XR76201
40V 1.5A Synchronous Step-Down COT Regulator
Description
FEATURES
■■ 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
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
■■ Precision enable and Power Good flag
■■ Programmable soft-start
■■ 30-pin 5mm x 5mm QFN package
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 ±10%, 18V to 36V, and
rectified 18VAC and 24VAC rails.
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
0.05% load and 0.15% 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.
A host of protection features, including overcurrent, over temperature,
short-circuit and UVLO, helps achieve safe operation under abnormal
operating conditions.
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
VIN
VIN
ENABLE/MODE
POWER GOOD
PVIN
3.330
CBST
EN/MODE
3.320
BST
PGOOD
VOUT
L1
SW
VCC
RPGOOD
SS
TON
CVCC
CSS
RON
AGND
XR76201
ILIM
RLIM
CFF
R1
FB
PGND
3.310
VOUT (V)
CIN
R2
COUT
3.300
3.290
3.280
3.270
3.260
Figure 1. Typical Application
5
10
15
20
25
VIN (V)
30
35
40
Figure 2. Line Regulation
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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.
PVIN.......................................................................5V to 40V
PVIN, VIN........................................................... -0.3V to 43V
PGOOD, VCC, TON, SS, EN, FB.................... -0.3V to 5.5V
VCC.................................................................. -0.3V to 6.0V
Switching frequency............................. 400kHz to 800kHz(3)
BST.................................................................-0.3V to 48V(1)
Junction temperature range.......................... -40°C to 125°C
BST-SW.............................................................. -0.3V to 6V
JEDEC51 package thermal resistance, θJA............. 28°C/W
SW, ILIM......................................................... -1V to 43V(1)(2)
Package power dissipation at 25°C.............................. 3.6W
VIN.........................................................................5V to 40V
SW, ILIM............................................................-1V to 40V(1)
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
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: TJ = 25°C, VIN = 24V, BST = VCC, SW = AGND = PGND = 0V, CVCC = 4.7µF. Limits applying over
the full operating temperature range are denoted by a •.
Symbol
Parameter
Conditions
•
Min
5.5
Typ
Max
Units
40
V
2
mA
Power Supply Characteristics
VIN
Input voltage range
VCC regulating
•
IVIN
VIN input supply current
Not switching, VIN = 24V, VFB = 0.7V
•
IVIN
VIN input supply current
f = 300kHz, RON = 215kΩ, VFB = 0.58V
12
mA
IOFF
Shutdown current
Enable = 0V, VIN = 12V
1
µA
0.7
Enable and Under-Voltage Lock-Out UVLO
VIH_EN_1
EN pin rising threshold
VEN_H_1
EN pin hysteresis
VIH_EN_2
EN pin rising threshold for DCM/CCM
operation
VEN_H_2
EN pin hysteresis
•
1.8
1.9
2.0
70
•
2.8
3.0
mV
3.1
100
VCC UVLO start threshold, rising edge
•
VCC UVLO hysteresis
4.00
4.25
230
REV1C
V
V
mV
4.40
V
mV
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XR76201
Electrical Characteristics (Continued)
Unless otherwise noted: TJ = 25°C, VIN = 24V, BST = VCC, SW = AGND = PGND = 0V, CVCC = 4.7µF. Limits applying over
the full operating temperature range are denoted by a •.
Symbol
Parameter
Conditions
•
Min
Typ
Max
Units
0.596
0.600
0.604
V
0.594
0.600
0.606
V
Reference Voltage
VREF
Reference voltage
VIN = 5.5V to 40V, VCC regulating
DC line regulation
CCM, closed loop, VIN = 5.5V to 40V, applies
to any COUT
±0.15
%
DC load regulation
CCM, closed loop, applies to any COUT
±0.05
%
•
Programmable Constant On-Time
tON1
On-time 1
RON = 6.04kΩ, VIN = 24V
•
85
100
117
ns
f corresponding to on-time 1
VOUT = 1.8V, VIN = 24V, RON = 6.04kΩ,
IOUT = 1.5A
•
710
830
980
kHz
tON(MIN)
Minimum programmable on-time
RON = 6.04kΩ, VIN = 24V
85
100
117
ns
tON2
On-time 2
RON = 14kΩ, VIN = 24V
•
174
205
236
ns
tON3
On-time 3
RON = 35.7kΩ, VIN = 24V
•
407
479
550
ns
f corresponding to on-time 2
VOUT = 1.8V, VIN = 24V, RON = 14kΩ,
IOUT = 1.5A
•
345
400
470
kHz
250
350
ns
Minimum off-time
•
Diode Emulation Mode
Zero crossing threshold
DC value measured during test
-2
mV
Soft-Start
SS charge current
SS discharge current
•
-14
-10
-6
µA
Fault present
•
1
VIN = 6V to 40V, ILOAD = 0 to 30mA
•
4.8
5.0
VIN = 5V, ILOAD = 0 to 20mA
•
4.51
4.7
-10
-6.9
-5
%
1.6
4
%
mA
VCC Linear Regulator
VCC output voltage
5.2
V
V
Power Good Output
Power good threshold
Power good hysteresis
Power good sink current
1
REV1C
mA
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XR76201
Electrical Characteristics (Continued)
Unless otherwise noted: TJ = 25°C, VIN = 24V, BST = VCC, SW = AGND = PGND = 0V, CVCC = 4.7µF. Limits applying over
the full operating temperature range are denoted by a •.
