XR76201EVB [EXAR]
40V PowerBloxTM 1.5A Synchronous Step-Down COT Regulator;
| 型号： | XR76201EVB |
| 厂家： | 
EXAR CORPORATION |
| 描述： | 40V PowerBloxTM 1.5A Synchronous Step-Down COT Regulator |
| 文件： | 总16页 (文件大小：1464K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
XR76201
40V PowerBloxTM 1.5A Synchronous
Step-Down COT Regulator
Description
FEATURES
The XR76201 is a synchronous step-down regulator combining the
controller, drivers, bootstrap diode and MOSFETs in a single package
for point-of-load supplies. The XR76201 is capable of supplying
steady state loads of 1.5A. A wide 5V to 40V input voltage range
allows for single supply operation from 12V battery systems required
to withstand load dump, industry standard 24V 10ꢀ, 18V to 36V, and
rectified 18VAC and 24VAC rails.
ꢀ■
Controller, drivers, bootstrap diode and
MOSFETs integrated in one package
1.5A step-down regulator
ꢀ■
Wide 5V to 40V input voltage range
>0.6V adjustable output voltage
Proprietary constant on-time control
No loop compensation required
Stable ceramic output capacitor
operation
ꢀ■
With a proprietary emulated current mode Constant On-Time (COT)
control scheme, the XR76201 provides extremely fast line and load
transient response using ceramic output capacitors. They require
no loop compensation, simplifying circuit implementation and
reducing overall component count. The control loop also provides
0.05ꢀ load and 0.15ꢀ line regulation and maintains constant
operating frequency. A selectable power saving mode allows the user
to operate in Discontinuous Conduction Mode (DCM) at light current
loads thereby significantly increasing the converter efficiency.
Programmable 100ns to 1µs on-time
Constant 400kHz to 800kHz
frequency
Selectable CCM or CCM/DCM
CCM/DCM for high efficiency at
light-load
ꢀ■
CCM for constant frequency at
light-load
Programmable hiccup current limit with
thermal compensation
ꢀ■
A host of protection features, including overcurrent, over temperature,
short-circuit and UVLO, helps achieve safe operation under abnormal
operating conditions.
ꢀ■
ꢀ■
ꢀ■
Precision enable and power good flag
Programmable soft-start
30-pin 5mm x 5mm QFN package
The XR76201 is available in a RoHS-compliant, green/halogen-free
space-saving 5mm x 5mm QFN package.
APPLICATIONS
ꢀ■
Automotive systems
Industrial
ꢀ■
ꢀ■
Military
Ordering Information – back page
Typical Application
3.340
3.330
3.320
3.310
3.300
3.290
3.280
3.270
3.260
V
IN
VIN
PVIN
BST
SW
C
BST
ENABLE/MODE
EN/MODE
PGOOD
VCC
V
L1
POWER GOOD
OUT
C
IN
R
PGOOD
R
LIM
XR76201
SS
ILIM
FB
C
R
FF
1
C
OUT
TON
C
C
SS
R
VCC
ON
R
2
AGND
PGND
5
10
15
20
25
30
35
40
V
(V)
IN
Figure 1. Typical Application
Figure 2. Line Regulation
REV1A
1/16
XR76201
Absolute Maximum Ratings
Operating Conditions
Stresses beyond the limits listed below may cause
permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect
device reliability and lifetime.
PV ......................................................................5V to 40V
IN
V
........................................................................5V to 40V
IN
SW, ILIM...........................................................-1V to 40V(1)
PGOOD, VCC, TON, SS, EN, FB................... -0.3V to 5.5V
Switching frequency ............................ 400kHz to 800kHz(3)
Junction temperature range......................... -40°C to 125°C
PV , V .......................................................... -0.3V to 43V
IN
IN
V
CC
................................................................. -0.3V to 6.0V
BST................................................................-0.3V to 48V(1)
BST-SW............................................................. -0.3V to 6V
SW, ILIM........................................................ -1V to 43V(1)(2)
ALL other pins .....................................-0.3V to VCC + 0.3V
Storage temperature.................................... -65°C to 150°C
Junction temperature................................................. 150°C
Power dissipation ...................................... Internally limited
Lead temperature (soldering, 10 sec)........................ 300°C
ESD rating (HBM - Human Body Model)....................... 2kV
JEDEC51 package thermal resistance, θ .............28°C/W
JA
Package power dissipation at 25°C.............................3.6W
NOTES:
1. No external voltage applied.
2. SW pin’s minimum DC range is -1V, transient is -5V for less than 50ns.
3. Recommended frequency for optimum performance.
Electrical Characteristics
Unless otherwise noted: T = 25°C, V = 24V, BST = V , SW = AGND = PGND = 0V, C = 4.7µF. Limits applying over
J
IN
CC
VCC
the full operating temperature range are denoted by a •.
Symbol
Parameter
Conditions
•
Min
Typ
Max
Units
Power Supply Characteristics
V
Input voltage range
V
regulating
•
•
5.5
40
2
V
IN
CC
I
I
I
V
input supply current
input supply current
Not switching, V = 24V, V = 0.7V
0.7
12
1
mA
mA
µA
VIN
VIN
OFF
IN
IN
IN
FB
V
f = 300kHz, R = 215k, V = 0.58V
ON
FB
Shutdown current
Enable = 0V, V = 12V
IN
Enable and Under-Voltage Lock-Out UVLO
V
EN pin rising threshold
EN pin hysteresis
•
•
•
1.8
2.8
1.9
70
2.0
3.1
V
IH_EN_1
EN_H_1
V
mV
EN pin rising threshold for DCM/CCM
operation
V
V
3.0
V
IH_EN_2
EN_H_2
EN pin hysteresis
100
4.25
230
mV
V
V
CC
V
CC
UVLO start threshold, rising edge
UVLO hysteresis
4.00
4.40
mV
REV1A
2/16
XR76201
Electrical Characteristics (Continued)
Unless otherwise noted: T = 25°C, V = 24V, BST = V , SW = AGND = PGND = 0V, C = 4.7µF. Limits applying over
J
IN
CC
VCC
the full operating temperature range are denoted by a •.
Symbol
Parameter
Conditions
•
•
Min
Typ
Max
Units
Reference Voltage
0.596
0.594
0.600
0.600
0.604
0.606
V
V
V
REF
Reference voltage
V = 5.5V to 40V, V regulating
IN CC
CCM, closed loop, V = 5.5V-40V, applies to
IN
DC line regulation
DC load regulation
0.15
0.05
ꢀ
ꢀ
any C
OUT
CCM, closed loop, applies to any C
OUT
Programmable Constant On-Time
t
On-time 1
R
= 6.04k, V = 24V
•
•
85
100
830
117
980
ns
ON1
ON
IN
V
OUT
= 1.8V, V = 24V, R = 6.04k,
IN ON
= 1.5A
f Corresponding to on-time 1
710
kHz
I
OUT
t
t
t
Minimum programmable on-time
On-time 2
R
R
R
= 6.04k, V = 24V
85
100
205
479
117
236
550
ns
ns
ns
ON(MIN)
ON2
ON
IN
= 14k, V = 24V
•
•
174
407
ON
IN
On-time 3
= 35.7k, V = 24V
IN
ON3
ON
V
= 1.8V, V = 24V, R = 14k,
IN ON
= 1.5A
OUT
f corresponding to on-time 2
Minimum off-time
•
•
345
400
250
470
350
kHz
ns
I
OUT
Diode Emulation Mode
Zero crossing threshold
DC value measured during test
-2
mV
Soft-Start
SS charge current
•
•
-14
1
-10
-6
µA
SS discharge current
Fault present
mA
VCC Linear Regulator
V
V
= 6V to 40V, I
= 0 to 30mA
•
•
4.8
5.0
4.7
5.2
V
V
IN
LOAD
V
CC
output voltage
= 5V, I
= 0 to 20mA
4.51
IN
LOAD
Power Good Output
Power good threshold
-10
1
-6.9
1.6
-5
4
ꢀ
ꢀ
Power good hysteresis
Power good sink current
mA
REV1A
3/16
XR76201
Electrical Characteristics (Continued)
Unless otherwise noted: T = 25°C, V = 24V, BST = V , SW = AGND = PGND = 0V, C = 4.7µF. Limits applying over
J
IN
CC
VCC
the full operating temperature range are denoted by a •.
