Jun 7, 2019  
IR38265  
TYPICAL APPLICATION DIAGRAMS  
5.5V <Vin<16V  
Optional placeholder for boot resistor.  
Default should be 0 ohm  
For PVin >14V, a 1 ohm resistor is  
required  
P1V8  
PVin  
Enable  
Vin  
Boot  
SW  
Vo  
Vcc/  
LDO_out  
Vsns  
RS+  
PGood  
PGood  
RS-  
VIDSEL0  
VIDSEL1  
RSo  
Fb  
3 bit  
PVID  
VIDSEL2  
ADDR  
Comp  
LGnd  
PGnd  
Placeholder  
for capacitor  
Figure 4: Using the internal LDO, Vo < 2.555V  
For applications in which Pvin>14V, a 1 ohm resistor is required in series with the boot capacitor.  
5.5V <Vin<16V  
Optional placeholder for boot resistor.  
Default should be 0 ohm  
Boot  
P1V8  
PVin  
Enable  
Vin  
Vo  
Vcc/  
LDO_out  
SW  
Vsns  
RS+  
PGood  
R2  
PGood  
RS-  
VIDSEL0  
CPU  
serial  
bus  
RSo  
Fb  
Recommend R2=499 ohm  
VIDSEL1  
VIDSEL2  
Comp  
LGnd  
ADDR
PGnd  
Placeholder  
for capacitor  
Figure 5: Using the internal LDO, Vo > 2.555V  
14  
Rev 3.5  
Jun 7, 2019  
IR38265  
TYPICAL APPLICATION DIAGRAMS  
1.5V <PVin<16V  
Optional placeholder for boot resistor.  
Default should be 0 ohm  
For PVin >14V, a 1 ohm resistor is  
required  
P1V8  
PVin  
Enable  
Vin  
Boot  
Vcc=5V  
PGood  
Vo  
Vcc/  
LDO_out  
SW  
Vsns  
RS+  
PGood  
RS-  
VIDSEL0  
VIDSEL1  
VIDSEL2  
3 bit  
PVID  
RSo  
Fb  
Comp  
LGnd  
ADDR  
PGnd  
Placeholder  
for capacitor  
Figure 6: Using external Vcc, Vo<2.555V  
PVin=Vin=Vcc= 5V  
Optional placeholder for boot resistor.  
Default should be 0 ohm  
Boot  
P1V8  
PVin  
Enable  
Vin  
Vo  
Vcc/  
LDO_out  
SW  
Vsns  
RS+  
PGood  
PGood  
RS-  
VIDSEL0  
VIDSEL1  
VIDSEL2  
RSo  
Fb  
3 bit  
PVID  
Comp  
LGnd  
ADDR  
PGnd  
Placeholder  
for capacitor  
Figure 7: Single 5V application, Vo<2.555V  
15  
Rev 3.5  
Jun 7, 2019  
IR38265  
TYPICAL OPERATING CHARACTERISTICS (-40°C TO +125°C)  
16  
Rev 3.5  
Jun 7, 2019  
IR38265  
TYPICAL OPERATING CHARACTERISTICS (-40°C TO +125°C)  
17  
Rev 3.5  
Jun 7, 2019  
IR38265  
TYPICAL OPERATING CHARACTERISTICS (-40°C TO +125°C)  
18  
Rev 3.5  
Jun 7, 2019  
IR38265  
TYPICAL OPERATING CHARACTERISTICS (-40°C TO +125°C)  
19  
Rev 3.5  
Jun 7, 2019  
IR38265  
TYPICAL EFFICIENCY AND POWER LOSS CURVES  
PVin = Vin = 12V, VCC = 5V, Io=0-30A, Fs= 600kHz, Room Temperature, No Air Flow. Note that the losses of the  
inductor, input and output capacitors are also considered in the efficiency and power loss curves. The table below  
shows the indicator used for each of the output voltages in the efficiency measurement.  
VOUT (V)  
LOUT (uH)  
0.15  
P/N  
DCR (mΩ)  
0.15  
0.8  
1
HCB178380D-151 (Delta)  
HCB138380D-151 (Delta)  
HCB138380D-151 (Delta)  
HCB138380D-151 (Delta)  
HCB138380D-101 (Delta)  
FP1308R3-R32-R (Cooper)  
FP1308R3-R32-R (Cooper)  
0.15  
0.15  
0.15  
0.15  
0.32  
0.32  
0.15  
0.15  
0.15  
0.15  
0.32  
0.32  
1.2  
1.5  
1.8  
3.3  
5
20  
Rev 3.5  
Jun 7, 2019  
IR38265  
TYPICAL EFFICIENCY AND POWER LOSS CURVES  
PVin = Vin = 12V, Internal LDO, Io=0-30A, Fs= 600kHz, Room Temperature, No Air Flow. Note that the losses of the  
inductor, input and output capacitors are also considered in the efficiency and power loss curves. The table below  
shows the indicator used for each of the output voltages in the efficiency measurement.  
VOUT (V)  
LOUT (uH)  
0.15  
P/N  
DCR (mΩ)  
0.15  
0.8  
1
HCB178380D-151 (Delta)  
HCB138380D-151 (Delta)  
HCB138380D-151 (Delta)  
HCB138380D-151 (Delta)  
HCB138380D-101 (Delta)  
FP1308R3-R32-R (Cooper)  
FP1308R3-R32-R (Cooper)  
0.15  
0.15  
0.15  
0.15  
0.32  
0.32  
0.15  
0.15  
0.15  
0.15  
0.32  
0.32  
1.2  
1.5  
1.8  
3.3  
5
21  
Rev 3.5  
Jun 7, 2019  
IR38265  
TYPICAL EFFICIENCY AND POWER LOSS CURVES  
PVin = Vin = VCC = 5V, Io=0-30A, Fs= 600kHz, Room Temperature, No Air Flow. Note that the losses of the inductor,  
input and output capacitors are also considered in the efficiency and power loss curves. The table below shows the  
indicator used for each of the output voltages in the efficiency measurement.  
VOUT (V)  
LOUT (uH)  
0.1  
P/N  
DCR (mΩ)  
0.15  
0.8  
1
1.2  
1.5  
1.8  
HCB138380D-101 (Delta)  
HCB138380D-101 (Delta)  
HCB138380D-101 (Delta)  
HCB138380D-151 (Delta)  
HCB138380D-151 (Delta)  
0.1  
0.15  
0.15  
0.15  
0.15  
0.15  
0.15  
0.15  
22  
Rev 3.5  
Jun 7, 2019  
IR38265  
THERMAL DERATING CURVES  
The measurements were done on an evaluation kit demo board. The PCB is 7.0” x 5.5” x 0.072” with 10-layers,  
FR4 material and 2 oz. copper. The conditions used were, PVin = Vin = 12V, Internal LDO, Io=30A, Fs= 978kHz.  