Symbol
Parameter
Conditions
•
Min
Typ
Max
Units
Protection: OCP, OTP, Short-Circuit
Hiccup timeout
110
ILIM pin source current
45
ILIM current temperature coefficient
50
ms
55
0.4
OCP comparator offset
•
-8
0
µA
%/°C
8
mV
Current limit blanking
GL rising > 1V
100
ns
Thermal shutdown threshold(1)
Rising temperature
150
°C
15
°C
Thermal hysteresis(1)
VSCTH feedback pin short-circuit
threshold
Percent of VREF, short-circuit is active
after PGOOD is asserted
•
50
60
70
%
115
160
mΩ
40
59
mΩ
Output Power Stage
RDSON
IOUT
High-side MOSFET RDSON
Low-side MOSFET RDSON
IDS = 1A
Maximum output current
Maximum ambient temperature at
continuous load
•
1.5A
A
VIN = 24V, VOUT = 5V, IOUT = 1.5A,
f = 700kHz
100
°C
VIN = 12V, VOUT = 5V, IOUT = 1.5A,
f = 600kHz
110
°C
NOTE:
1. Guaranteed by design.
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XR76201
Pin Configuration, Top View
BST
SW
PVIN
PVIN
PVIN
PVIN
PVIN
PVIN
30
29
28
27
26
25
24
23
22 PVIN
ILIM
1
EN
2
21 PVIN
TON
3
20 SW
SS
4
19 PGND
PGOOD
5
FB
6
AGND
7
PVIN PAD
18 PGND
SW PAD
AGND PAD
PGND 17 PGND
PAD
16 PGND
15 PGND
8
VIN
9
10
VCC AGND
11
12
13
14
SW
SW
SW
SW
Pin Functions
Pin Number
Pin Name
Type
Description
1
ILIM
A
Overcurrent protection programming. Connect with a resistor to SW.
2
EN/MODE
I
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.
3
TON
A
Constant on-time programming pin. Connect with a resistor to AGND.
4
SS
A
Soft-start pin. Connect an external capacitor between SS and AGND to program the soft-start rate
based on the 10µA internal source current.
5
PGOOD
O, OD
6
FB
A
Feedback input to feedback comparator. Connect with a set of resistors to VOUT and AGND in order
to program VOUT.
7, 10,
AGND Pad
AGND
A
Signal ground for control circuitry. Connect AGND Pad with a short trace to pins 7 and 10.
8
VIN
A
Supply input for the regulator’s LDO. Normally it is connected to PVIN.
9
VCC
A
The output of regulator’s LDO. For operation using a 5V rail, VCC should be shorted to VIN.
11-14, 20, 29,
SW Pad
SW
PWR
Switch node. The drain of the low-side N-channel MOSFET. The source of the high-side MOSFET is
wire-bonded to the SW Pad. Pins 20 and 29 are internally connected to SW pad.
15-19,
PGND Pad
PGND
PWR
Ground of the power stage. Should be connected to the system’s power ground plane. The source of
the low-side MOSFET is wire-bonded to PGND Pad.
21-28,
PVIN Pad
PVIN
PWR
Input voltage for power stage. The drain of the high-side N-channel MOSFET.
30
BST
A
Power-good output. This open-drain output is pulled low when VOUT is outside the regulation.
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.
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XR76201
Typical Performance Characteristics
3.340
3.340
3.330
3.330
3.320
3.320
3.310
3.310
VOUT (V)
VOUT (V)
Unless otherwise noted: VIN = 24V, VOUT = 3.3V, IOUT = 1.5A, f = 600kHz, TA = 25°C. The application circuit is from the
Application Information section.
