Altera EN5311QI 1a powersoc synchronous buck regulator with integrated inductor Datasheet

Enpirion® Power Datasheet
EN5311QI 1A PowerSoC
Synchronous Buck Regulator
With Integrated Inductor
Product Overview
Featuring Integrated Inductor Technology
VIN
The Ultra-Low-Profile EN5311QI is targeted to
applications where board area and profile are
critical. EN5311QI is a complete power
conversion solution requiring only two low cost
ceramic MLCC caps. Inductor, MOSFETS,
PWM, and compensation are integrated into a
tiny 5mm x 4mm x 1.1mm QFN package. The
EN5311QI is engineered to simplify design and
to minimize layout constraints.
4 MHz
switching frequency and internal type III
compensation provides superior transient
response.
With a 1.1 mm profile, the
EN5311QI is ideal for space and height
constrained applications.
UVLO
Thermal Limit
Current Limit
ENABLE
Soft Start
P-Drive
(-)
Logic
VOUT
PWM
Comp
(+)
N-Drive
GND
VSENSE
Sawtooth
Generator
Compensation
Network
(-)
Switch
Error
Amp
VFB
(+)
DAC
VREF
Voltage
Select
A 3-pin VID output voltage selector provides
seven pre-programmed output voltages along
with an option for external resistor divider.
Output voltage can be programmed on-the-fly
to provide fast, dynamic voltage scaling.
Package Boundry
VS0 VS1 VS2
Product Highlights
Typical Application Circuit
• Revolutionary Integrated Inductor
• 5mm x 4mm x1.1mm QFN package
• Very small total solution foot print*
• 4 MHz switching frequency
• Only two low cost MLCC caps required
• Designed for low noise/low EMI
• Very low ripple voltage; 5mVp-p Typical
• High efficiency, up to 95%
• Wide 2.4V to 6.6V input range
• 1000mA continuous output current
• Less than 1 µA standby current.
• Excellent transient performance
• 3 Pin VID Output Voltage select
• External divider: 0.6V to VIN-Vdropout
• 100% duty cycle capable
• Short circuit and over current protection
• UVLO and thermal protection
• RoHS compliant; MSL 3 260°C reflow
Voltage
Select
VS0
VS1
VS2
EN5311QI
Vin
4.7µF
VOUT
Vout
VFB
10µF
GND
Figure 1. Typical application circuit.
Applications
•
•
•
•
•
•
•
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VSense
ENABLE
VIN
October 11, 2013
Area constrained applications
Noise Sensitive Applications such as A/V
and RF
LDO replacement for improved thermals
Set top box/home gateway
Smart phones, PDAs
VoIP and Video phones
Personal Media Players
www.altera.com/enpirion
Rev E
EN5311QI
Pin
Description
other or to any external signal, voltage, or
ground. One or more of these pins may be
connected internally.
VSENSE (Pin 15):
Sense pin for output
voltage regulation.
Connect VSENSE to the
output voltage rail as close to the terminal of
the output filter capacitor as possible.
VFB (Pin 16): Feed back pin for external
divider option. When using the external divider
option (VS0=VS1=VS2= high) connect this pin
to the center of the external divider. Set the
divider such that VFB = 0.603V.
VS0,VS1,VS2 (Pin 17,18,19): Output voltage
select. VS0=pin19, VS1=pin18, VS2=pin17.
Selects one of seven preset output voltages or
choose external divider by connecting pins to
logic high or low. Logic low is defined as VLOW
≤ 0.4V. Logic high is defined as VHIGH ≥ 1.4V.
Any level between these two values is
indeterminate.
Figure 2. Pin description, top view.
VIN (Pin 1,2): Input voltage pin.
power to the IC.
Supplies
Input GND: (Pin 3): Input power ground.
Connect this pin to the ground terminal of the
input
capacitor.
Refer
to
Layout
Recommendations for further details.
ENABLE (Pin 20): Output enable. Enable =
logic high, disable = logic low. Logic low is
defined as VLOW ≤ 0.2V. Logic high is defined
as VHIGH ≥ 1.4V. Any level between these two
values is indeterminate.