Symbol
Parameter
Conditions
•
Min
Typ
Max
Units
Protection: OCP, OTP, Short-Circuit
Hiccup timeout
110
50
ms
µA
I
I
pin source current
45
-8
55
8
LIM
LIM
current temperature coefficient
0.4
0
ꢀ/°C
mV
ns
OCP comparator offset
Current limit blanking
•
•
•
GL rising > 1V
100
150
15
Thermal shutdown threshold(1)
Thermal hysteresis(1)
Rising temperature
°C
°C
VSCTH feedback pin short-circuit
threshold
Percent of V
, short-circuit is active
REF
50
60
70
ꢀ
after PGOOD is asserted
Output Power Stage
High-side MOSFET R
115
40
160
59
mΩ
mΩ
A
DSON
R
DSON
I
= 1A
DS
Low-side MOSFET R
DSON
I
Maximum output current
1.5A
OUT
V
= 24V, V
= 5V, I
= 5V, I
= 1.5A,
= 1.5A,
IN
OUT
OUT
OUT
100
110
°C
°C
f = 700kHz
Maximum ambient temperature at
continuous load
V
IN
= 12V, V
OUT
f = 600kHz
NOTE:
1. Guaranteed by design.
REV1A
4/16
XR76201
Pin Configuration, Top View
BST
30
SW PVIN PVIN PVIN PVIN PVIN PVIN
29
28
27
26
25
24
23
22 PVIN
21 PVIN
20 SW
ILIM
EN
1
2
3
4
5
6
7
PVIN PAD
TON
SS
19 PGND
18 PGND
PGOOD
FB
SW PAD
AGND PAD
PGND 17 PGND
PAD
16 PGND
AGND
15 PGND
8
9
10
11
12
SW
13
14
VIN
VCC AGND SW
SW
SW
Pin Functions
Pin Number
1
Pin Name
Type
Description
ILIM
EN/MODE
TON
A
Overcurrent protection programming. Connect with a resistor to SW.
Precision enable pin. Pulling this pin above 1.9V will turn the regulator on and it will operate in CCM.
If the voltage is raised above 3.0V then the regulator will operate in DCM/CCM depending on load.
2
3
4
5
6
I
A
A
Constant on-time programming pin. Connect with a resistor to AGND.
Soft-start pin. Connect an external capacitor between SS and AGND to program the soft-start rate
based on the 10uA internal source current.
SS
PGOOD
FB
O, OD
A
Power-good output. This open-drain output is pulled low when V
is outside the regulation.
OUT
Feedback input to feedback comparator. Connect with a set of resistors to VOUT and AGND in order
to program V
.
OUT
7, 10,
AGND Pad
AGND
A
Signal ground for control circuitry. Connect AGND Pad with a short trace to pins 7 and 10.
8
9
VIN
A
A
Supply input for the regulator’s LDO. Normally it is connected to PVIN.
VCC
The output of regulator’s LDO. For operation using a 5V rail, VCC should be shorted to VIN.
11-14, 20, 29,
SW Pad
Switch node. Drain of the low-side N-channel MOSFET. Source of the high-side MOSFET is wire-
bonded to the SW Pad. Pins 20 and 29 are internally connected to SW pad.
SW
PWR
PWR
15-19,
PGND Pad
Ground of the power stage. Should be connected to the system’s power ground plane. Source of the
low-side MOSFET is wire-bonded to PGND Pad.
PGND
21-28,
PVIN Pad
PVIN
BST
PWR
A
Input voltage for power stage. Drain of the high-side N-channel MOSFET.
30
High-side driver supply pin. Connect a bootstrap capacitor between BST and pin 29.
NOTE:
A = Analog, I = Input, O = Output, OD = Open Drain, PWR = Power.
REV1A
5/16
XR76201
Typical Performance Characteristics
Unless otherwise noted: V = 24V, V
= 3.3V, I
= 1.5A, f = 600kHz, T = 25°C. Application Circuit from the Application
IN
OUT
OUT
A
Information section.