3.300
3.290
3.300
3.290
3.280
3.280
3.270
3.270
3.260
0.0
0.2
0.4
0.6
0.8
IOUT (A)
1.0
1.2
3.260
1.4
5
10
15
20
25
30
35
40
VIN (V)
Figure 3.
Load Regulation
Figure 4.
Line Regulation
800
Calculated
Typical
700
Calculated
Typical
900
600
700
tON (ns)
tON (ns)
500
400
500
300
300
200
100
100
0
10
20
30
40
50
60
5
10
15
20
RON (kΩ)
Figure 5.
tON vs. RON
800
600
700
35
40
35
40
600
500
500
f (kHz)
400
f (kHz)
30
Figure 6.
tON vs. VIN, RON = 16.9kΩ
700
300
200
400
300
200
100
0
25
VIN (V)
100
0
0.2
0.4
0.6
0.8
IOUT (A)
1
1.2
0
1.4
5
10
15
20
25
30
VIN (V)
Figure 7.
Frequency vs. IOUT
Figure 8.
Frequency vs. VIN
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XR76201
Typical Performance Characteristics (Continued)
Unless otherwise noted: VIN = 24V, VOUT = 3.3V, IOUT = 1.5A, f = 600kHz, TA = 25°C. The application circuit is from the
Application Information section.
2.2
70
2.0
60
ILIM (μA)
IOCP (A)
1.8
1.6
1.4
50
40
1.2
1.0
1.0
0.8
1.2
1.4
RLIM (kΩ)
1.6
30
1.8
-40
-20
0
Figure 9.
IOCP vs. RLIM
20
40
TJ (°C)
60
80
100
120
100
120
Figure 10.
ILIM vs. Temperature
610
530
520
510
500
490
600
tON (ns)
VREF (mV)
605
595
480
470
460
450
440
590
-40
-20
0
20
40
TJ (°C)
60
80
100
430
120
-40
Figure 11.
VREF vs. Temperature
-20
0
20
40
TJ (°C)
60
80
Figure 12.
tON vs. Temperature, RON = 35.7kΩ
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XR76201
Typical Performance Characteristics (Continued)
Unless otherwise noted: VIN = 24V, VOUT = 3.3V, IOUT = 1.5A, f = 600kHz, TA = 25°C. The application circuit is from the
Application Information section.
SW
SW
VOUT
AC-coupled 20MHz
VOUT
AC-coupled 20MHz
33mVp-p
24mVp-p
IL
IL
2µs/div
400µs/div
Figure 13.
Steady State, IOUT = 1.5A
Figure 14.
Steady State, DCM, IOUT = 0A
VIN
VIN
EN
EN
VOUT
VOUT
IL
IL
4ms/div
4ms/div
Figure 15.
Power Up, Forced CCM
Figure 16.
Power Up, DCM / CCM
SW
SW
VOUT
AC-coupled 20MHz
VOUT
AC-coupled 20MHz
90mV
68mV
92mV
172mV
Di/Dt = 2.5A/µs
IOUT
IOUT
Di/Dt = 2.5A/µs
20µs/div
100µs/div
Figure 17.
Load Step, Forced CCM, 0A - 0.8A
Figure 18.
Load Step, DCM / CCM, 0.05A - 0.85A
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XR76201
Typical Performance Characteristics (Continued)
Efficiency
Unless otherwise noted: TAMBIENT = 25°C, no air flow, L = 6.8µH, inductor losses are included, application circuit is from
the Application Information section.
100
100
95
600kHz
90
90
500kHz
85
400kHz
Efficiency (%)
Efficiency (%)
85
95
80
75
70
65
60
55
5.0V DCM
3.3V DCM
1.8V DCM
700kHz
80
600kHz
400kHz
75
70
65
60
5.0V CCM
3.3V CCM
1.8V CCM
800kHz
55
12.0V DCM
5.0V DCM
3.3V DCM
1.8V DCM
12.0V CCM
5.0V CCM
3.3V CCM
1.8V CCM
50
50
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
IOUT (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
IOUT (A)
Figure 19.
Efficiency, VIN = 12V
Figure 20.