IR38265 Thermal Derating Curves  
PVin=12V, Vout=1V, Fsw=978kHz  
31  
29  
27  
25  
23  
0 LFM  
21  
200 LFM  
400 LFM  
19  
17  
15  
25  
30  
35  
40  
45  
50  
55  
60  
65  
70  
75  
80  
85  
TAmb (˚C)  
23  
Rev 3.5  
Jun 7, 2019  
IR38265  
THEORY OF OPERATION  
DESCRIPTION  
The IR38265 is a 30A rated synchronous buck converter that supports II2C communication. This device also has  
3 pins that function as a parallel VID interface that can be used to set the output voltage to one of eight pre-  
programmed settings. They use an externally compensated fast, analog, PWM voltage mode control scheme to  
provide good noise immunity as well as fast dynamic response in a wide variety of applications. At the same time,  
the digital communication interfaces allow complete configurability of output setting and fault functions, as well as  
telemetry.  
The switching frequency is programmable from 150 kHz to 1500 kHz and provides the capability of optimizing the  
design in terms of size and performance. Recommend 500 kHz or higher frequencies.  
This device provides precisely regulated output voltages from 0.5V to 0.875*PVin programmed via two external  
resistors or through the communication interfaces. They operate with an internal bias supply (LDO), typically 5.2V.  
This allows operation with a single supply. The output of this LDO is brought out at the Vcc pin and must be  
bypassed to the system power ground with a 10 uF decoupling capacitor. The Vcc pin may also be connected to  
the Vin pin, and an external Vcc supply between 4.5V and 5.5V may be used, allowing an extended operating bus  
voltage (PVin) range from 1.5V to 16V.  
The device utilizes the on-resistance of the low side MOSFET (synchronous MOSFET) as current sense element.  
This method enhances the converter’s efficiency and reduces cost by eliminating the need for external current  
sense resistor.  
The IR38265 includes two low Rds(on) MOSFETs using Infineon’s OptiMOS technology. These are specifically  
designed for low duty cycle, high efficiency applications.  
DEVICE POWER-UP AND INITIALIZATION  
During the power-up sequence, when Vin is brought up, the internal LDO converts it to a regulated 5.2V at Vcc.  
There is another LDO which further converts this down to 1.8V to supply the internal digital circuitry. An under-  
voltage lockout circuit monitors the voltage of VCC pin and the P1V8 pin, and holds the Power-on-reset (POR)  
low until these voltages exceed their thresholds and the internal 48 MHz oscillator is stable. When the device  
comes out of reset, it initializes a multiple times programmable (MTP) memory load cycle, where the contents of  
the MTP are loaded into the working registers. Once the registers are loaded from MTP, the designer can use the  
I2C interface to re-configure the various parameters to suit the specific VR design requirements if desired,  
irrespective of the status of Enable.  
The typical default configuration utilizes the internal LDO to supply the VCC rail when PVin is brought up. For this  
configuration power conversion is enabled only when the Enable pin voltage exceeds its under-voltage threshold,  
the PVin bus voltage exceeds its under-voltage threshold, the contents of the MTP have been fully loaded into the  
working registers and the device address has been read. The initialization sequence is shown in Figure 8.  
Another common default configuration uses an external power supply for the VCC rail. While in this configuration  
it is recommended to ensure the VCC rail reaches its target voltage prior the enable signal goes high.  
Additional options are available to enable the device power conversion through software and these options may  
be configured to override the default by using the I2C interface.  
24  
Rev 3.5  
Jun 7, 2019  
IR38265  
PVIN=VIN  
VCC  
P1V8  
UVOK  
clkrdy  
POR  
Initialization  
done  
Enable  
Vout  
Figure 8: Initialization sequence showing PVin, Vin, Vcc, 1.8V, Enable and Vout signals as well as the internal logic  
signals  
I2C COMMUNICATION  
The IR38265 has two 7-bit registers that are used to set the base I2C address, as shown below in Table 1.  
Table 1: Registers used to set device base address  
Register  
Description  
I2C_address[6:0]  
The chip I2C address. An  
address of 0 will disable  
I2C communication.  
In addition, a resistor may be connected between the ADDR and LGND pins to set an offset from the default  
preconfigured I2C address (0x10) in the MTP. Up to 16 different offsets can be set, allowing 16 devices with  
unique addresses in a single system. This offset, and hence, the device address, is read by the internal 10 bit  
ADC during the initialization sequence.  
Table 2 below provides the resistor values needed to set the 16 offsets from the base address.  
Table 2 : Address offset vs. External Resistor(RADDR  
)
ADDR Resistor  
Address Offset  
(Ohm)  
+0  
+1  
+2  
+3  
+4  
+5  
+6  
+7  
+8  
499  
1050  
1540  
2050  
2610  
3240  
3830  
4530  
5230  
25  
Rev 3.5  
Jun 7, 2019  
IR38265  
+9  
6040  
6980  
+10  
+11  
+12  
+13  
+14  
+15  
7870  
8870  
9760  
10700  
>11800  
The device will then respond to I2C commands sent to this address. There is also a register bit  
I2C_disable_addr_offset that may be set in order to instruct the device to ignore the resistor offset. If this bit is set,  
the device will always respond to commands sent to the base address.  
MODES FOR SETTING OUTPUT VOLTAGES  
The IR38265 uses the VIDSEL0, VIDSEL1 and VIDSEL2 lines to set the output voltage. The VIDSELx lines select  
an MTP register which holds a VID value that sets the output voltage. The MTP registers are programmable via  
I2C. Note that the same VID value can result in different voltages depending on which VID table, 5mV or 10mV  
has been selected. Table 3 shows how the VIDSELx lines are used to select the register containing the target  
value. It is worth noting that the VIDSEL lines may be driven with logic gates or with Open drain devices. When  
driven by open drain devices, a pullup resistor of 4.99K must be used. When driven by logic gates, a resistor of  
4.99K is required in series with the pin. The VID tables for 5mV and 10mV VID steps are shown in the tables 4  
and 5 below.  
