ENPIRION EN5396QI

EN5396QI
9A Synchronous Buck PWM DC-DC
Converter with Integrated Inductor
External Output Voltage Programming
RoHS Compliant
Description
Features
The EN5396QI is a Power Supply on a Chip
(PwrSoC) DC-DC converter. It is specifically
designed to meet the precise voltage and fast
transient requirements of present and future
high-performance, low-power processor, DSP,
FPGA, ASIC, memory boards, and system level
applications in a distributed power architecture.
Advanced circuit techniques, ultra high switching
frequency,
and
innovative,
high-density,
integrated circuit and proprietary inductor
technology deliver high-quality, ultra compact,
non-isolated DC-DC conversion. Operating this
converter requires as few as five external
components that include small value input and
output ceramic capacitors and a soft-start
capacitor.
10mm
12mm
•
•
•
•
•
•
•
•
•
•
•
•
•
The Enpirion solution significantly helps in
system design and productivity by offering greatly
simplified
board
design,
layout
and
manufacturing requirements. In addition, a
reduction in the number of vendors required for
the complete power solution helps to enable an
overall system cost savings.
Applications
•
•
•
•
•
•
•
Point of load regulation for low-power
processors, network processors, DSPs,
FPGAs, and ASICs
Notebook computers, servers, workstations
Broadband, networking, LAN/WAN, optical
Low voltage, distributed power architectures
with 2.5V, 3.3V or 5V rails
DSL, STB, DVR, DTV, Industrial PC
Noise sensitive applications
Integrated Inductor Technology: Integrated
Inductor, MOSFETS, Controller in a 10 x 12 x
1.85mm package
Low External Part Count.
Up to 30W continuous output power.
Low output impedance optimized for ≤ 90 nm
Master/slave configuration for paralleling.
5MHz operating frequency.
High efficiency, up to 93%.
Wide input voltage range of 2.375V to 5.5V.
External resistor divider output voltage select.
Output Enable pin and Power OK signal.
Programmable soft-start time.
Adjustable over-current protection.
Thermal shutdown, short circuit, over-voltage
and under-voltage protection.
RoHS compliant, MSL level 3, 260C reflow.
Typical Application Circuit
VIN
1Ω
PVIN
VOUT
VOUT
AVIN
2 x 47µF
ENABLE
PGND
2 x 47µF
XOV
XFB
SS
15nF
AGND
PGND
Ordering Information
Part Number
EN5396QI-T
EN5396QI-E
Temp Rating (°C)
Package
-40 to +85
58-pin QFN T&R
QFN Evaluation Board
©Enpirion 2009 all rights reserved, E&OE
02393
Figure 1. Simple Layout.
1
11/12/2009
www.enpirion.com
Rev:C
March 2009
EN5396QI
Pin Configuration
Below is a top view diagram of the EN5396Q package.
NOTE: NC pins are not to be electrically connected to each other or to any external signal, ground, or voltage.
However, they must be soldered to the PCB. Failure to follow this guideline may result in part malfunction or
damage.
Figure 2. Pin Diagram, top view.
©Enpirion 2009 all rights reserved, E&OE
02393
2
11/12/2009
www.enpirion.com
Rev:C
EN5396QI
Pin Descriptions
PIN
NAME
1-3
NC
4-5
NC(SW)
6-13
NC
14-20
VOUT
21-22
NC(SW)
23
NC
24-29
30-35
PGND
PVIN
36-37
NC
38
ROCP
39
40
AVIN
AGND
41-42
NC
43
44
XFB
XOV
45
NC
46
POK
47
NC
48
SS
49
50
EAIN
EAOUT
51
COMP
52
ENABLE
53
PWM
54
NC
55
M/S
56-58
NC
FUNCTION
NO CONNECT – This pin should not be electrically connected to any external signal, voltage,
or ground, but must be soldered to PCB. This pin may be connected internally.
NO CONNECT – These pins are internally connected to the common drain output of the
internal MOSFETs. NC(SW) pins are not to be electrically connected to any external signal,
ground, or voltage. However, they must be soldered to the PCB. Failure to follow this guideline
may result in part malfunction or damage.
NO CONNECT – This pin should not be electrically connected to any external signal, voltage,
or ground, but must be soldered to PCB. This pin may be connected internally.
Regulated converter output. Connect these pins to the load and place output capacitor from
these pins the PGND pins 24-26.
NO CONNECT – These pins are internally connected to the common drain output of the
internal MOSFETs. NC(SW) pins are not to be electrically connected to any external signal,
ground, or voltage. However, they must be soldered to the PCB. Failure to follow this guideline
may result in part malfunction or damage.
NO CONNECT – This pin should not be electrically connected to any external signal, voltage,
or ground, but must be soldered to PCB. This pin may be connected internally.