3.340
3.330
3.320
3.310
3.300
3.290
3.280
3.270
3.260
3.340
3.330
3.320
3.310
3.300
3.290
3.280
3.270
3.260
5
10
15
20
25
30
35
40
0.0
0.2
0.4
0.6
0.8
(A)
1.0
1.2
1.4
I
V
(V)
OUT
IN
Figure 3.
Figure 4.
Load Regulation
Line Regulation
800
700
600
500
400
300
200
100
Calculated
Typical
900
700
500
300
100
Calculated
Typical
5
10
15
20
25
30
35
40
0
10
20
30
40
50
60
V
(V)
IN
R
(kΩ)
ON
Figure 5.
Figure 6.
t
vs. R
t
vs. V , R = 16.9k
ON IN ON
ON
ON
700
600
500
400
300
200
100
0
800
700
600
500
400
300
200
100
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
5
10
15
20
25
30
35
40
I
(A)
V
(V)
IN
OUT
Figure 7.
Figure 8.
frequency vs. I
frequency vs. V
OUT
IN
REV1A
6/16
XR76201
Typical Performance Characteristics (Continued)
Unless otherwise noted: V = 24V, V
= 3.3V, I
= 1.5A, f = 600kHz, T = 25°C. Application Circuit from the Application
IN
OUT
OUT
A
Information section.
2.2
2.0
1.8
1.6
1.4
1.2
1.0
70
60
50
40
30
0.8
1.0
1.2
1.4
(kΩ)
1.6
1.8
-40
-20
0
20
40
T (°C)
J
60
80
100
120
R
LIM
Figure 9.
Figure 10.
vs. temperature
I
vs. R
I
LIM
OCP
LIM
610
605
600
595
590
530
520
510
500
490
480
470
460
450
440
430
-40
-20
0
20
40
60
80
100
120
-40
-20
0
20
40
60
80
100
120
T (°C)
J
T (°C)
J
Figure 11.
vs. Temperature
Figure 12.
vs. Temperature, R = 35.7kΩ
V
REF
t
ON
ON
REV1A
7/16
XR76201
Typical Performance Characteristics (Continued)
Unless otherwise noted: V = 24V, V
= 3.3V, I
= 1.5A, f = 600kHz, T = 25°C. Application Circuit from the Application
IN
OUT
OUT
A
Information section.
SW
SW
V
OUT
AC-coupled 20MHz
24mVp-p
V
OUT
33mVp-p
AC-coupled 20MHz
IL
IL
400µs/div
2µs/div
Figure 13.
Figure 14.
Steady State, I
= 1.5A
Steady State, DCM, I
= 0A
OUT
OUT
V
V
IN
IN
EN
EN
V
V
OUT
OUT
IL
IL
4ms/div
4ms/div
Figure 15.
Figure 16.
Power Up, Forced CCM
Power Up, DCM/CCM
SW
SW
V
OUT
V
OUT
AC-coupled 20MHz
90mV
AC-coupled 20MHz
92mV
68mV
172mV
Di/Dt = 2.5A/µs
I
I
Di/Dt = 2.5A/µs
OUT
OUT
20µs/div
100µs/div
Figure 17.
Figure 18.
Load Step, Forced CCM, 0A-0.8A
Load Step, DCM/CCM, 0.05A-0.85A
REV1A
8/16
XR76201
Typical Performance Characteristics (Continued)
Efficiency
Unless otherwise noted: T
= 25°C, no air flow, L = 6.8µH, inductor losses are included, Application Circuit from the
AMBIENT
Application Information section.
100
95
100
95
90
85
80
75
70
65
60
55
50
800kHz
700kHz
600kHz
90
85
80
75
70
65
60
55
50
500kHz
400kHz
600kHz
400kHz
12.0V CCM
5.0V CCM
3.3V CCM
1.8V CCM
12.0V DCM
5.0V DCM
3.3V DCM
1.8V DCM
5.0V CCM
3.3V CCM
1.8V CCM
5.0V DCM
3.3V DCM
1.8V DCM
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5
(A)
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5
(A)
I
I
OUT
OUT
Figure 19.