Output GND: (Pin 4): Power ground. The
output filter capacitor should be connected
between this pin and VOUT . Refer to Layout
recommendations for further detail.
Bottom Thermal Pad: Device thermal pad to
remove heat from package. Connect to PCB
surface ground pad and PCB internal ground
plane (see layout recommendations).
VOUT (Pin 5,6,7): Regulated output voltage.
NC (Pin 8,9,10,11,12,13,14): These pins
should not be electrically connected to each
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Functional Block Diagram
VIN
UVLO
Thermal Limit
Current Limit
ENABLE
Soft Start
P-Drive
(-)
Logic
VOUT
PWM
Comp
(+)
N-Drive
GND
VSENSE
Sawtooth
Generator
Compensation
Network
(-)
Switch
Error
Amp
VFB
(+)
DAC
Voltage
Select
VREF
Package Boundry
VS0 VS1 VS2
Figure 3. Functional Block Diagram.
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Absolute Maximum Ratings
CAUTION: Absolute Maximum ratings are stress ratings only. Functional operation beyond
recommended operating conditions is not implied. Stress beyond absolute maximum ratings may
cause permanent damage to the device. Exposure to absolute maximum rated conditions for
extended periods may affect device reliability.
PARAMETER
SYMBOL
MIN
MAX
UNITS
VIN
-0.3
-0.3
-0.3
-65
7.0
VIN + 0.3
2.7
150
260
2000
V
V
V
°C
°C
V
Input Supply Voltage
Voltages on: ENABLE, VSENSE, VS0-VS2
Voltage on: VFB
Storage Temperature Range
Reflow Temp, 10 Sec, MSL3 JEDEC J-STD-020A
ESD Rating (based on Human Body Model)
TSTG
Recommended Operating Conditions
PARAMETER
SYMBOL
Input Voltage Range (VID)
VIN
Input Voltage Range (External Divider (VFB))1
VIN
Output Voltage Range
VOUT
Output Current
IOUT
Operating Ambient Temperature
TA
Operating Junction Temperature
TJ
1. See Section “Application Information” for specific circuit requirements
MIN
MAX
UNITS
2.4
2.4
0.6
0
-40
-40
5.5
6.6
VIN-0.6
1000
+85
+125
V
V
V
mA
°C
°C
Thermal Characteristics
PARAMETER
SYMBOL
θJA
θJC
TJ-TP
Thermal Resistance: Junction to Ambient (0 LFM)
Thermal Resistance: Junction to Case (0 LFM)
Thermal Shutdown
Thermal Shutdown Hysteresis
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TYP
UNITS
65
15
+150
15
°C/W
°C/W
°C
°C
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Electrical Characteristics
NOTE: TA = 25°C unless otherwise noted. Typical values are at V IN = 3.6V, CIN = 4.7µF, COUT=10uF.
NOTE: VIN must be greater than VOUT + 0.6V.