Efficiency, VIN = 24V
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XR76201
Functional Block Diagram
VCC
TON
VCC UVLO
Enable LDO
VIN
LDO
VCC
OTP
TJ
PVIN
Switching
Enabled
4.25V
VCC
BST
FB
0.6V
150 C
PGOOD
10µA
Current
Emulation &
DC Correction
VIN
On Time
SS
Switching
Enabled
FB
Feedback
Comparator
0.6V
R Q
S Q
PGOOD Comparator
tON
Dead
Time
Control
Minimum
On Time
0.555V
Short-Circuit Detection
0.36V
Switching
Enabled
GH
GL
Enable
Hiccup
R Q
S Q
Hiccup
Mode
Enable LDO
Enable LDO
EN/MODE
If 4
consecutive OCP
1.9V
CCM or CCM/DCM
3V
Zero Cross Detect
SW
VCC
If 8 consecutive
ZCD then DCM
if 1 non-ZCD
then exit DCM
OCP
Comparator
50µA
XR76201
SW
-2mV
AGND
ILIM
PGND
Figure 21. Functional Block Diagram
REV1C
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XR76201
Applications Information
Functional Description
XR76201 is a synchronous step-down, proprietary emulated
current-mode Constant On-Time (COT) regulator. The ontime, which is programmed via RON, is inversely proportional
to VIN and maintains a nearly constant frequency.
The emulated current-mode control is stable with ceramic
output capacitors.
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 lowside (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
at the feedback comparator. When VFB drops below the
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.
Selecting the DCM / CCM Mode
In order to set the regulator operation to DCM / CCM,
a voltage between 3.1V and 5.5V must be applied to the
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, the EN/MODE
input can be derived from VIN. If VIN is well regulated, use a
resistor divider and set the voltage to 4V. If VIN varies over
a wide range, the circuit shown in Figure 23 can be used to
generate the required voltage.
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/MODE 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.
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
can be derived from VIN. If VIN is well regulated, use a
resistor divider and set the voltage to 2.5V. If VIN varies
over a wide range, the circuit shown in Figure 22 can be
used to generate the required voltage. Note that at VIN
of 5.5V and 40V, the nominal Zever voltage is 4.0V and
5.0V respectively. Therefore for VIN in the range of 5.5V to
40V, the circuit shown in Figure 22 will generate the VEN
required for Forced CCM.
VIN
RZ
10k
R1
30.1k, 1%
Zener
MMSZ4685T1G or
Equivalent
EN/MODE
R2
35.7k, 1%
Figure 22.
Selecting Forced CCM by Deriving EN/MODE from VIN
VIN
RZ
10k
VEN
Zener
MMSZ4685T1G or
Equivalent
EN/MODE
Figure 23.
Selecting DCM/CCM by Deriving EN/MODE from VIN
REV1C
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XR76201
Applications Information (Continued)
Programming the On-Time
The on-time tON is programmed via resistor RON according
to following equation:
where:
■■ RLIM
RON =
is the
programmed
3.05 x 10-10
A graph of tON vs. RON, using the above equation, is
VINdata
× [tON
(2.5 × 5.
10-8The
)] graph shows
compared to typical test
in –Figure
R
=
ON matches
that calculated data
typical
test
data
within 3%.
VOUT
3.05 x 10-10
tON =
The tON corresponding
a particular
VIN
–x(2.5
)] of operating
VIN×to×[tON
0.97
f × 10-8set
=
ONcalculated
conditions can Rbe
based -10
on empirical data from:
3.05 x 10
VOUT
tON
=
VOUT
VIN
× 0.97
x f-8) × VIN]
– [(2.5
× 10
0.97 x f
VOUT
Where: RON = tON = (3.05 × 10-10)
VIN × 0.97 x f
■■ f is the desired switching
frequency at 1.5A
VOUT
–
[(2.5
× 10-8) × V ]
Substituting for tON0.97
in the
x f first equation weINget:
RON = (IOCP × 59mΩ) + -10
8mV
RLIM = VOUT(3.05 × 10 ) -8
I – [(2.5 × 10 ) × VIN]
0.97 x f LIM
RON =
(3.05 × 10-10)
(IOCP × 59mΩ) + 8mV
Now RON Rcan
LIM =be calculated in terms of operating
ILIMfV using the above equation.