Output power ground. Refer to layout guideline section.
Input power supply. Connect to input power supply. Decouple with input capacitor to PGND.
NO CONNECT – This pin should not be electrically connected to any external signal, voltage,
or ground, but must be soldered to PCB. This pin may be connected internally.
Optional Over Current Protection adjust pin. Place ROCP resistor between this pin and AGND
(pin 40) to adjust the over current trip point.
Analog voltage input for the controller circuits. Connect this pin to the input power supply.
Analog ground for the controller circuits.
NO CONNECT – This pin should not be electrically connected to any external signal, voltage,
or ground, but must be soldered to PCB. This pin may be connected internally.
Feedback pin for external voltage divider network.
Over voltage programming feedback pin.
NO CONNECT – This pin should not be electrically connected to any external signal, voltage,
or ground, but must be soldered to PCB. This pin may be connected internally.
Power OK is an open drain transistor for power system state indication. POK is a logic high
when VOUT is with -10% to +20% of VOUT nominal.
NO CONNECT – This pin should not be electrically connected to any external signal, voltage,
or ground, but must be soldered to PCB. This pin may be connected internally.
Soft-Start node. The soft-start capacitor is connected between this pin and AGND. The value
of this capacitor determines the startup timing.
Optional Error Amplifier input. Allows for customization of the control loop.
Optional Error Amplifier output. Allows for customization of the control loop.
Output of the buffer leading to the error amplifier. Used for external modifications of the
compensation network.
Input Enable. Applying a logic high, enables the output and initiates a soft-start. Applying a
logic low disables the output.
PWM input/output. Used for optional master/slave configuration. When M/S pin is asserted
“low”, PWM will output the gate-drive PWM waveform. When the M/S pin is asserted “high”,
the PWM pin is configured as an input for PWM signal from the “master” device. PWM pin
can drive up to 3 slave devices.
NO CONNECT – This pin should not be electrically connected to any external signal, voltage,
or ground, but must be soldered to PCB. This pin may be connected internally.
Optional Master/Slave select pin. Asserting pin “low” places device in Master Mode for current
sharing. PWM pin (53) will output PWM drive signal. Asserting pin “high” will place the device
in Slave Mode. PWM pin (53) will be configured to input (receive) PWM drive signal from
“Master” device.
NO CONNECT – This pin should not be electrically connected to any external signal, voltage,
or ground, but must be soldered to PCB. This pin may be connected internally.
©Enpirion 2009 all rights reserved, E&OE
02393
3
11/12/2009
www.enpirion.com
Rev:C
EN5396QI
Block Diagram
POK
PVIN
UVLO
Power
Good
Logic
Thermal Limit
ROCP
Current Limit
Over
Voltage
XOV
VOUT
Over Voltage
NC(SW)
P-Drive
VOUT
(-)
(+
)
N-Drive
PWM
Comp
PGND
Compensation
Sawtooth
Generator
VSENSE
Voltage
Selector
(-)
Error
Amp
ENABLE
SS
XFB
(+
)
Reference
Voltage
selector
Soft Start
Bandgap
Reference
EAOUT
EAIN
COMP AVIN
AGND
Figure 3. System block diagram.
©Enpirion 2009 all rights reserved, E&OE
02393
4
11/12/2009
www.enpirion.com
Rev:C
EN5396QI
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
Input Supply Voltage
Voltages on: ENABLE, VSENSE, XFB, XOV, M/S
Voltages on: EAIN, EAOUT, COMP
Voltages on: SS, PWM
Voltages on: POK
Storage Temperature Range
Reflow Temp, 10 Sec, MSL3 JEDEC J-STD-020A
ESD Rating (based on Human Body Model)
SYMBOL
MIN
MAX
UNITS
VIN
-0.5
-0.5
-0.5
-0.5
-0.5
-65
7.0
VIN
2.5
3.0
VIN + 0.3
150
260
V
V
TSTG
°C
°C
V
2000
Recommended Operating Conditions
PARAMETER
SYMBOL
Input Voltage Range
VIN
Output Voltage Range (NOTE: 1)
VOUT
Output Current (NOTE 2)
IOUT
Operating Ambient Temperature
TA
Operating Junction Temperature
TJ
Note 1: VDROPOUT = ILOAD x Dropout Resistance
Note 2: Reference figures 5 and 6 for the Output Current Derating Curves.