PARAMETER
Operating Input Voltage
SYMBOL
Under Voltage Lockout
UVLO Hysteresis
VUVLO
VOUT Initial Accuracy (VID)
VIN
VOUT
VOUT Variation for all
Causes (VID)
VOUT
Feedback Pin Voltage
VFB
Feedback Pin Voltage
VFB
Feedback Pin Input Current
Dynamic Voltage Slew
Rate†
Output Current
Shut-Down Current
Quiescent Current
IFB
TEST CONDITIONS
Using VID
Using External Divider (VFB)1
VIN going low to high
2.4V ≤ VIN ≤ 5.5V, ILOAD = 100mA;
TA = 25C
2.4V ≤ VIN ≤ 5.5V, ILOAD = 0 - 1A,
TA = -40°C to +85°C
2.4V ≤ VIN ≤ 6.6V, ILOAD = 100mA
TA = 25C; VSO=VS1=VS2=1
2.4V ≤ VIN ≤ 6.6V, ILOAD = 0 - 1A,
TA = -40°C to +85°C;
VSO=VS1=VS2=1
PFET OCP Threshold
ILIM
VS0-VS1 Thresholds
VTH
VS0-VS2 Pin Input Current
IVSX
Enable Voltage Threshold
TYP
MAX
5.5
6.6
2.3
UNITS
V
V
V
V
-2.0
+2.0
%
-3.0
+3.0
%
2.2
0.145
0.591
0.603
0.615
0.585
0.603
0.621
1
Vslew
IOUT
ISD
MIN
2.4
2.4
1.24
1.65
1.4
2.1
mA
µA
µA
2
A
0.0
1.4
0.4
VIN
0.0
1.4
Enable Pin Input Current
IEN
Operating Frequency
FOSC
PFET On Resistance
RDS(ON)
NFET On Resistance
RDS(ON)
Typical inductor DCR
Soft-Start Operation
VOUT Soft Start Slew Rate†
∆VSS
VID Mode 2
1.24
Soft Start Rise Time
VFB mode 2
0.80
∆TSS
1. See Section “Application Information” for specific circuit requirements
2. Measured from when VIN ≥ VUVLO & ENABLE pin crosses its logic High threshold
V/mS
0.75
800
1
Logic Low
Logic High
VIN = 3.6V
V
nA
1000
Enable = Low
No switching
2.4V ≤ VIN ≤ 6.6V,
0.6V ≤ VOUT ≤ VIN – 0.6V
Pin = Low
Pin = High
V
nA
0.2
VIN
µA
MHz
mΩ
mΩ
Ω
2
4
340
270
.110
1.65
1.10
V
2.1
1.40
V/mS
mS
† Parameter guaranteed by design.
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Typical Performance Characteristics
Efficiency Vs. Load Current (Vin = 3.3V)
95
100
90
95
Efficency (%)
Efficency (%)
Efficiency Vs. Load Current (Vin = 5.0V)
85
80
75
70
65
60
55
85
80
75
70
65
60
55
50
50
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0
Load Current (A)
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Load Current (A)
Top to Bottom: V OUT = 3.3 V, 2.5 V, 1.8 V, 1.5 V, 1.2 V, 0.8 V
Top to Bottom: V OUT = 2.5 V, 1.8 V, 1.5 V, 1.2 V, 0.8 V
Output Ripple: V IN = 5.0 V
Output Ripple: V IN = 3.3 V
VOUT = 1.2V, I LOAD = 1A, C OUT = 1 x 10µF 0805
VOUT = 1.2V, I LOAD = 1A, C OUT = 1 x 10µF 0805
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Detailed Description
Protection features include under-voltage lockout (UVLO), over-current protection (OCP),
short circuit protection, and thermal overload
protection.
Functional Overview
The EN5311QI is a complete DCDC converter
solution requiring only two low cost MLCC
capacitors.
MOSFET switches, PWM
controller, Gate-drive, compensation, and
inductor are integrated into the tiny 5mm x
4mm x 1.1mm package to provide the smallest
footprint possible while maintaining high
efficiency, low ripple, and high performance.
The converter uses voltage mode control to
provide the simplest implementation and high
noise immunity. The device operates at a high
switching frequency. The high switching
frequency allows for a wide control loop
bandwidth
providing
excellent
transient
performance. The high switching frequency
enables the use of very small components
making possible this unprecedented level of
integration.
Integrated Inductor
Altera has introduced the world’s first product
family featuring integrated inductors. The use
of an internal inductor localizes the noises
associated with the output loop currents. The
inherent shielding and compact construction of
the integrated inductor reduces the radiated
noise that couples into the traces of the circuit
board.
Further, the package layout is
optimized to reduce the electrical path length
for the AC ripple currents that are a major
source of radiated emissions from DCDC
converters.
The
integrated
inductor
significantly reduces parasitic effects that can
harm loop stability, and makes layout very
simple.
Altera Enpirion’s proprietary power MOSFET
technology provides very low switching loss at
frequencies of 4 MHz and higher, allowing for
the use of very small internal components, and
very wide control loop bandwidth.