Efficiency, V = 12V
Figure 20.
Efficiency, V = 24V
IN
IN
REV1A
9/16
XR76201
Functional Block Diagram
VCC
TON
BST
PVIN
V
UVLO
OTP
CC
Switching
Enabled
Enable LDO
4.25V
LDO
VIN
V
V
CC
CC
T
J
FB
0.6V
150 C
Current
PGOOD
Emulation &
V
IN
DC Correction
On Time
10µA
SS
FB
Switching
Enabled
Feedback
Comparator
0.6V
t
GH
GL
ON
R
S
Q
Q
Dead
Time
PGOOD Comparator
SW
V
CC
Minimum
On Time
Control
0.555V
Short-Circuit Detection
0.36V
Switching
Enabled
Enable
Hiccup
R
S
Q
Q
Hiccup
Mode
Enable LDO
Enable LDO
EN/MODE
If 4
1.9V
consecutive OCP
OCP
CCM or CCM/DCM
If 8 consecutive
ZCD then DCM
if 1 non-ZCD
Comparator
3V
50µA
then exit DCM
Zero Cross Detect
XR76201
SW
-2mV
AGND
ILIM
PGND
Figure 21. Functional Block Diagram
REV1A
10/16
XR76201
Applications Information
Functional Description
Selecting the DCM/CCM Mode
XR76201 is a synchronous step-down proprietary emulated
current-mode Constant On-Time (COT) regulators. The on-
In order to set the regulator operation to DCM/CCM,
a voltage between 3.1V and 5.5V must be applied to
EN/MODE pin. If an external control signal is available,
it can be directly connected to EN/MODE. In applications
where an external control is not available, EN/MODE input
time, which is programmed via R , is inversely proportional
ON
to V
and maintains a nearly constant frequency.
IN
The emulated current-mode control is stable with ceramic
output capacitors.
can be derived from V . If V is well regulated, use a
IN
IN
resistor divider and set the voltage to 4V. If V varies over
a wide range, the circuit shown in Figure 23 can be used to
generate the required voltage.
IN
Each switching cycle begins with GH signal turning on the
high-side (control) FET for a preprogrammed time. At the
end of the on-time, the high-side FET is turned off and
the low-side (synchronous) FET is turned on for a preset
minimum time (250ns nominal). This parameter is termed
minimum off-time. After the minimum off-time, the voltage at
the feedback pin FB is compared to an internal voltage ramp
V
IN
RZ
10k
at the feedback comparator. When V drops below the
FB
ramp voltage, the high-side FET is turned on and the cycle
repeats. This voltage ramp constitutes an emulated current
ramp and makes possible the use of ceramic capacitors,
in addition to other capacitor types, for output filtering.
R1
30.1k, 1%
Zener
MMSZ4685T1G or
Equivalent
Enable/Mode Input (EN/MODE)
EN/MODE pin accepts a tri-level signal that is used to
control turn on/off. It also selects between two modes of
operation: ‘forced CCM’ and ‘DCM/CCM’. If EN is pulled
below 1.8V, the regulator shuts down. A voltage between
2.0V and 2.8V selects the forced CCM mode which will run
the regulator in continuous conduction at all times. A voltage
higher than 3.1V selects the DCM/CCM mode which will run
the regulator in discontinuous conduction at light loads.
EN/MODE
R2
35.7k, 1%
Figure 22.
Selecting Forced CCM by Deriving EN/MODE from V
IN
Selecting the Forced CCM Mode
In order to set the regulator to operate in forced CCM,
a voltage between 2.0V and 2.8V must be applied to
EN/MODE. This can be achieved with an external
control signal that meets the above voltage requirement.
Where an external control is not available, the EN/MODE
V
IN
RZ
10k
can be derived from V . If V is well regulated, use a
IN
IN
resistor divider and set the voltage to 2.5V. If V varies
IN
over a wide range, the circuit shown in Figure 22 can be
V
EN
used to generate the required voltage. Note that at V
IN
of 5.5V and 40V the nominal Zever voltage is 4.0V and
5.0V respectively. Therefore for V in the range of 5.5V
EN/MODE
Zener
MMSZ4685T1G or
Equivalent
IN
to 40V, the circuit shown in Figure 22 will generate V
required for forced CCM.
