XRP6124
Non-Synchronous PFET Step-Down Controller
January 2011
Rev. 1.1.0
GENERAL DESCRIPTION
The XRP6124 is a non synchronous step down
(buck) controller for up to 5Amps point of
loads. A wide 3V to 30V input voltage range
allows for single supply operations from
industry standard 3.3V, 5V, 12V and 24V
power rails.
With a proprietary Constant On-Time (COT)
control scheme, the XRP6124 provides
extremely fast line and load transient response
while the operating frequency remains nearly
constant. It requires no loop compensation
hence simplifying circuit implementation and
reducing overall component count. The
XRP76124 also implements an emulated ESR
circuitry allowing usage of ceramic output
capacitors and insuring stable operations
without the use of extra external components.
Built-in soft start prevents high inrush currents
while under voltage lock-out and output short
protections insure safe operations under
abnormal operating conditions.
The XRP6124 is available in a RoHS compliant,
green/halogen free space-saving 5-pin SOT23
package.
APPLICATIONS
•
Point of Load Conversions
•
Audio-Video Equipments
•
Industrial and Medical Equipments
•
Distributed Power Architecture
FEATURES
•
5A Point-of-Load Capable
−
Down to 1.2V Output Voltage Conversion
•
Wide Input Voltage Range
−
3V to 18V: XRP6124
−
4.5V to 30V: XRP6124HV
•
Constant On-Time Operations
−
Constant Frequency Operations
−
No External Compensation
−
Supports Ceramic Output Capacitors
•
Built-in 2ms Soft Start
•
Short Circuit Protection
•
<1µA shutdown current
•
RoHS Compliant, Green/Halogen Free
5-pin SOT23 Package
TYPICAL APPLICATION DIAGRAM
Figure 1: XRP6124 Application Diagram
Exar Corporation
48720 Kato Road, Fremont CA 94538, USA
www.exar.com
Tel. +1 510 668-7000 – Fax. +1 510 668-7001
XRP6124
Non-Synchronous PFET Step-Down Controller
ABSOLUTE MAXIMUM RATINGS
These are stress ratings only and functional operation of
the device at these ratings or any other above those
indicated in the operation sections of the specifications
below is not implied. Exposure to absolute maximum
rating conditions for extended periods of time may affect
reliability.
V
IN
(XRP6124) ............................................ -0.3V to 20V
V
IN
(XRP6124HV) ........................................ -0.3V to 32V
GATE ...................................................... VIN-GATE<8V
FB, EN ..................................................... -0.3V to 5.5V
Storage Temperature .............................. -65°C to 150°C
Power Dissipation ................................ Internally Limited
Lead Temperature (Soldering, 10 sec) ................... 300°C
ESD Rating (HBM - Human Body Model) .................... 2kV
OPERATING RATINGS
Input Voltage Range V
IN
(XRP6124)................ 3.0V to 18V
Input Voltage Range V
IN
(XRP6124HV)............ 4.5V to 30V
Junction Temperature Range ....................-40°C to 125°C
Thermal Resistance
θ
JA
.....................................191°C/W
ELECTRICAL SPECIFICATIONS
Specifications are for an Operating Junction Temperature of T
J
= 25°C only; limits applying over the full Operating Junction
Temperature range are denoted by a “•”. Minimum and Maximum limits are guaranteed through test, design, or statistical
correlation. Typical values represent the most likely parametric norm at T
J
= 25°C, and are provided for reference purposes
only. Unless otherwise indicated, V
IN
= 3.0V to 18V, T
J
= –40°C to 125°C.
Parameter
UVLO Turn-On Threshold
UVLO Turn-On Threshold
UVLO Hysteresis
Operating Input Voltage Range
Shutdown VIN Current
Operating VIN Current
Reference Voltage
VSC_TH, Feedback pin Short
Circuit Latch Threshold
T
ON
, Switch On-Time
T
ON
, Switch On-Time
T
OFF_MIN
, Minimum Off-Time
Soft Start Time
EN Turn-On Threshold
EN Turn-Off Threshold
EN Bias Current
Gate Driver Pull-Down
Resistance
Gate Driver Pull-up Resistance
tr, gate rise time
tf, gate fall time
VIN - GATE voltage difference
VIN - GATE voltage difference
5.5
2.6
0.01
6
5
45
35
6.4
8
2
1
0.1
9
8
0.792
0.784
0.50
0.4
0.4
3.0
4.5
1.5
0.5
0.8
0.8
0.55
0.5
0.5
250
2
Min.