Unique
magnetic design allows for integration of the
inductor into the very low profile 1.1mm
package. Integration of the inductor virtually
eliminates the design/layout issues normally
associated
with
switch-mode
DCDC
converters. All of this enables much easier
and faster integration into various applications
to meet demanding EMI requirements.
Soft Start
Internal soft start circuits limit in-rush current
when the device starts up from a power down
condition or when the “ENABLE” pin is
asserted “high”. Digital control circuitry limits
the VOUT ramp rate to levels that are safe for
the Power MOSFETS and the integrated
inductor.
The EN5311QI operates in a constant slew
rate when the output voltage is programmed
with an internal VID code. The EN5311QI,
when in external resistor divider mode, has a
constant start up time. Please refer to the
Electrical Characteristics table for soft-start
slew rates and soft-start time
Output voltage is chosen from seven preset
values via a three pin VID voltage select
scheme. An external divider option enables
the selection of any voltage in the 0.6V to VIN0.6V range. This reduces the number of
components that must be qualified and
reduces inventory burden. The VID pins can
be toggled on the fly to implement glitch free
dynamic voltage scaling.
Excess bulk capacitance on the output of the
device can cause an over-current condition at
startup.
Assuming no-load at startup, the
maximum total capacitance on the output,
including the output filter capacitor, bulk and
decoupling capacitance, at the load, is given
as:
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EN5311QI
the voltage drops below the UVLO threshold
the lockout circuitry will again disable the
switching. Hysteresis is included to prevent
chattering between states.
In VID Mode:
COUT_TOTAL_MAX = COUT_Filter + COUT_BULK = 700uF
In external divider mode:
Enable
COUT_TOTAL_MAX = 1.22x10-3/VOUT Farads
The ENABLE pin provides a means to shut
down the converter or enable normal
operation. A logic low will disable the converter
and cause it to shut down. A logic high will
enable the converter into normal operation. In
shutdown mode, the device quiescent current
will be less than 1 uA.
The nominal value for COUT is 10uF. See the
applications section for more details.
Over Current/Short Circuit Protection
The current limit function is achieved by
sensing the current flowing through a sense PMOSFET which is compared to a reference
current. When this level is exceeded the PFET is turned off and the N-FET is turned on,
pulling VOUT low. This condition is maintained
for a period of 1mS and then a normal soft start
is initiated. If the over current condition still
persists, this cycle will repeat in a “hick-up”
mode.
NOTE: This pin must not be left floating.
Thermal Shutdown
When excessive power is dissipated in the
chip, the junction temperature rises. Once the
junction temperature exceeds the thermal
shutdown temperature the thermal shutdown
circuit turns off the converter output voltage
thus allowing the device to cool. When the
junction temperature decreases by 15C°, the
device will go through the normal startup
process.
Under Voltage Lockout
During initial power up an under voltage
lockout circuit will hold-off the switching
circuitry until the input voltage reaches a
sufficient level to insure proper operation. If
Application Information
or to a “high” logic voltage level. A logic “0”
indicates a connection to ground or to a “low”
logic voltage level. These pins can be either
hardwired to VIN or GND or alternatively can be
driven by standard logic levels. Logic low is
defined as VLOW ≤ 0.4V. Logic high is defined
as VHIGH ≥ 1.4V. Any level between these two
values is indeterminate. These pins must not
be left floating.
The External Voltage Divider pin, VFB, may be
left floating for all VID settings other than the
VS0=VS1=VS2= ”1”.
Output Voltage Select
To provide the highest degree of flexibility in
choosing output voltage, the EN5311QI uses a
3 pin VID, or Voltage ID, output voltage select
arrangement.
This allows the designer to
choose one of seven preset voltages, or to use
an external voltage divider.
Internally, the
output of the VID multiplexer sets the value for
the voltage reference DAC, which in turn is
connected to the non-inverting input of the
error amplifier. This allows the use of a single
feedback divider with constant loop gain and
optimum compensation, independent of the
output voltage selected.