MIN
MAX
UNITS
2.375
0.75
0
-40
-40
5.5
VIN - VDROPOUT
9
+85
+125
V
V
A
°C
°C
Thermal Characteristics
PARAMETER
SYMBOL
TYP
UNITS
Thermal Resistance: Junction to Ambient (0 LFM) (Note 3)
θJA
18
Thermal Resistance: Junction to Case (0 LFM)
θJC
1.5
Thermal Overload Trip Point
TJ-TP
+150
Thermal Overload Trip Point Hysteresis
20
Note 3: Based on four layer board and proper thermal design in line with JEDEC EIJ/JESD 51 standards
°C/W
°C/W
°C
°C
Electrical Characteristics
NOTE: VIN=5.5V over operating temperature range unless otherwise noted.
Typical values are at TA = 25°C.
PARAMETER
VOUT Initial Accuracy
Overall VOUT Accuracy
(Line, Load, and
Temperature combined)
Transient Response Peak
Deviation
Under Voltage Lock out
threshold
SYMBOL
∆VOUT_INIT
∆VOUT_ALL
∆VOUT
VUVLO
©Enpirion 2009 all rights reserved, E&OE
02393
TEST CONDITIONS
TA = 25C, 2.375V ≤ VIN ≤ 5.5V
ILOAD = 1A; TA = 25°C
2.4V ≤ VIN ≤ 5.5V
-40°C ≤ TA ≤ +85°C
0A ≤ ILOAD ≤ 9A
(IOUT = 0% to 100% or 100% to
0% or rated load)
VIN = 5V, 1.2V ≤ VOUT ≤ 3.3V
COUT = 2 x 47 µF
VIN Increasing
VIN Decreasing
5
11/12/2009
MIN
TYP
MAX
UNITS
-2
2
%
-3%
+3%
3
%
2.2
2.1
V
www.enpirion.com
Rev:C
PARAMETER
Switching Frequency
Continuous Output Current
SYMBOL
IOUT
Current Limit Threshold
Shut-Down Supply Current
IOCP_TH
IS
Disable Threshold
VDISABLE
Enable Threshold
VENABLE
Enable Pin Current
POK threshold High
POK threshold Low
POK Low Voltage
POK High Voltage
Dropout Resistance
Current Balance
IEN
∆IOUT
©Enpirion 2009 all rights reserved, E&OE
02393
TEST CONDITIONS
MIN
FSWITCH
TYP
EN5396QI
MAX UNITS
5
2.375V ≤ VIN ≤ 5.5V
0.603 <VOUT < VIN-0.5
TA = -40°C to +60°C
NOTE: reference figures 5 and 6
for the output current derating
curves
ENABLE=0V
Max voltage to ensure the
converter is disabled
2.375V ≤ VIN ≤ 5.5V
5.5V < VIN
VIN = 5.5V
Percentage of VOUT Nominal
Percentage of VOUT Nominal
IPOK = 4mA (Max Sink Current)
With 2 – 4 converters in parallel,
the difference between any 2
parts. ∆VIN < 50mV; RTRACE <
10mΩ.
6
11/12/2009
MHz
9
A
11
50
A
µA
0.8
1.8
2.0
V
V
50
µA
%
%
V
V
mΩ
+/-10
%
50
120
90
0.4
VIN
www.enpirion.com
Rev:C
EN5396QI
Typical Performance Characteristics
Circuit of Figure 1, VIN = 5 V, VOUT = 1.2 V and TA = 25°C, unless otherwise noted.
Efficiency (VIN =3.3V)
Efficiency (Vin = 5.0V)
95
85
Efficiency (%)
Efficiency (%)
90
80
75
70
65
60
0
2
4
6
8
95
90
85
80
75
70
65
60
55
50
0
10
2
4
6
8
10
Load (Amperes)
Load (Amperes)
Top to Bottom: VOUT = 2.5 V, 1.8 V, 1.5 V, 1.2 V, 0.8 V
Top to Bottom: VOUT = 3.3 V, 2.5 V, 1.8 V, 1.5 V, 1.2 V, 0.8 V
Ripple Voltage, 5.5VIN/1.2VOUT, IOUT=9A,
COUT = 5x22uF.
Ripple Voltage, 3.3VIN/1.2VOUT, IOUT=9A,
COUT = 5x22uF.
Transient Response: 5VIN/1.2VOUT, 0-9A, 7A/uS.
COUT = 5x22uF.
Transient Response: 5VIN/3.3VOUT, 0-9A, 7A/uS.
COUT = 5x22uF
©Enpirion 2009 all rights reserved, E&OE
7
02393
11/12/2009
www.enpirion.com
Rev:C
EN5396QI
Start up waveforms VIN=5.0V, VOUT=1.2V, CSS=15nF,
Ch 1 = VOUT, Ch 3 = ENABLE, Ch 4 = POK.
©Enpirion 2009 all rights reserved, E&OE
02393
Start up waveforms VIN=5.0V, VOUT=3.3V, CSS=15nF,
Ch 1 = VOUT, Ch 3 = ENABLE, Ch 4 = POK.