Table 3: Mapping the VIDSEL lines to MTP registers  
VIDSEL2  
VIDSEL1  
VIDSEL0  
Selects MTP register address  
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
77h  
78h  
79h  
7Ah  
7Bh  
7Ch  
7Dh  
7Eh  
26  
Rev 3.5  
Jun 7, 2019  
IR38265  
Table 4: Intel 5mV VID table  
VID  
Voltage  
(V)  
1.52  
1.515  
1.51  
1.505  
1.5  
1.495  
1.49  
1.485  
1.48  
1.475  
1.47  
1.465  
1.46  
1.455  
1.45  
1.445  
1.44  
1.435  
1.43  
1.425  
1.42  
1.415  
1.41  
1.405  
1.4  
1.395  
1.39  
1.385  
1.38  
1.375  
1.37  
1.365  
1.36  
1.355  
1.35  
1.345  
1.34  
1.335  
1.33  
1.325  
1.32  
1.315  
1.31  
1.305  
1.3  
1.295  
1.29  
1.285  
1.28  
1.275  
1.27  
1.265  
1.26  
1.255  
1.25  
VID  
Voltage  
(V)  
1.23  
1.225  
1.22  
1.215  
1.21  
1.205  
1.2  
1.195  
1.19  
1.185  
1.18  
1.175  
1.17  
1.165  
1.16  
1.155  
1.18  
1.175  
1.17  
1.165  
1.16  
1.155  
1.15  
1.145  
1.14  
1.135  
1.13  
1.125  
1.12  
1.115  
1.11  
1.105  
1.1  
1.095  
1.09  
1.085  
1.08  
1.075  
1.07  
1.065  
1.06  
1.055  
1.05  
1.045  
1.04  
1.035  
1.03  
1.025  
1.02  
1.015  
1.01  
1.005  
1
0.995  
0.99  
VID  
Voltage  
(V)  
0.97  
0.965  
0.96  
0.955  
0.95  
0.945  
0.94  
0.935  
0.93  
0.925  
0.92  
0.915  
0.91  
0.905  
0.9  
0.895  
0.89  
0.885  
0.88  
0.875  
0.87  
0.865  
0.86  
0.855  
0.85  
0.845  
0.84  
0.835  
0.83  
0.825  
0.82  
0.815  
0.81  
0.805  
0.8  
0.795  
0.79  
0.785  
0.78  
0.775  
0.77  
0.765  
0.76  
0.755  
0.75  
0.745  
0.74  
0.735  
0.73  
0.725  
0.72  
0.715  
0.71  
0.705  
0.7  
VID  
Voltage  
(V)  
0.68  
0.675  
0.67  
0.665  
0.66  
0.655  
0.65  
0.645  
0.64  
0.635  
0.63  
0.625  
0.62  
0.615  
0.61  
0.605  
0.6  
0.685  
0.68  
0.675  
0.67  
0.665  
0.66  
0.655  
0.65  
0.645  
0.64  
0.635  
0.63  
0.625  
0.62  
0.615  
0.61  
0.605  
0.6  
0.595  
0.59  
0.585  
0.58  
0.575  
0.57  
0.565  
0.56  
0.555  
0.55  
0.545  
0.54  
0.535  
0.53  
0.525  
0.52  
0.515  
0.51  
0.505  
0.5  
VID  
Voltage  
(V)  
(Hex)  
(Hex)  
(Hex)  
(Hex)  
(Hex)  
2F  
2E  
2D  
2C  
2B  
2A  
29  
28  
27  
26  
25  
24  
23  
22  
21  
20  
1F  
1E  
1D  
1C  
1B  
1A  
19  
18  
17  
16  
15  
14  
13  
12  
11  
10  
F
FF  
FE  
FD  
FC  
FB  
FA  
F9  
F8  
F7  
F6  
F5  
F4  
F3  
F2  
F1  
F0  
EF  
EE  
ED  
EC  
EB  
EA  
E9  
E8  
E7  
E6  
E5  
E4  
E3  
E2  
E1  
E0  
DF  
DE  
DD  
DC  
DB  
DA  
D9  
D8  
D7  
D6  
D5  
D4  
D3  
D2  
D1  
D0  
CF  
CE  
CD  
CC  
CB  
CA  
C9  
C8  
C7  
C6  
C5  
C4  
C3  
C2  
C1  
C0  
BF  
BE  
BD  
BC  
BB  
BA  
B9  
B8  
B7  
B6  
BB  
BA  
B9  
B8  
B7  
B6  
B5  
B4  
B3  
B2  
B1  
B0  
AF  
AE  
AD  
AC  
AB  
AA  
A9  
A8  
A7  
A6  
A5  
A4  
A3  
A2  
A1  
A0  
9F  
9E  
9D  
9C  
9B  
9A  
99  
91  
90  
8F  
8E  
8D  
8C  
8B  
8A  
89  
88  
87  
86  
85  
84  
83  
82  
81  
80  
7F  
7E  
7D  
7C  
7B  
7A  
79  
78  
77  
76  
75  
74  
73  
72  
71  
70  
6F  
6E  
6D  
6C  
6B  
6A  
69  
68  
67  
66  
65  
64  
63  
62  
61  
60  
5F  
5E  
5D  
5C  
5B  
5A  
59  
58  
57  
56  
55  
54  
53  
52  
51  
50  
4F  
4E  
4D  
4C  
4B  
4A  
49  
48  
47  
58  
57  
56  
55  
54  
53  
52  
51  
50  
4F  
4E  
4D  
4C  
4B  
4A  
49  
48  
47  
46  
45  
44  
43  
42  
41  
40  
3F  
3E  
3D  
3C  
3B  
3A  
39  
38  
37  
36  
35  
34  
33  
32  
31  
30  
0.48  
0.475  
0.47  
0.465  
0.46  
0.455  
0.45  
0.445  
0.44  
0.435  
0.43  
0.425  
0.42  
0.415  
0.41  
0.405  
0.4  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
0
E
D
C
B
A
9
8
7
6
5
4
3
2
1
0
98  
97  
96  
95  
94  
93  
92  
1.245  
1.24  
1.235  
0.985  
0.98  
0.975  
0.695  
0.69  
0.685  
0.495  
0.49  
0.485  
27  
Rev 3.5  
Jun 7, 2019  
IR38265  
Table 4: Intel 10mV VID table  
VID  
VOLTAGE  
(V)  
VID  
VOLTAGE  
(V)  
VID  
VOLTAGE  
(V)  
VID  
VOLTAGE  
(V)  
VID  
VOLTAGE  
(V)  
(HEX)  
(HEX)  
(HEX)  
(HEX)  
(HEX)  
17  
16  
15  
14  
13  
12  
11  
10  
F
FF  
FE  
FD  
FC  
FB  
FA  
F9  
F8  
F7  
F6  
F5  
F4  
F3  
F2  
F1  
F0  
EF  
EE  
ED  
EC  
EB  
EA  
E9  
E8  
E7  
E6  
E5  
E4  
E3  
E2  
E1  
E0  
DF  
DE  
DD  
DC  
DB  
DA  
D9  
D8  
D7  
D6  
D5  
D4  
D3  
D2  
D1  
D0  
CF  
CE  
CD  
CC  
CB  
CA  
C9  
C8  
C7  
C6  
3.04  
3.03  
3.02  
3.01  
3.00  
2.99  
2.98  
2.97  
2.96  
2.95  
2.94  
2.93  
2.92  
2.91  
2.90  
2.89  
2.88  
2.87  
2.86  
2.85  
2.84  
2.83  
2.82  
2.81  
2.80  
2.79  
2.78  
2.77  
2.76  
2.75  
2.74  
2.73  
2.72  
2.71  
2.70  
2.69  
2.68  
2.67  
2.66  
2.65  
2.64  
2.63  
2.62  
2.61  
2.60  
2.59  
2.58  
2.57  
2.56  
2.55  
2.54  
2.53  
2.52  
2.51  
2.50  
2.49  
2.48  
2.47  
C5  
C4  
C3  
C2  
C1  
C0  
BF  
BE  
BD  
BC  
BB  
BA  
B9  
B8  
B7  
B6  
B5  
B4  
B3  
B2  
B1  
B0  
AF  
AE  
AD  
AC  
AB  
AA  
A9  
A8  
A7  
A6  
A5  
A4  
A3  
A2  
A1  
A0  
9F  
9E  
9D  
9C  
9B  
9A  
99  
2.46  
2.45  
2.44  
2.43  
2.42  
2.41  
2.40  
2.39  