Table 1 shows the various VS0-VS2 pin logic
states and the associated output voltage
levels. A logic “1” indicates a connection to VIN
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EN5311QI
VS1
0
0
1
1
0
0
1
1
VS0
0
1
0
1
0
1
0
1
VIN
4.7uF
VOUT
3.3V
2.5V
1.8V
1.5V
1.25V
1.2V
0.8V
User
Selectable
VS0
VS1
VS2
VS0
VS1
VS2
EN5311QI
4.7uF
VOUT
Ra
10µF
Input and Output Capacitors
VFB
The input capacitance requirement is 4.7uF.
Altera recommends that a low ESR MLCC
capacitor be used. The input capacitor must
use a X5R or X7R or equivalent dielectric
formulation.
Y5V or equivalent dielectric
formulations lose capacitance with frequency,
bias, and with temperature, and are not
suitable for switch-mode DC-DC converter
input and output filter applications.
Rb
GND
)
VOUT = 0.603V (1 + Ra
Rb
Ra must be chosen as 200KΩ to maintain loop
gain. Then Rb is given as:
The output capacitance requirement is a
minimum of 10uF.
The control loop is
designed to be stable with up to 60uF of total
output capacitance next to the output pins of
the device without requiring modification to the
compensation network. VOUT has to be sensed
at the last output filter capacitor next to the
device. Capacitance above the 10uF minimum
1.2 x10 5
Ω
VOUT − 0.603
VOUT can be programmed over the range of
0.6V to VIN – 0.6V (0.6 is the nominal full load
dropout voltage including margin).
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Rb
GND
Vout
The output voltage is selected by the following
formula:
=
b
VFB
Dynamic transitioning between internal VID
settings and the external divider is not allowed.
Figure 4. External Divider (VIN ≤ 5.5V).
R
10µF
The EN5311QI is designed to allow for
dynamic switching between the predefined VID
voltage levels. The inter-voltage slew rate is
optimized to prevent excess undershoot or
overshoot as the output voltage levels
transition. The slew rate is identical to the softstart slew rate of 1.65V/mS.
Figure 5 indicates the required connections for
VIN > 5.5V.
Vin
Ra 27pF
Dynamically Adjustable Output
For applications with VIN ≤ 5.5V, VSENSE must
be connected to VOUT as indicated in Figure 4.
VIN
Ca
For applications where VIN > 5.5V, the VSENSE
connection is not necessary, but the addition of
CA = 27pF is required.
As described above, the external voltage
divider option is chosen by connecting the
VS0, VS1, and VS2 pins to VIN or logic “high”.
The EN5311QI uses a separate feedback pin,
VFB, when using the external divider.
VSense
VOUT
Vout
Figure 5. External Divider (VIN > 5.5V).
External Voltage Divider
ENABLE
Vin
EN5311QI
VS2
0
0
0
0
1
1
1
1
VSense
ENABLE
Table 1. VID voltage select settings.
October 11, 2013
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Rev E
EN5311QI
Soft-Start for the maximum total capacitance
on the output.
should be added if the transient performance is
not sufficient using the 10uF.
Altera
recommends a low ESR MLCC type capacitor
be used.
The output capacitor must use a X5R or X7R
or equivalent dielectric formulation. Y5V or
equivalent
dielectric
formulations
lose
capacitance with frequency, bias, and
temperature and are not suitable for switchmode DC-DC converter input and output filter
applications.
Additional bulk capacitance for decoupling and
bypass can be placed at the load as long as
there is sufficient separation between the VOUT
Sense point and the bulk capacitance. The
separation provides an inductance that isolates
the control loop from the bulk capacitance.
Power-Up Sequencing
Excess total capacitance on the output (Output
Filter + Bulk) can cause an over-current
condition at startup. Refer to the section on
Cin
Manufacturer
Murata
Part #
Value
WVDC
Case Size
GRM219R61A475KE19D
GRM319R61A475KA01D
GRM219R60J475KE01D
GRM31MR60J475KA01L
4.7uF
4.7uF
4.7uF
4.7uF
10V
10V
10V
10V
0805
1206
0805
1206
ECJ-2FB1A475K
ECJ-3YB1A475K
ECJ-2FB0J475K
ECJ-3YB0J475K
4.7uF
4.7uF
4.7uF
4.7uF
10V
10V 1
6.3V 1
6.3V
0805
1206
0805
1206
LMK212BJ475KG-T
LMK316BJ475KD-T
JMK212BJ475KD-T
4.7uF
4.7uF
4.7uF
10V
10V 1
6.3V
0805
1206
0805
Panasonic
Taiyo Yuden
During power-up, ENABLE should not be
asserted before VIN. Tying these pins together
meets these requirements.