EN
Figure 23.
Selecting DCM/CCM by Deriving EN/MODE from V
IN
REV1A
11/16
XR76201
Applications Information (Continued)
Programming the On-Time
Overcurrent Protection (OCP)
If load current exceeds the programmed overcurrent I ,
OCP
The on-time t is programmed via resistor R according
ON
ON
to following equation:
for four consecutive switching cycles, the module enters
hiccup mode of operation. In hiccup, the MOSFET gates
are turned off for 110ms (hiccup timeout). Following the
hiccup timeout, a soft-start is attempted. If OCP persists,
hiccup timeout will repeat. The module will remain in
hiccup mode until load current is reduced below the
V
× [t
ꢀ (2.5 × 10-8)]
IN
ON
3.05 x 10-10
vs. R , using the above equation, is
R
=
ON
A graph of t
ON
ON
compared to typical test data in Figure 5. The graph shows
that calculated data matches typical test data within 3ꢀ.
programmed I
. In order to program the overcurrent
OCP
protection, use the following equation:
The t
corresponding to a particular set of operating
ON
(I × 59mΩ) + 8mV
OCP
conditions can be calculated based on empirical data from:
R
=
LIM
I
LIM
V
OUT
t
=
where:
ON
V
× 0.97 x f
IN
ꢀ■
R
LIM
is resistor value for programming I
OCP
Where:
ꢀ■
I
is the overcurrent threshold to be
OCP
ꢀ■
f is the desired switching frequency at 1.5A
programmed
Substituting for t in the first equation we get:
ꢀ■
ꢀ■
ON
8mV is the OCP comparator maximum offset
I
is the internal current that generates
V
LIM
OUT
ꢀ
[(2.5 × 10-8) × V ]
IN
the necessary OCP comparator threshold
(use 45μA).
0.97 x f
R
=
ON
(3.05 × 10-10)
Note that I
has a positive temperature coefficient
LIM
Now R
conditions V , V
can be calculated in terms of operating
ON
of 0.4ꢀ/°C, Figure 10. This is meant to roughly match
and compensate for positive temperature coefficient of
the synchronous FET. The above equation is for worst-
case analysis and safeguards against premature OCP.
and f using the above equation.
IN
OUT
At V = 24V, I
= 1.5A we get the following R
:
IN
OUT
ON
Typical value of I
, for a given R , will be higher than
OCP
LIM
VOUT (V)
f (kHZ)
RON (kΩ)
that predicted by the above equation. Graph of calculated
vs. R is compared to typical I in Figure 9.
12
5
800
700
600
400
48.7
22.2
16.6
13.2
I
OCP
LIM
OCP
Short-Circuit Protection (SCP)
If the output voltage drops below 60ꢀ of its programmed
value, the module will enter hiccup mode. Hiccup will persist
until short-circuit is removed. SCP circuit becomes active
after PGOOD asserts high.
3.3
1.8
Over-Temperature (OTP)
OTP triggers at a nominal die temperature of 150°C.
The gate of switching FET and synchronous FET are
turned off. When die temperature cools down to 135°C,
soft-start is initiated and operation resumes.
Programming the Output Voltage
Use an external voltage divider as shown in the Application
Circuit to program the output voltage V
.
OUT
V
0.6V
OUT
R = R ×
ꢀ 1
1
2
where: R2 has a nominal value of 2kΩ
REV1A
12/16
XR76201
Applications Information (Continued)
Programming the Soft-Start
Maximum Allowable Voltage Ripple at FB Pin
Note that the steady-state voltage ripple at feedback pin
FB (V ) must not exceed 50mV in order for the
Place a capacitor CSS between the SS and AGND pins to
program the soft-start. In order to program a soft-start time
of TSS, calculate the required capacitance CSS from the
following equation:
FB,RIPPLE
regulator to function correctly. If V
is larger than
FB,RIPPLE
50mV then C
should be increased as necessary in order
OUT
to keep the V
below 50mV.