2.38  
2.37  
2.36  
2.35  
2.34  
2.33  
2.32  
2.31  
2.30  
2.29  
2.28  
2.27  
2.26  
2.25  
2.24  
2.23  
2.22  
2.21  
2.20  
2.19  
2.18  
2.17  
2.16  
2.15  
2.14  
2.13  
2.12  
2.11  
2.10  
2.09  
2.08  
2.07  
2.06  
2.05  
2.04  
2.03  
2.02  
2.01  
2.00  
1.99  
1.98  
1.97  
1.96  
1.95  
1.94  
1.93  
1.92  
1.91  
1.90  
1.89  
8B  
8A  
89  
88  
87  
86  
85  
84  
83  
82  
81  
80  
7F  
7E  
7D  
7C  
7B  
7A  
79  
78  
77  
76  
75  
74  
73  
72  
71  
70  
6F  
6E  
6D  
6C  
6B  
6A  
69  
68  
67  
66  
65  
64  
63  
62  
61  
60  
5F  
5E  
5D  
5C  
5B  
5A  
59  
58  
57  
56  
55  
54  
53  
52  
1.88  
1.87  
1.86  
1.85  
1.84  
1.83  
1.82  
1.81  
1.80  
1.79  
1.78  
1.77  
1.76  
1.75  
1.74  
1.73  
1.72  
1.71  
1.70  
1.69  
1.68  
1.67  
1.66  
1.65  
1.64  
1.63  
1.62  
1.61  
1.60  
1.59  
1.58  
1.57  
1.56  
1.55  
1.54  
1.53  
1.52  
1.51  
1.50  
1.49  
1.48  
1.47  
1.46  
1.45  
1.44  
1.43  
1.42  
1.41  
1.40  
1.39  
1.38  
1.37  
1.36  
1.35  
1.34  
1.33  
1.32  
1.31  
51  
50  
4F  
4E  
4D  
4C  
4B  
4A  
49  
48  
47  
46  
45  
44  
43  
42  
41  
40  
3F  
3E  
3D  
3C  
3B  
3A  
39  
38  
37  
36  
35  
34  
33  
32  
31  
30  
2F  
2E  
2D  
2C  
2B  
2A  
29  
28  
27  
26  
25  
24  
23  
22  
21  
20  
1F  
1E  
1D  
1C  
1B  
1A  
19  
18  
1.30  
1.29  
1.28  
1.27  
1.26  
1.25  
1.24  
1.23  
1.22  
1.21  
1.20  
1.19  
1.18  
1.17  
1.16  
1.15  
1.14  
1.13  
1.12  
1.11  
1.10  
1.09  
1.08  
1.07  
1.06  
1.05  
1.04  
1.03  
1.02  
1.01  
1.00  
0.99  
0.98  
0.97  
0.96  
0.95  
0.94  
0.93  
0.92  
0.91  
0.90  
0.89  
0.88  
0.87  
0.86  
0.85  
0.84  
0.83  
0.82  
0.81  
0.80  
0.79  
0.78  
0.77  
0.76  
0.75  
0.74  
0.73  
0.72  
0.71  
0.70  
0.69  
0.68  
0.67  
0.66  
0.65  
0.64  
0.63  
0.62  
0.61  
0.60  
0.59  
0.58  
0.57  
0.56  
0.55  
0.54  
0.53  
0.52  
0.51  
0.50  
E
D
C
B
A
9
8
7
6
5
4
3
2
1
98  
97  
96  
95  
94  
93  
92  
91  
90  
8F  
8E  
8D  
8C  
28  
Rev 3.5  
Jun 7, 2019  
IR38265  
BUS VOLTAGE UVLO  
If the input to the Enable pin is derived from the bus voltage by a suitably programmed resistive divider, it can be  
ensured that the device does not turn on until the bus voltage reaches the desired level as shown in Figure 9.  
Only after the bus voltage reaches or exceeds this level and voltage at the Enable pin exceeds its threshold  
(typically 0.6V) will the device be enabled. Therefore, in addition to being logic input pin to enable the converter,  
the Enable feature, with its precise threshold, also allows the user to override the default under-Voltage Lockout  
for the bus voltage (PVin). This is desirable particularly for high output voltage applications, where we might want  
the device to be disabled at least until PVin exceeds the desired output voltage level. Alternatively, the default 8 V  
PVin UVLO threshold may be reconfigured/overridden using the corresponding registers. It should be noted that  
the input voltage is also fed to an ADC through a 21:1 internal resistive divider. However, the digitized input  
voltage is used only for the purposes of reporting the input voltage through a 8-bit register v12_supply [7:0]. It has  
no impact on the bus voltage UVLO, input overvoltage faults and input undervoltage warnings, all of which are  
implemented by using analog comparators to compare the input voltage to the corresponding thresholds  
programmed into the I2C registers. The bus voltage reading as reported by v12_supply has no effect on the input  
feedforward function either.  
12V  
10.2V  
1 V  
PVin  
Vcc  
> 0.6V  
0.6V  
EN_UVLO_START  
EN  
DAC2 (Reference DAC)  
Figure 9: Normal Start up, device turns on when the bus voltage reaches 10.2V. A resistor divider is used at EN pin  
from PVin to turn on the device at 10.2V.  
PVin=Vin  
Vcc  
> 0.6V  
EN  
DAC2 (Reference DAC)  
Figure 10: Recommended startup for Normal operation  
Figure 10 shows the recommended startup sequence for the normal operation of the device, when Enable is used  
as logic input.  
29  
Rev 3.5  
Jun 7, 2019  
IR38265  
PRE-BIAS STARTUP  
The IR38265 can start up into a pre-charged output, which prevents oscillation and disturbances of the output  
voltage.  
The output starts in asynchronous fashion and keeps the synchronous MOSFET (Sync FET) off until the first gate  
signal for control MOSFET (Ctrl FET) is generated. Figure 11 shows a typical Pre-Bias condition at start up. The  
sync FET always starts with a narrow pulse width (12.5% of a switching period) and gradually increases its duty  
cycle with a step of 12.5%, with 16 cycles at each step, until it reaches the steady state value. Figure 12 shows  
the series of 16x8 startup pulses.  
[V]  
Vo  
Pre-Bias  
Voltage  
[Time]  
Figure 11: Pre-Bias startup  
...  
HDRv  
...  
...  
...  
...  
87.5%  
12.5%  
16  
25%  
...  
LDRv  
...  
...  
...  
End of  
PB  
...  