conditions VIN, VOUT, and
R1 = R2 × OUT – 1
8mVfollowing RON:
× 59mΩ)
At VIN = 24V, IOUT (I=OCP
1.5A
we 0.6V
get+ the
RLIM =
ILIM
VOUT (V)
12
5
3.3
f (kHZ)
V
OUT – 1 RON (kΩ)
0.6V
800 10µA
48.7
CSS = tSS ×
0.6V
VOUT
22.2
–1
R1 = R2 × 700
0.6V
R1 = R2 ×
600
16.6
is resistor value for programming IOCP
■■ IOCP
VIN × [tON – (2.5 × 10 )]
-8
10µA
CSS = tSS
×
1.8
400
13.2
1 0.6V
CFF =
x 7 x fLC
2 × π × R110µA
CSS(OCP)
= tSS ×
Overcurrent Protection
0.6V
If load current exceeds the programmed overcurrent IOCP
1
for four consecutive
cycles,
the module enters the
CFFswitching
=
π ×hiccup,
R1 x 7 x the
fLC MOSFET gates
2 × In
hiccup mode of operation.
are turned off for 110ms (hiccup timeout). Following the
11
hiccup timeout, afCLC
soft-start
If OCP persists,
FF
== 2 × πis×attempted.
R1 x 7 x fLC
the hiccup timeout will2 repeat.
x π x √ L xThe
COUTmodule will remain
in hiccup mode until load current is reduced below the
programmed IOCP. In order to program the overcurrent
1
protection, use thefLC
following
equation:
=
2 x π x √ L x COUT
(IOCP × 59mΩ) + 8mV
RLIM =
1
fLC =
ILIM
2 x π x √ L x COUT
■■ 8mV
overcurrent
threshold
to
be
is the OCP comparator maximum offset
■■ ILIM
is the internal current that generates
the necessary OCP comparator threshold
(use 45μA).
Note that ILIM has a positive temperature coefficient
of 0.4%/°C, Figure 10. This is meant to roughly match
and compensate for positive temperature
coefficient of
VIN × [tON – (2.5 × 10-8)]
the synchronous
FET.
The
above
equation
is for worstRON =
-10
case analysis and safeguards
premature OCP.
3.05 x 10against
Typical value of IOCP, for a given RLIM, will be higher than
that predicted by the above equation. A graph of calculated
IOCP vs. RLIM is compared to typical IOCP in Figure 9.
VOUT
tON = (SCP)
Short-Circuit Protection
VIN × 0.97 x f
If the output voltage drops below 60% of its programmed
value, the module will enter hiccup mode. Hiccup will persist
until short-circuit is removed. The SCP circuit becomes
VOUT
active after PGOOD
asserts high. -8
– [(2.5 × 10 ) × VIN]
0.97 x f
R
=
Over-Temperature
(OTP)
ON
(3.05 × 10-10)
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
operation
resumes.
(I and
× 59mΩ)
+ 8mV
RLIM = OCP
ILIM
Programming the Output Voltage
Use an external voltage divider as shown in the Application
Circuit to program the output voltage VOUT.
R1 = R2 ×
VOUT
–1
0.6V
where: R2 has a nominal value of 2kΩ
Programming the Soft-Start
10µA
Place a capacitor C
CSS
tSS × the SS and AGND pins to
SS =between
program the soft-start. In order 0.6V
to program a soft-start time
of tSS, calculate the required capacitance CSS from the
following equation:
1 10µA
SS2 ×= πtSS
× R×1 x 0.6V
7 x fLC
CFF =C
fLC =
REV1C
1
2 x π x √ L x COUT
12/17
ILIM
V
R1 = R2 × OUT
VOUT– 1
–1
R1 = R2 × 0.6V
0.6V
XR76201
Applications Information (Continued)
Feed-Forward Capacitor (CFF)10µA
CSS = tSS
× ) may
10µA
A feed-forward capacitor
FF
CSS =(C
tSS
× 0.6V be necessary depending
0.6V (ESR) of COUT. If only
on the Equivalent Series Resistance
ceramic output capacitors are used for COUT, then a CFF
is necessary. Calculate CFF from:
11
CFFC = =
FF 2 ×2 ×
π π× ×R1R1x x7 7x xfLCfLC
Feed-Forward Resistor (RFF)
FET switching noise may couple to VOUT through the parasitic
capacitance across the inductor and to the FB pin via CFF.
Excessive noise at FB will cause poor load regulation.
To solve this problem, place a resistor RFF in series
with CFF. An RFF value up to 2% of R1 is acceptable.
where:
■■ R1
is the resistor that is parallel with CFF
■■ fLC
is calculated by the equation below:
fLCfLC
==
Maximum Allowable Voltage Ripple at FB Pin
Note that the steady-state voltage ripple at feedback pin
FB (VFB,RIPPLE) must not exceed 50mV in order for the
regulator to function correctly. If VFB,RIPPLE is larger than
50mV, then COUT should be increased as necessary in
order to keep the VFB,RIPPLE below 50mV.
