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PDF IR3640MPBF Data sheet ( Hoja de datos )
| Número de pieza | IR3640MPBF | |
| Descripción | HIGH FREQUENCY SYNCHRONOUS PWM BUCK CONTROLLER | |
| Fabricantes | International Rectifier | |
| Logotipo |  |
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PD97401
IR3640MPBF
HIGH FREQUENCY SYNCHRONOUS PWM BUCK CONTROLLER
Features
• 4.5V to 5.5V external supply
• Wide Input voltage from 1.5V to 24V
• Output voltage range: 0.7V to 0.9*Vin
• Programmable switching frequency up to 1.5MHz
• Programmable Soft-start
• Hiccup mode over current protection using Rds(on)
sensing
• Programmable OCP
• Reference voltage 0.7V (+/-1%, 0oC <Tj<125oC)
• Enhanced Pre-bias start up
• Output voltage tracking
• Integrated MOSFET drivers and bootstrap diode
• Operating temp: -40oC <Tj<125oC
• External synchronization
• Power Good output
• Thermal shut down
• Over voltage protection
• Enable Input with voltage monitoring capability
• Pb-Free & Halogen-Free (RoHS Compliant)
• 20 -Lead MLPQ package (3mmx4mm)
Applications
• Point of Load Power Architectures
• Server & Netcom Applications
• Game Consoles
• General DC/DC Converters
Description
The IR3640M is a synchronous Buck PWM controller
designed for performance demanding DC/DC
applications. The single loop voltage mode
architecture simplifies design while delivery precise
output voltage regulation and fast transient response.
Because of its wide input and output voltage range it
can be used in a large variety of point of load
applications within a system and across different
markets.
The part is designed to drive a pair of N-Channel
MOSFETs from 250kHz to 1.5Mhz switching
frequency giving designers the flexibility to optimize
the solution for best efficiency or smallest footprint.
The output voltage can be precisely regulated from as
low as 0.7V within a tolerance of +/-1% over
temperature, line and load variations.
The device also integrates a diversity of features
including; programmable soft start, pre-bias start up,
voltage tracking, external synchronization, enable
input and Power Good output. Fault protection
features include thermal shutdown, over voltage and
over current shutdown and under voltage lock out.
Typical Application
06/15/2009
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IR3640MPBF
Recommended Operating Conditions
Symbol
Vcc and PVcc
Fs
Tj
Definition
Supply voltages
Operating frequency
Junction temperature
Min
4.5
225
-40
Max
5.5
1650
125
Units
V
kHz
oC
Electrical Specifications
Unless otherwise specified, these specification apply over 4.5V<Vcc<5.5V, 0oC<Tj<125oC
Typical values are specified at 25oC
Parameter
SYM
Test Condition
Min TYP MAX Units
Voltage Accuracy
Regulated voltage at Fb
VFb
0.7
Accuracy
0oC<Tj<125oC
-1.0
+1.0
-40oC<Tj<125oC, Note3
-2
+2
Supply Current
Vcc Supply Current
(Standby)
Vcc Supply Current
(Dyn)
Vcc Supply current
Icc (Standby)
Icc (Dynamic)
Ibias
No Switching, Enable low
Vcc=5V, Freq=600kHz,
Enable high, CLOAD_H=2.2nF
CLOAD_L=4.4nF
Vcc=5V, Freq=600kHz,
Enable high, Cload=Open
500
40
6
Under Voltage Lockout / Enable
Vcc-Threshold-Start
Vcc-Threshold-Stop
Vcc_UVLO_Start Vcc Rising Trip Level
Vcc_UVLO_Stop Vcc Falling Trip Level
4.06
3.76
4.26
3.96
4.46
4.16
V
%
μA
mA
Vcc-Hysteresis
Vcc-Hys
Enable Threshold-Start
Enable Threshold-Stop
En_UVLO_Start Enable Rising Trip Level
En_UVLO_Stop Enable Falling Trip Level
Enable-Hysteresis
En_Hys
Enable
Current
Leakage
Oscillator
Rt Voltage
Frequency
Ramp Amplitude
Ramp Offset
Ien
FS
Vramp
Ramp (os)
Enable=3.3V
Rt=59K
Rt=28.7K
Rt=9.31K
Note4
Note4
0.25 0.3 0.38
1.14 1.2 1.36
0.9 1.0 1.06
0.16 0.20 0.25
18
V
μA
0.665
225
450
1350
0.7
250
500
1500
1.8
0.6
0.735
275
550
1650
V
kHz
Vp-p
V
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IR3640MPBF
Operating Frequency
The switching frequency can be programmed
between 250kHz – 1500kHz by using an external
resistor from Rt to Gnd. Table 1 tabulates the
oscillator frequency versus Rt. Trailing edge
modulation is used for generating PWM
signal(Fig.7) .
Table 1. Switching Frequency and
IOCSet vs. External Resistor (Rt)
Rt (kΩ)
47.5
Fs (kHz)
300
Iocset (μA)
29.4
35.7 400
39.2
28.7 500
48.7
23.7 600
59.07
20.5 700
68.2
17.8 800
78.6
15.8 900
88.6
14.3
1000
97.9
12.7
1100
110.2
11.5
1200
121.7
10.7
1300
130.8
9.76
1400
143.4
9.31
1500
150.3
Ramp
Over-Current Protection
The over current protection is performed by
sensing current through the RDS(on) of low side
MOSFET. This method enhances the converter’s
efficiency and reduce cost by eliminating a
current sense resistor. As shown in Fig. 8, an
external resistor (ROCset is connected between
OCSet pin and the drain of low side MOSFET
(Q2) which sets the current limit set point.
The internal current source develops a voltage
across RSET. An internal current source sources
current (IOCSet ) out of the OCSet pin. This
current is a function of the switching frequency
and hence, of Rt. Table 1. shows IOCSet at
different switching frequencies.
IOCSet (μA)
=
1400
Rt (kΩ)
- -(2)
I OCSET
IR3640
Hiccup
Control
OCSet RSET
Q1
L1
Q2
VOUT
VC
Clock
Cntl gate
Sync gate
Fig. 7: Trailing-edge Modulation
Frequency Synchronization
The IR3640 is capable of accepting an external
digital synchronization signal. Synchronization
will be enabled by the rising edge at an external
clock. The switching frequency is set by
external resistor (Rt). During synchronization, Rt
is selected such that the free running frequency
is 20% below the synchronization frequency.
When unused, the sync pin will remain floating
and is noise immune.
Fig. 8: Connection of over current sensing resistor
When the low side MOSFET is turned on, the
inductor current flows through the Q2 and results
a voltage which is given by:
VOCSet = ( IOCSet∗ ROCSet ) − ( RDS(on) ∗ IL ) - -(3)
An over current is detected if the OCSet pin goes
below ground. Hence, at the current limit
threshold, VOCset=0. Then, for a current limit
setting ILimit, ROCSet is calculated as follows:
ROCSet
=
R
*DS (on)
IOCSet
I Limit
- -(4)
06/15/2009
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| PDF Descargar | [ Datasheet IR3640MPBF.PDF ] | |
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