16  
Figure 12: Pre-Bias startup pulses  
SOFT-START (REFERENCE DAC RAMP)  
An internal soft starting DAC controls the output voltage rise and limit the current surge at the start-up. To ensure  
correct start-up, the DAC sequence initiates only after power conversion is enabled when the Enable pin voltage  
exceeds its undervoltage threshold, the PVin bus voltage exceeds its undervoltage threshold and the contents of  
the MTP have been fully loaded into the working registers. Figure 13 shows the waveforms during soft start. The  
output voltage rises with a slew rate of 0.625 mv/us.  
30  
Rev 3.5  
Jun 7, 2019  
IR38265  
Internal Enable  
Reference  
DAC  
Vout  
Ton_rise  
t1  
t 2  
Figure 13: DAC2 (VREF) Soft start  
During the startup sequence the over-current protection (OCP) and over-voltage protection (OVP) are active to  
protect the device against any short circuit or over voltage condition.  
OPERATING FREQUENCY  
Using the corresponding I2C registers, the switching frequency may be programmed between 150 kHz and 1.5  
MHz. For best telemetry accuracy, it is recommended that the following switching frequencies be avoided: 250  
kHz, 300 kHz, 400 kHz, 500 kHz, 600 kHz, 750 kHz, 800 kHz, 1 MHz, 1.2 MHz and 1.5 MHz. Instead, Infineon  
suggests using the following values 251 kHz, 302 kHz, 403 kHz, 505 kHz, 607 kHz, 762 kHz, 813 kHz, 978 kHz,  
1171 kHz and 1454 kHz respectively.  
SHUTDOWN  
In the default configuration, the device can be shutdown by pulling the Enable pin below its 0.4V threshold.  
During shutdown the high side and the low side drivers are turned off. By default, the device exhibits an  
immediate shutdown with no delay and no soft stop.  
Part may also be configured to allow a soft or controlled turned off. If the soft-stop option is used, the output  
voltage slews down at 0.625 mV/us.  
31  
Rev 3.5  
Jun 7, 2019  
IR38265  
CURRENT SENSING, TELEMETRY AND OVER CURRENT PROTECTION  
Current sensing for both, telemetry as well as overcurrent protection is done by sensing the voltage across the  
sync FET RDson. This method enhances the converter’s efficiency, reduces cost by eliminating a current sense  
resistor and any minimizes sensitivity to layout related noise issues. A novel, patented scheme allows  
reconstruction of the average inductor current from the voltage sensed across the Sync FET Rdson. It should be  
noted here that it is this reconstructed average inductor current that is digitized by the ADC and used for output  
current reporting as well as for overcurrent warning, the threshold for which may be set using the I2C commands.  
The current information can be read back through the 8-bit register output_current_byte, which reports the current  
in 1/4 A resolution.  
The Over current (OC) fault protection circuit also uses the voltage sensed across the RDS(on) of the Synchronous  
MOSFET; however, the protection mechanism relies on a fast comparator to compare the sensed signal to the  
overcurrent threshold and does not depend on the ADC or reported current. The current limit scheme uses an  
internal temperature compensated current source that has the same temperature coefficient as the RDS(on) of the  
Synchronous MOSFET. As a result, the over-current trip threshold remains almost constant over temperature.  
Over Current Protection circuitry senses the inductor current flowing through the Synchronous FET closer to the  
valley point. The OCP circuit samples this current for 75 ns typically after the rising edge of the PWM set pulse  
which is an internal signal that has a width of 12.5% of the switching period. The PWM pulse that turns on the  
high side FET starts at the falling edge of the PWM set pulse. This makes valley current sense more robust as  
current is sensed close to the bottom of the inductor downward slope where transient and switching noise is low.  
This helps to prevent false tripping due to noise and transients.  
The actual DC output current limit point will be greater than the valley point by an amount equal to approximately  
half of the peak to peak inductor ripple current. The current limit point will be a function of the inductor value, input  
voltage, output voltage and the frequency of operation. On equation 1, ILimit is the value set when configuring the  
38265 OCP value. The user should account for the inductor ripple to obtain the actual DC output current limit.  
i  
2
IOCP ILIMIT  
(1)  
IOCP  
ILIMIT  
Δi  
= DC current limit hiccup point  
= Current Limit Valley Point  
= Inductor ripple current  
32  
Rev 3.5  
Jun 7, 2019  
IR38265  
Current Limit  
Hiccup  
Tblk_Hiccup  
20 ms  
IL  
0
HDrv  
...  
...  
0
LDrv  
0
PGood  
0
Figure 14: Timing Diagram for Current Limit Hiccup  
In the default configuration, if the overcurrent detection trips the OCP comparator for a total of 8 cycles, the device  
goes into a hiccup mode. The hiccup is performed by de-asserting the internal Enable signal to the analog and  
power conversion circuitry and holding it low for 20 ms.  
Following this, the OCP signal resets and the converter recovers. After every hiccup cycle, the converter stays in  
this mode until the overload or short circuit is removed. This behavior is shown in Figure 14.  
It should be noted that on some units, a false OCP maybe experienced during device start-up due to noise. The  
part will ride through this false OCP due to the pulse by pulse current limiting feature and successfully ramp to the  
correct output voltage.  
Note that the user can reprogram the default overcurrent threshold using I2C. It is recommended that the  
overcurrent threshold be programmed to at least 16A for good accuracy. While these devices will still offer  
overcurrent protection for thresholds programmed lower than these recommended values, the thresholds will not  
be as accurate.  
Also, there is a register than can be reprogrammed using I2C to configure the part to respond to an overcurrent  
fault in one of two ways  
1) Pulse by pulse current limiting for a programmed number of 8 switching cycles followed by a latched  
shutdown.  
2) Pulse by pulse current limiting for a programmed number 8 switching cycles followed by hiccup. This is  
the default explained above.  
The pulse-by-pulse or constant current limiting mechanism is briefly explained below.  
33  
Rev 3.5  
Jun 7, 2019  
IR38265  
IOUT_OC_FAULT_LIMIT  
IL  
20 ms  
0
HDrv  
0
LDrv  
0
CLK  
Fs  
0
OCP High  
1
2
3
4
5
6
7
8
Internal  
Enable  
Figure 15: Pulse by pulse current limiting for 8 cycles, followed by hiccup.  
In Figure 15 above, with the overcurrent response set to pulse-by-pulse current limiting for 8 cycles followed by  
hiccup, the converter is operating at D<0.125 when the overcurrent condition occurs. In such a case, no duty  
cycle limiting is applied.  
IO UT_OC_FAULT_LIMIT  
IL  
0
HDrv  
0
LDrv  
0
CLK  
Fs  
0
OCP High  
1
2
3
4
5
6
7
8
9
10  
11  
...  
Internal  
Enable  
Figure 16: Constant current limiting.  
Figure 16 depicts a case where the overcurrent condition happens when the converter is operating at D>0.5 and  
the overcurrent response has been set to Constant current operation through pulse by pulse current limiting. In  
such a case, after 3 consecutive overcurrent cycles are recognized, the pulse width is dropped such that D=0.5  
and then after 3 more consecutive OCP cycles, to 0.25 and then finally to 0.125 at which it keeps running until the  
total OCP count reaches the programmed maximum following which the part enters hiccup mode. Conversely,  
when the overcurrent condition disappears, the pulse width is restored to its nominal value gradually, by a similar  
mechanism in reverse; every sequence of 4 consecutive cycles in which the current is below the overcurrent  
threshold doubles the duty cycle, so that D goes from 0.125 to 0.25, then to 0.5 and finally to its nominal value.  