FB,RIPPLE
10µA
C
= t
SS SS
×
0.6V
Feed-Forward Resistor (R
)
FF
FETswitchingnoisemaycoupletoV
capacitance across the inductor, and to the FB pin via C .
throughtheparasitic
OUT
Feed-Forward Capacitor (C
)
FF
FF
A feed-forward capacitor (C ) may be necessary depending
Excessive noise at FB will cause poor load regulation.
FF
on the Equivalent Series Resistance (ESR) of C
. If only
OUT
To solve this problem place a resistor R
in series
FF
ceramic output capacitors are used for C
then a C
with C . R value up to 2ꢀ of R1 is acceptable.
OUT
FF
FF
FF
is necessary. Calculate C from:
FF
1
C
=
FF
2 ×
π
× R x 7 x f
1 LC
where:
ꢀ■
R1 is the resistor that is parallel with C
FF
ꢀ■
f
is calculated by the equation below:
LC
1
f
=
LC
2 x
π
x √ L x C
OUT
f
frequency must be less than 11kHz when using ceramic
LC
C . If necessary, increase L and/or C
OUT
in order to meet
OUT
this constraint
When using capacitors with higher ESR, such as
PANASONIC TPE series, a C is not required provided
FF
following conditions are met:
1.The frequency of output filter LC double-pole f
should be less than 11kHz
LC
2.The frequency of ESR Zero f
should be
ZERO,ESR
at least five times larger than f
LC
Note that if f
is less than 5 x f , then it is
LC
ZERO,ESR
recommended to set the f at less than 2kHz. C is still
LC
FF
not required.
REV1A
13/16
XR76201
Applications Information (Continued)
Application Circuit
C
0.1µF
BST
R4 2k
R3 18.2k
P
24V
IN
VIN
22
21
20
19
18
17
16
15
C
IN
4.7µF/50V
R
1.8k
LIM
1
2
3
4
5
6
7
PVIN
PVIN
SW
ILIM
EN
R
16.9k
ON
X
SW
TON
SS
C
47nf
PGND
PGND
PGND
PGND
PGND
SS
V
R5 10k
CC
FB
XR76201
PGOOD
FB
AGND
600kHz 3.3V at 0-1.5A
C
SW
Coilcraft XAL4030-682ME
6.8µH
C
0.1µf
IN1
OUT
47µF/10V
C
FF
P
VIN
R1 9.09k
270pF
V
CC
R
FF
20Ω
C
4.7µf
VCC
FB
R2 2k
Figure 24. Application Circuit
REV1A
14/16
XR76201
Package Description
REV1A
15/16
XR76201
Ordering Information(1)
Part Number
Operating Temperature Range
Lead-Free
Yes(2)
Package
QFN 5x5
Packaging Method
XR76201EL
Tray
XR76201ELTR
XR76201ELMTR
XR76201EVB
-40°C ≤ T ≤ 125°C
Tape and Reel
Mini Tape and Reel
J
XR76201 Evaluation Board
NOTE:
1. Refer to www.exar.com/XR76201 for most up-to-date Ordering Information.
2. Visit www.exar.com for additional information on Environmental Rating.
Revision History
Revision
1A
Date
Description
Sept 2016
Initial Release
www.exar.com
48760 Kato Road
Fremont, CA 94538
USA
Tel.: +1 (510) 668-7000
Fax: +1 (510) 668-7001
Email: powertechsupport@exar.com
Exar Corporation reserves the right to make changes to the products contained in this publication in order to improve design, performance or reliability. Exar Corporation conveys
no license under any patent or other right and makes no representation that the circuits are free of patent infringement. While the information in this publication has been
carefully checked, no responsibility, however, is assumed for inaccuracies.
Exar Corporation does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected
to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless Exar Corporation
receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the user assumes all such risks; (c) potential liability of
Exar Corporation is adequately protected under the circumstances.
Reproduction, in part or whole, without the prior written consent of Exar Corporation is prohibited. Exar, XR and the XR logo are registered trademarks of Exar Corporation.
All other trademarks are the property of their respective owners.
©2016 Exar Corporation
XR76201_DS_093016
REV1A
16/16
相关型号：
©2020 ICPDF网 联系我们和版权申明