2.5
3.8
Typ.
2.8
4.2
0.1
18
30
3
1
0.808
0.816
0.65
0.6
0.6
350
Max.
3.0
4.5
Units
V
V
V
V
V
µA
mA
V
V
V
µs
µs
ns
ms
V
V
µA
Ω
Ω
ns
ns
V
V
•
•
C
GATE
=1nF
C
GATE
=1nF
VIN=12V
VIN=3.0V
•
•
•
•
•
V
IN
=12V, XRP6124
V
IN
=24V, XRP6124HV
V
IN
=12V
•
•
XRP6124
XRP6124HV
EN=0V, V
IN
=12V
VFB=1.2V and after fault
•
•
XRP6124
XRP6124HV
Conditions
© 2011 Exar Corporation
2/12
Rev. 1.1.0
XRP6124
Non-Synchronous PFET Step-Down Controller
BLOCK DIAGRAM
Figure 2: XRP6124 Block Diagram
PIN ASSIGNMENT
EN
1
5
VI N
GN D
2
XRP61 24
FB
3
4
GAT E
Figure 3: XRP6124 Pin Assignment
PIN DESCRIPTION
Name
EN
GND
FB
GATE
VIN
Pin Number
1
2
3
4
5
Ground
Feedback pin
Gate Pin. Connect to gate of PFET. This pin pulls the gate of the PFET approximately
6V below Vin in order to turn on the FET. For 6V>VIN>3V the gate pulls to within 0.4V
of ground. Therefore a PFET with a gate rating of 2.6V or lower should be used.
Input Voltage
Description
Enable Pin. Actively pull high to enable the part.
ORDERING INFORMATION
Part Number
XRP6124ES0.5-F
XRP6124ESTR0.5-F
XRP6124HVES0.5-F
XRP6124HVESTR0.5-F
XRP6124EVB
Temperature
Range
-40°C≤T
J
≤125°C
-40°C≤T
J
≤125°C
-40°C≤T
J
≤125°C
-40°C≤T
J
≤125°C
XRP6124 Evaluation Board
Marking
Package
5-pin SOT23
5-pin SOT23
Packing
Quantity
Bulk
Bulk
Note 1
Halogen Free
Halogen Free
Note 2
0.5µs/18V max
0.5µs/18V max
0.5µs/30V max
0.5µs/30V max
5-pin SOT23 2.5K/Tape & Reel Halogen Free
5-pin SOT23 2.5K/Tape & Reel Halogen Free
“YY” = Year – “WW” = Work Week – “X” = Lot Number
© 2011 Exar Corporation
3/12
Rev. 1.1.0
XRP6124
Non-Synchronous PFET Step-Down Controller
TYPICAL PERFORMANCE CHARACTERISTICS
All data taken at T
J
= T
A
= 25°C, unless otherwise specified – Curves are based on Schematic and BOM from Application
Information section of this datasheet. Refer to figure 20 for XRP6124 and to figure 21 for XRP6124HV.
Fig. 4: Efficiency versus I
OUT
, V
IN
=12V
Fig. 5: Efficiency versus I
OUT
, V
IN
=24V
Fig. 6: T
ON
versus V
IN
Fig. 7: T
ON
versus V
IN
Fig. 8: Load Regulation
Fig. 9: Load Regulation
© 2011 Exar Corporation
4/12
Rev. 1.1.0
XRP6124
Non-Synchronous PFET Step-Down Controller
XRP6124ES0.5-F
Fig. 10: Line Regulation
Fig. 11: Line Regulation
V
OUT
AC coupled
10mV/div
XRP6124ES0.5-F
V
OUT
AC coupled
20mV/div
LX
20V/div
XRP6124HVES0.5-F
LX
10V/div
IL
2A/div
1µs/div
IL
2A/div
2µs/div
Fig. 12: Steady state, V
IN
=12V, V
OUT
=3.3V, I
OUT
=3A
Fig. 13: Steady state, V
IN
=24V, V
OUT
=5.0V, I
OUT
=3A
XRP6124ES0.5-F
XRP6124HVES0.5-F
90mV
V
OUT
AC coupled
100mV/div
V
OUT
AC coupled
200mV/div
180mV
I
OUT
1A/div
10µs/div
I
OUT
1A/div
20µs/div
Fig. 14: Load step transient response, 1.4A-3A-1.4A
Fig. 15: Load step transient response, 1.4A-3A-1.4A
© 2011 Exar Corporation
5/12
Rev. 1.1.0
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