34  
Rev 3.5  
Jun 7, 2019  
IR38265  
DIE TEMPERATURE SENSING, TELEMETRY AND THERMAL SHUTDOWN  
On die temperature sensing is used for accurate temperature reporting and over temperature detection. The  
temperature may be read back through the 8-bit register temp_byte, which reports the die temperature in 10C  
resolution, offset by 400C. Thus, the temperature is given by temp_byte +400C.  
The trip threshold is set by default to 125oC. The default over temperature response of the device is to inhibit  
power conversion while the fault is present, followed by automatic restart after the fault condition is cleared.  
Hence, in the default configuration, when trip threshold is exceeded, the internal Enable signal to the power  
conversion circuitry is de-asserted, turning off both MOSFETs.  
Automatic restart is initiated when the sensed temperature drops within the operating range. There is a 25oC  
hysteresis in the thermal shutdown threshold.  
The default overtemperature threshold as well as overtemperature response may be re-configured or overridden  
using the corresponding MTP registers. The devices support three types of responses to an over-temperature  
fault:  
1) Ignore  
2) Inhibit when over temperature condition exists and auto-restart when over temperature condition  
disappears  
3) Latched shutdown.  
REMOTE VOLTAGE SENSING  
True differential remote sensing in the feedback loop is critical to high current applications where the output  
voltage across the load may differ from the output voltage measured locally across an output capacitor at the  
output inductor, and to applications that require die voltage sensing.  
The RS+ and RS- pins form the inputs to a remote sense differential amplifier with high speed, low input offset  
and low input bias current, which ensure accurate voltage sensing and fast transient response in such  
applications.  
The input range for the differential amplifier is limited to 1.5V below the VCC rail. Therefore, for applications in  
which the output voltage is more than 3V, it is recommended to use local sensing, or if remote sensing is a must,  
then the voltage between the RS+ and RS-pins must be divided down to less than 3V using a resistive voltage  
divider. It’s recommended that the divider be placed at the input of the remote sense amplifier and that a low  
impedance such as 499 Ω be used between the RS+ and RS- nodes. A typical schematic for this setup is shown  
on Figure 5. Please note, however, that this modifies the open loop transfer function and requires a change in the  
compensation network to optimally stabilize the loop.  
FEED-FORWARD  
Feed-Forward (F.F.) is an important feature, because it can keep the converter stable and preserve its load  
transient performance when PVin varies over a wide range. The PWM ramp amplitude (Vramp) is proportionally  
changed with PVin to maintain PVin/Vramp almost constant throughout PVin variation range (as shown in Figure  
17). Thus, the control loop bandwidth and phase margin can be maintained constant. Feed-forward function can  
35  
Rev 3.5  
Jun 7, 2019  
IR38265  
also minimize impact on output voltage from fast PVin change. The feedforward is disabled for PVin<4.7V. Hence,  
for PVin<4.7V, a re-calculation of control loop parameters is needed for re-compensation.  
21V  
12V  
12V  
5V  
PVin  
0
PWM Ramp  
Ramp Offset  
0
Figure 17: Timing Diagram for Feed-Forward (F.F.) Function  
LIGHT LOAD EFFICIENCY ENHANCEMENT (AOT)  
These devices implement a diode emulation scheme with Adaptive On Time control or AOT to improve light load  
efficiency. It is based on a COT (Constant On Time) control scheme with some novel advancements that make  
the on-time during diode emulation adaptive and dependent upon the pulse width in constant frequency operation.  
This allows the scheme to be combined with a PWM scheme, while providing relatively smooth transition between  
the two modes of operation. In other words, the switching regulator can operate in AOT mode at light loads and  
automatically switch to PWM at medium and heavy loads and vice versa. Therefore, the regulator will benefit from  
the high efficiency of the AOT mode at light loads, and from the constant frequency and fast transient response of  
the PWM at medium to heavy loads.  
A register bit mfr_fccm bit can be used to enable AOT operation at light load.  
Shortly after the reference voltage has finished ramping up, an internal circuit which is called the “calibration  
circuit” starts operation. It samples the Comp voltage (output of the error amplifier), digitizes it and stores it in a  
register. There is a DAC which converts the value of this register to an analog voltage which is equal to the  
sampled Comp voltage. At this time, the regulator is ready to enter AOT mode if the load condition is appropriate.  
If the load is so low that the inductor current becomes negative before the next SW pulse, the operation can be  
switched to AOT mode. The condition to enter AOT is the occurrence of 8 consecutive inductor current zero  
crossings in eight consecutive switching cycles. If this happens, operation is switched to AOT mode as shown in  
Figure 18Figure 18. The inductor current is sensed using the RDS_ON of the Sync-FET and no direct inductor  
current measuring is required. In AOT mode, just like COT operation, pulses with constant width are generated  
and diode emulation is utilized. This means that a pulse is generated and LDrv is held on until the inductor current  
becomes zero. Then both HDrv and LDrv remain off until the voltage of the sense pin comes down and reaches  
the reference voltage. At this moment the next pulse is generated. The sense pin is connected to the output  
voltage by a resistor divider which has the same ratio as the voltage divider which is connected to the feedback  
pin (Fb).  
36  
Rev 3.5  
Jun 7, 2019  
IR38265  
...  
Vout  
0
8/Fs delay  
Diode  
Emulation  
IL  
...  
0
Ton  
...  
...  
SW  
...  
...  
0
HDrv  
0
LDrv  
...  
...  
0
Reduced Switching  
Frequency  
1/Fs  
Figure 18: Timing Diagram for Reduced Switching Frequency and Diode Emulation in Light Load Condition (AOT  
mode)  
When the load increases beyond a certain value, the control is switched back to PWM through either of the  
following two mechanisms:  
1) If due to the increase in load, the output voltage drops to 95% of the reference voltage.  
2) If Vsense remains below the reference voltage for 3 consecutive inductor current zero-cross events  
It is worth mentioning that in AOT mode, when Vsense comes down to reference voltage level, a new pulse in  
generated only if the inductor current is already zero. If at this time the inductor current (sensed on the Sync-FET)  
is still positive, the new pulse generation is postponed till the current decays to zero. The second condition  
mentioned above usually happens when the load is gradually increased.  
It should be noted that in tracking mode, AOT operation is disabled and the device can only operate in continuous  
conduction mode even at light loads.  
AOT is disabled during output voltage transitions. It is enabled only after reference voltage finishes its ramp (up or  
down) and the calibration circuit has sampled and held the new Comp voltage.  
In general, AOT operation is more jittery and noisier than FCCM operation, where the switching frequency may  
vary from cycle to cycle, giving increased Vout ripple and noisier, inconsistent telemetry. Therefore, it is  
recommended to use FCCM mode of operation as far as possible.  