11
COUT
2 x2 πx π
x √x √L Lx xCOUT
The fLC frequency must be less than 11kHz when using
ceramic COUT. If necessary, increase L and / or COUT in
order to meet this constraint.
When using capacitors with higher ESR such as the
PANASONIC TPE series, a CFF is not required provided
following conditions are met:
1. The frequency of output filter LC double-pole fLC
should be less than 11kHz
2. The frequency of ESR Zero fZERO,ESR should be
at least five times larger than fLC
Note that if fZERO,ESR is less than 5 x fLC, then it is
recommended to set the fLC at less than 2kHz. CFF is still
not required.
REV1C
13/17
XR76201
Applications Information (Continued)
Application Circuit
R3 18.2k
24VIN
34
33
32
31
30
29
28
27
26
25
24
23
PVIN
RON 16.9k
CSS 47nf
VCC
FB
R5 10k
1
2
3
4
5
6
7
ILIM
EN
TON
SS
PGOOD
FB
AGND
XR76201
VIN
VCC
AGND
SW
SW
SW
SW
RLIM 1.8k
8
9
10
11
12
13
14
SW
PVIN PAD
SW PAD
PGND PAD
AGND PAD
BST
SW
PVIN
PVIN
PVIN
PVIN
PVIN
PVIN
R4 2k
SW
CBST 0.1µF
PVIN
PVIN
SW
PGND
PGND
PGND
PGND
PGND
22
21
20
X
19
18
17
16
15
CIN
4.7µF/50V
600kHz 3.3V at 0-1.5A
SW
Coilcraft XAL4030-682ME
6.8µH
CIN1
0.1µf
PVIN
VCC
CFF
270pF
R1 9.09k
COUT
47µF/10V
RFF
20Ω
CVCC
4.7µf
FB
R2 2k
Figure 24. Application Circuit
REV1C
14/17
XR76201
Mechanical Dimensions
(0.615)
(0.615)
D
A
B
D1
D3
(0.610)
14
8
15
E3
E1
7
L
13x
1
22
aaa C 2x
bbb
ddd
TOP VIEW
30X
23
Nx b
C A B
C
(0.325)
13x
30(N)
E2
aaa C 2x
e
E
PIN #1
INDEX AREA
D2
BOTTOM VIEW
A3
A
A1
SIDE VIEW
Dimension Table
Th
Sy
ick
mb
ol
ne
A
A1
A3
b
D
E
e
D1
E1
D2
E2
D3
E3
L
aaa
bbb
ccc
ddd
eee
N
ss MINIMUM NOMINAL MAXIMUM
0.80
0.90
1.00
0.00
0.02
0.20 Ref.
0.25
5.00 BSC
5.00 BSC
0.50 BSC
1.720
2.785
2.785
1.285
1.495
2.053
0.40
0.05
0.10
0.10
0.05
0.08
30
0.05
0.18
1.570
2.635
2.635
1.135
1.345
1.903
0.30
0.30
1.820
2.885
2.885
1.385
1.595
2.153
0.50
TERMINAL DETAIL
Drawing No.: POD-00000018
Revision: B
REV1C
15/17
XR76201
Recommended Land Pattern and Stencil
TYPICAL RECOMMENDED LAND PATTERN
TYPICAL RECOMMENDED STENCIL
Drawing No.: POD-00000018
Revision: B
REV1C
16/17
XR76201
Ordering Information(1)
Part Number
Operating Temperature Range
Package
Packaging Method
Lead-Free
XR76201ELTR
-40°C ≤ TJ ≤ 125°C
QFN 5x5
Tape and Reel
Yes(2)
XR76201EVB
XR76201 Evaluation Board
NOTE:
1. Refer to www.maxlinear.com/XR76201 for most up-to-date Ordering Information.
2. Visit www.maxlinear.com for additional information on Environmental Rating.
Revision History
Revision
Date
Description
1A
Sept 2016
Initial Release
1B
June 2018
Update to MaxLinear logo. Update format and Ordering Information.
1C
October 2019
Correct block diagram by changing the input gate into the Hiccup Mode from an AND gate to
an OR gate. Update ordering information. Add recommended land pattern and stencil.
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5966 La Place Court
Suite 100
Carlsbad, CA 92008
Tel.:+1 (760) 692-0711
Fax: +1 (760) 444-8598
www.maxlinear.com
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