Cout
Manufacturer
Part #
Value
WVDC
Case Size
Murata
GRM219R60J106KE19D
GRM319R60J106KE01D
10uF
10uF
6.3V
6.3V
0805
1206
Panasonic
ECJ-2FB0J106K
ECJ-3YB0J106K
10uF
10uF
6.3V
6.3V
0805
1206
Taiyo Yuden
JMK212BJ106KD-T
JMK316BJ106KF-T
10uF
10uF
6.3V
6.3V
0805
1206
1. For V IN ≤ 5.5V
LAYOUT CONSIDERATIONS*
*Optimized PCB Layout file downloadable from the Altera Enpirion Website to assure first pass design success.
Recommendation 1: Input and output filter capacitors should be placed on the same side of the
PCB, and as close to the EN5311QI package as possible. They should be connected to the device
with very short and wide traces. Do not use thermal reliefs or spokes when connecting the capacitor
pads to the respective nodes. The +V and GND traces between the capacitors and the EN5311QI
should be as close to each other as possible so that the gap between the two nodes is minimized,
even under the capacitors.
Recommendation 2: DO NOT connect GND pins 3 and 4 together. Pin 3 should be used for the
Input capacitor local ground and pin 4 should be used for the output capacitor ground. The ground
pad for the input and output filter capacitors should be isolated ground islands and should be
connected to system ground as indicated in recommendation 3 and recommendation 5.
Recommendation 3: Multiple small vias (0.25mm after copper plating) should be used to connect
ground terminals of the Input capacitor and the output capacitor to the system ground plane. This
provides a low inductance path for the high-frequency AC currents; thereby reducing ripple and
suppressing EMI (see Fig. 6, Fig. 7, and Fig. 8).
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Recommendation 4: The large thermal pad underneath the component must be connected to the
system ground plane through as many thermal vias as possible. The vias should use 0.33mm drill
size with minimum one ounce copper plating (0.035mm plating thickness). This provides the path for
heat dissipation from the converter.
Recommendation 5: The system ground plane referred to in recommendations 3 and 4 should be
the first layer immediately below the surface layer (PCB layer 2). This ground plane should be
continuous and un-interrupted below the converter and the input and output capacitors that carry
large AC currents. If it is not possible to make PCB layer 2 a continuous ground plane, an
uninterrupted ground “island” should be created on PCB layer 2 immediately underneath the
EN5311QI and its input and output capacitors. The vias that connect the input and output capacitor
grounds, and the thermal pad to the ground island, should continue through to the PCB GND layer as
well.
Recommendation 6: As with any switch-mode DC/DC converter, do not run sensitive signal or
control lines underneath the converter package.
Recommendation 7: The VOUT sense point should be just after the last output filter capacitor next
to the device. Keep the sense trace short in order to avoid noise coupling into the node.
Recommendation 8: Keep Ra, Ca, and Rb close to the VFB pin (see Figures 4 and 5). The VFB pin is
a high-impedance, sensitive node. Keep the trace to this pin as short as possible. Whenever possible,
connect Rb directly to the GND pin instead of going through the GND plane.
Figure 6 shows an example schematic for the EN5311QI using the internal voltage select. In this
example, the device is set to a VOUT of 1.5V (VS2=0, VS1=1, VS0=1).