37  
Rev 3.5  
Jun 7, 2019  
IR38265  
OUTPUT VOLTAGE SENSING, TELEMETRY AND FAULTS  
In the IR38265, the voltage sense and regulation circuits are decoupled, enabling ease of testing as well as  
redundancy. In order to do this, the device uses the sense voltage at the dedicated Vsns pin for output voltage  
reporting (in 1/64 V resolution, using 2 registers: output_voltage_msb [2:0] and output_voltage_lsb [7:0]) as well  
as for power good detection and output overvoltage protection.  
Power good detection and output overvoltage detection rely on fast analog comparator circuits, whereas  
overvoltage warnings as well as undervoltage faults and warnings rely on comparing the digitized Vsns to the  
corresponding thresholds programmed in the MTP. The thresholds are reprogrammable using I2C.  
Power Good Output  
Power Good is asserted when the output voltage is within the tolerance band of the target voltage set in the  
register selected by the VIDSELx pins. Following this, the Power Good signal remains asserted irrespective of  
any output voltage transitions and is de-asserted only in the event of a fault that shuts down power conversion.  
Fault DAC  
0
Reference DAC  
0
Vset+/-TOB  
Vsns  
0
PGD  
0
Figure 19: Power Good in PVID mode, Vboot >0 V  
Over-Voltage Protection (OVP)  
Over-voltage protection is achieved by comparing sense pin voltage Vsns to a configurable overvoltage threshold.  
The OVP threshold may be reprogrammed to within 655 mV of the output voltage (for output voltages lower than  
2.555V, without any resistive divider on the Fb pin), using I2C. For an OVP threshold programmed to be more  
than 655 mV greater than the output voltage, the effective OV threshold ceases to be an absolute value and  
instead tracks the output voltage with a 655 mV offset.  
When Vsns exceeds the over voltage threshold, an over voltage trip signal asserts after 200ns (typ.) delay. The  
default response is that the high side drive signal HDrv is latched off immediately and PGood flags are set low.  
The low side drive signal is kept on until the Vsns voltage drops below the threshold. HDrv remains latched off  
until a reset is performed by cycling either Vcc or Enable or the OPERATION command. In addition to the default  
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response described above, I2C can be used to configure the device such that Vout overvoltage faults are ignored  
and the converter remains enabled..  
Vsns voltage is set by an external resistive voltage divider connected to the output. This divider ratio must match  
the divider used on the feedback pin or on the RS+ pin.  
DAC1+OV_OFFSET_DAC  
Vout  
DAC1  
hysteresis  
0
HDrv  
0
LDrv  
0
Comp  
0
PGood  
0
200 ns  
200 ns  
Figure 20: Timing Diagram for OVP in non-tracking mode  
MINIMUM ON TIME CONSIDERATIONS  
The minimum ON time is the shortest amount of time for Ctrl FET to be reliably turned on. This is a very critical  
parameter for low duty cycle, high frequency applications. In the conventional approach, when the error amplifier  
output is near the bottom of the ramp waveform with which it is compared to generate the PWM output,  
propagation delays can be high enough to cause pulse skipping, and hence limit the minimum pulse width that  
can be realized. Moreover, in the conventional approach, the bottom of the ramp often presents a high gain region  
to the error amplifier output, making the modulator more susceptible to noise and requiring the use of lower  
control loop bandwidth to prevent noise, jitter and pulse skipping.  
Infineon has developed a proprietary scheme to improve and enhance the minimum pulse width which minimizes  
these delays and hence, allows stable operation with pulse-widths as small as 35ns. At the same time, this  
scheme also has greater noise immunity, thus allowing stable, jitter free operation down to very low pulse widths  
even with a high control loop bandwidth, thus reducing the required output capacitance.  
Any design or application using these devices must ensure operation with a pulse width that is higher than the  
minimum on-time and at least 50 ns of on-time is recommended in the application. This is necessary for the circuit  
to operate without jitter and pulse-skipping, which can cause high inductor current ripple and high output voltage  
ripple.  
Vout  
Fs PV Fs  
D
ton   
(2)  
in  
In any application that uses these devices, the following condition must be satisfied:  
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(3)  
(4)  
ton(min) ton  
Vout  
ton(min)  
PV Fs  
in  
Vout  
(5)  
PV Fs   
in  
ton(min)  
The minimum output voltage is limited by the reference voltage and hence Vout(min) = 0.5V. Therefore, for Vout(min)  
0.5V,  
=
Vout  
(6)  
PV Fs   
in  
ton(min)  
0.5V  
PVin Fs   
10 V/μs  
50ns  
Therefore, at the maximum recommended input voltage 16V and minimum output voltage, the converter should  
be designed at a switching frequency that does not exceed 625 kHz. Conversely, for operation at the maximum  
recommended operating frequency (1.5 MHz) and minimum output voltage (0.5V), the input voltage (PVin) should  
not exceed 6.67 V, otherwise pulse skipping may happen.  
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MAXIMUM DUTY RATIO  
An upper limit on the operating duty ratio is imposed by the larger of a) A fixed off time (dominant at high  
switching frequencies) b) blanking provided by the PWMSet or clock pulse, which has a pulse width that is 1/8 of  
the switching period. The latter mechanism is dominant at lower switching frequencies (typically below 1.25 MHz).  
This upper limit ensures that the Sync FET turns on for a long enough duration to allow recharging the bootstrap  
capacitor and also allows current sensing. Figure 21 shows a plot of the maximum duty ratio vs. the switching  
frequency with built in input voltage feed forward mechanism.  
Figure 21: Maximum duty cycle vs. switching frequency  
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BOOTSTRAP CAPACITOR  
To drive the Control FET, it is necessary to supply a gate voltage at least 4V greater than the voltage at the SW  
pin, which is connected to the source of the Control FET. This is achieved by using a bootstrap configuration,  
which comprises the internal bootstrap diode and an external bootstrap capacitor (C1). Typically a 0.1uF  
capacitor is used. A layout placement for a 0 ohm resistor in series with the capacitor is also recommended. For  
PVin> 14V, a 1 ohm series resistor is required. The operation of the circuit is as follows: When the sync FET is  
turned on, the capacitor node connected to SW is pulled down to ground. The capacitor charges towards Vcc  
through the internal bootstrap diode (Figure 22), which has a forward voltage drop VD. The voltage Vc across the  
bootstrap capacitor C1 is approximately given as:  
(7)  
Vc Vcc VD  
When the control FET turns on in the next cycle, the capacitor node connected to SW rises to the bus voltage  
PVin. However, if the value of C1 is appropriately chosen, the voltage Vc across C1 remains approximately  
unchanged and the voltage at the Boot pin becomes:  
(8)  
VBoot PV V VD  
in  
cc  
Cvin  
PVIN  
+ VD  
-
Boot  
V
cc  
+
Vc  
-
C1  
SW  
L
IR38265  
PGnd  
Figure 22: Bootstrap circuit to generate high side drive voltage  
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LOOP COMPENSATION  
Feedback loop compensation is achieved using standard Type III techniques and the compensation values can  
be easily calculated using Infineon’s design tool. The design tool can also be used to predict the control  
bandwidth and phase margin for the loop for any set of user defined compensation component values. For a  
theoretical understanding of the calculations used, please refer to Infineon’s Application Note AN-1162  
“Compensator Design Procedure for Buck Converter with Voltage-Mode Error-Amplifier”.  