VFB
VSENSE
NC
NC
NC
NC
15
14
13
12
11
NC
7
VOUT
Rb=60K
Ra=200K
6
VOUT
VOUT
VOUT
VOUT
5
8
20
4
19
3
VS0
ENABLE
GND
NC
6
NC
9
GND
NC
11
16
NC
12
5
VOUT
VOUT
10
18
2
NC
13
4
NC
17
VS1
1
NC
14
3
7
GND
8
20
GND
19
VS2
VIN
VFB
VSENSE
15
VS0
ENABLE
2
NC
1
NC
9
VIN
10
18
VIN
17
VS1
VIN
VS2
16
Figure 7 shows an example schematic using an external voltage divider. VS0=VS1=VS2= “1”. The
resistor values are chosen to give an output voltage of 2.6V.
VOUT
VIN
VIN
4.7uF
10µF
(see layout recommendation 3)
Figure 6. Example application, Vout=1.5V.
4.7uF
10µF
(see layout recommendation 3)
Figure 7. Example Application, external divider, Vout = 2.6V.
Figure 8 shows an example board layout. The left side of the figure demonstrates construction of the
PCB top layer. Note the placement of the vias from the input and output filter capacitor grounds, and
the thermal pad, to the PCB ground on layer 2 (1st layer below PCB surface). The right side of the
figure shows the layout with the components populated. Note the placement of the vias per
recommendation 3.
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Figure 8. Example layout showing PCB top layer, as well as demonstrating use of vias from input, output filter
capacitor local grounds, and thermal pad, to PCB system ground.
Design Considerations for Lead-Frame Based Modules
Exposed Metal on Bottom of Package
Altera has developed a break-through in package technology that utilizes the lead frame as part of
the electrical circuit. The lead frame offers many advantages in thermal performance, in reduced
electrical lead resistance, and in overall foot print. However, it does require some special
considerations.
As part of the package assembly process, lead frame construction requires that for mechanical
support, some of the lead-frame cantilevers be exposed at the point where wire-bond or internal
passives are attached. This results in several small pads being exposed on the bottom of the
package.
Only the large thermal pad and the perimeter pin pads are to be mechanically or electrically
connected to the PC board. The PCB top layer under the EN5311QI should be clear of any metal
except for the large thermal pad. The “grayed-out” area in Figure 9 represents the area that should
be clear of any metal (traces, vias, or planes), on the top layer of the PCB.
NOTE: Clearance between the various exposed metal pads, the thermal ground pad, and the
perimeter pins, meets or exceeds JEDEC requirements for lead frame package construction (JEDEC
MO-220, Issue J, Date May 2005). The separation between the large thermal pad and the nearest
adjacent metal pad or pin is a minimum of 0.20mm, including tolerances. This is shown in Figure 10.
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Thermal Pad.
Connect to
Ground plane
Figure 9. Exposed metal and mechanical dimensions of the package. Gray area represents bottom metal noconnect and area that should be clear of any traces, planes, or vias, on the top layer of the PCB.
Figure 10. Exposed pad clearances; the Altera Enpirion lead frame package complies with JEDEC requirements.
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Figure 11. Recommended solder mask opening.
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Figure 12. Package mechanical dimensions.
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Ordering Information
Part Number
Temp Range
EN5311QI
EVB-EN5311QI
-40°C to +85°C
Package
QFN20
Evaluation Board
Tape & Reel
Contact Information
Altera Corporation
101 Innovation Drive
San Jose, CA 95134
Phone : 408-544-7000
www.altera.com
© 2013 Altera Corporation—Confidential. All rights reserved. ALTERA, ARRIA, CYCLONE, ENPIRION, HARDCOPY, MAX, MEGACORE, NIOS,
QUARTUS and STRATIX words and logos are trademarks of Altera Corporation and registered in the U.S. Patent and Trademark Office and in other
countries. All other words and logos identified as trademarks or service marks are the property of their respective holders as described at
www.altera.com/common/legal.html. Altera warrants performance of its semiconductor products to current specifications in accordance with Altera's
standard warranty, but reserves the right to make changes to any products and services at any time without notice. Altera assumes no responsibility or
liability arising out of the application or use of any information, product, or service described herein except as expressly agreed to in writing by Altera.
Altera customers are advised to obtain the latest version of device specifications before relying on any published information and before placing orders
for products or services.
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