DYNAMIC VID COMPENSATION  
This family of devices uses an analog control scheme with voltage mode control. In this scheme, the compensator  
acts on the Vout signal and not just on the error signal. For load and line transients, with a steady and unchanging  
reference voltage, this has the same dynamic characteristics as for a compensator that acts on only the error  
signal. However, for reference voltage changes, as in the case of Dynamic VID, the dynamics are altered. A  
proprietary dynamic VID compensation scheme allows the dynamic VID response to be tuned optimally to the  
feedback compensator values. Once properly optimized, the output voltage will follow the DAC more closely  
during a positive dynamic VID, irrespective of whether the new voltage is commanded by using I2C or by using  
the 3 VIDSELx pins to select a different register and target voltage. Infineon’s design tool will allow the user to  
quickly and conveniently calculate the dynamic VID compensation parameters for optimal dynamic VID response.  
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LAYOUT RECOMMENDATIONS  
The layout is very important when designing high frequency switching converters. Layout will affect noise pickup  
and can cause a good design to perform with less than expected results.  
Make the connections for the power components in the top layer with wide, copper filled areas or polygons. In  
general, it is desirable to make proper use of power planes and polygons for power distribution and heat  
dissipation.  
The input capacitors, inductor, output capacitors and the device should be as close to each other as possible.  
This helps to reduce the EMI radiated by the power traces due to the high switching currents through them. Place  
the input capacitor directly at the PVin pin of IR38x6x.  
Power vias should be at least 20/10 mil and a good rule of thumb is to design at 2A/via.  
The feedback part of the system should be kept away from the inductor and other noise sources.  
The critical bypass components such as capacitors for Vin, VCC and 1.8V should be close to their respective  
pins. It is important to place the feedback components including feedback resistors and compensation  
components close to Fb and Comp pins.  
In a multilayer PCB use one layer as a power ground plane and have a control circuit ground (analog ground), to  
which all signals are referenced. The goal is to localize the high current path to a separate loop that does not  
interfere with the more sensitive analog control functions. These two grounds must be connected together on the  
PC board layout at a single point. It is recommended to place all the compensation parts over the analog ground  
plane in top layer.  
The Power QFN is a thermally enhanced package. Based on thermal performance it is recommended to use at  
least a 6-layers PCB. To effectively remove heat from the device the exposed pad should be connected to the  
ground plane using vias.  
IR38265 has 3 pins, SCL, SDA and SALERT# that are used for I2C communication. It is recommended that the  
traces used for these communication lines be at least 10 mils wide with spacing between the SCL and SDA traces  
that is at least 2-3 times the trace width.  
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I2C PROTOCOLS  
All registers may be accessed using I2C protocols. I2C allows the use of a simple format whereas PMBus provides error  
checking capability. Figure 23 shows the I2C format employed by IC.  
S: Start Condition  
1
S
7
1
1
A
8
1
A
8
1
A
1
P
A: Acknowledge (0')  
N: Not Acknowledge (1')  
Sr: Repeated Start Condition  
P: Stop Condition  
Slave  
Register  
Address  
WRITE  
READ  
W
Data Byte  
Address  
R: Read (1')  
1
7
1
1
P
1
S
7
1
8
1
S
1
R
8
W: Write (0')  
Slave  
Register  
Address  
Slave  
A
Data Byte  
A
A
N
W
Address  
Address  
PEC: Packet Error Checking  
*: Present if PEC is enabled  
: Master to Slave  
: Slave to Master  
Figure 23: I2C Format  
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PCB PADS AND COMPONENT  
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PCB COPPER AND SOLDER RESIST (PAD SIZES)  
PCB COPPER AND SOLDER RESIST (PAD SPACING)  
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SOLDER PASTE STENCIL (PAD SIZES)  
SOLDER PASTE STENCIL (PAD SPACING)  
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MARKING INFORMATION FOR FINAL PRODUCTION  
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MARKING INFORMATION FOR EARLY PRODUCTION  
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PACKAGE INFORMATION  
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ENVIRONMENTAL QUALIFICATIONS  
Industrial  
Qualification Level  
Moisture Sensitivity Level  
Machine Model  
5mm x 7mm PQFN  
MSL 2 260C  
JEDEC Class A  
JEDEC Class 1C  
JEDEC Class 3  
(JESD22-A115A)  
Human Body Model  
(JESD22-A114F)  
ESD  
Charged Device Model  
(JESD22-C101F)  
RoHS Compliant  
Yes (with Exemption 7a)  
† Qualification standards can be found at International Rectifier web site: http://www.irf.com  
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REVISION HISTORY  
3.0  
3.1  
3.2  
3.3  
3.4  
3.5  
3/9/2017  
3/20/2017  
5/8/2017  
12/12/2017  
9/6/2018  
6/7/2019  
Initial Release.  
Changed 1.8V LDO regulation current to 1 mA, updated stencil drawings.  
Added requirement of 1 ohm series resistor for PVin>14V.  
Added recommendation to use 10uF bypass capacitor at P1V8 pin. Added note about using a 4.99K  
resistor for the VIDSEL pins section. Updated OCP and other functionality descriptions.  
Updated package marking information on IC. Added thermal derating curves.  
Removed comments in the revision history that came before the initial release. Post Rev 3.0  
comments.  
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Published by  
Infineon Technologies AG  
81726 München, Germany  
© Infineon Technologies AG 2015  
All Rights Reserved.  
IMPORTANT NOTICE  
The information given in this document shall in no event be regarded as a guarantee of conditions or characteristics  
(“Beschaffenheitsgarantie”). With respect to any examples, hints or any typical values stated herein and/or any information  
regarding the application of the product, 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.  
In addition, any information given in this document is subject to customer’s compliance with its obligations stated in this  
document and any applicable legal requirements, norms and standards concerning customer’s products and any use of the  
product of Infineon Technologies in customer’s applications.  
The data contained in this document is exclusively intended for technically trained staff. It is the responsibility of customer’s  
technical departments to evaluate the suitability of the product for the intended application and the completeness of the  
product information given in this document with respect to such application.  
For further information on the product, technology, delivery terms and conditions and prices please contact your nearest  
Infineon Technologies office (www.infineon.com).  
WARNINGS  
Due to technical requirements products may contain dangerous substances. For information on the types in question please  
contact your nearest Infineon Technologies office.  
Except as otherwise explicitly approved by Infineon Technologies in a written document signed by authorized representatives  
of Infineon Technologies, Infineon Technologies’ products may not be used in any applications where a failure of the product  
or any consequences of the use thereof can reasonably be expected to result in personal injury.  
55  
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