8
11/12/2009
www.enpirion.com
Rev:C
EN5396QI
Functional Description
The EN5396QI is a synchronous, pin
programmable power supply with integrated
power MOSFET switches and integrated
inductor. The nominal input voltage range is
2.375-5.5V. The output voltage is programmed
using an external resistor divider network. The
feedback control loop is a type III voltage-mode
and the part uses a low-noise PWM topology.
Up to 9A of output current can be drawn from this
converter. The 5MHz operating frequency
enables the use of small-size output capacitors.
Ra1 =
(Vout − 0.75V ) * Rb1
0.75V
If over-voltage protection is desired, use the
following equation to set the resistor Ra2 for the
desired OVP trip-point:
Ra 2 =
(OVPtrip − 0.90V ) * Rb 2
0.90V
By design, if both resistor dividers are the same,
the OV trip-point will be 20% above the nominal
output voltage.
The power supply has the following protection
features:
• Programmable over-current protection (to
protect the IC from excessive load current)
• Thermal shutdown with hysteresis.
• Over-voltage protection
• Under-voltage lockout circuit to disable the
converter output when the input voltage is
less than approximately 2.2V
VIN
PVIN
2x
47µF
POK
VOUT
VOUT
Ra2
XOV
AVIN
2 x 47µF
XFB
SS
Rb2
CSS
AGND
Additional features include:
• Soft-start circuit, limiting the in-rush
current when the converter is powered up.
• Power good circuit indicating whether the
output voltage is within 90%-120% of the
programmed voltage.
Ra1
Rb1
PGND
Figure 4. VOUT and OVP resistor divider networks.
NOTE: if no OVP divider is present, there will be no overvoltage protection and POK will remain “high” as long as
VOUT remains above 90% of the nominal VOUT setting.
Programming Output Voltage and OVP
Input Capacitor Selection
The EN5396 output voltage is programmed using
a simple resistor divider network. Figure 4 shows
the resistor divider configuration.
The EN5396QI requires approximately 100uF of
input capacitance. Low ESR ceramic capacitors
are required with X5R or X7R rated dielectric
formulation.
Y5V or equivalent dielectric
formulations must not be used as these lose
capacitance with frequency, temperature and
bias voltage.
The EN5396 output voltage and over voltage
thresholds are determined by the voltages
presented at the XFB and XOV pins respectively.
These voltages are set by way of resistor dividers
between VOUT and AGND with the midpoint going
to XFB and XOV.
In some applications, lower value capacitors are
needed in parallel with the larger, capacitors in
order to provide high frequency decoupling.
It is recommended that Rb1 and Rb2 resistor
values be ~2kΩ. Use the following equation to
set the resistor Ra1 for the desired output
voltage:
©Enpirion 2009 all rights reserved, E&OE
02393
9
11/12/2009
www.enpirion.com
Rev:C
EN5396QI
Recommended input capacitors.
Description
47uF, 10V,
X5R, 1210
(2 capacitors needed)
MFG
Murata
Output Capacitor
Configuration
P/N
GRM32ER61A476KE20L
Taiyo Yuden
2 x 47uF
5 x 22 uF
LMK325BJ476MM-T
Enable Operation
Output Capacitor Selection
The EN5396QI has been optimized for use with
approximately 100µF of output capacitance. Low
ESR ceramic capacitors are required with X5R or
X7R rated dielectric formulation.
Y5V or
equivalent dielectric formulations must not be
used as these loose capacitance with frequency,
temperature and bias voltage.
MFG
Murata
P/N
GRM31CR60J226KE19L
Taiyo Yuden
JMK316BJ226KL-T
Murata
GRM32ER61A476KE20L
AVX
12106D476KAT2
Soft start is a method to reduce in-rush current
when the device is enabled. The output voltage
is ramped up slowly upon start-up. The output
rise time is controlled by choice of a soft-start
capacitor, which is placed between the SS pin
(pin 48) and the AGND pin (pin 40).
Output ripple voltage is determined by the
aggregate output capacitor impedance. Output
impedance, denoted as Z, is comprised of
effective series resistance, ESR, and effective
series inductance, ESL:
Z = ESR + ESL.
Placing output capacitors in parallel reduces the
impedance and will hence result in lower ripple
voltage.
1
Z Total
=
The ENABLE pin provides a means to shut down
the device, 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. When the ENABLE pin is
asserted high, the device will undergo a normal
soft start.
Soft-Start Operation
Recommended output capacitors.
Description
22uF, 6.3V, 10%
X5R, 1206
(5 capacitors needed)
47uF, 10V, 10%
X5R, 1210
47uF, 6.3V, 10%
X5R, 1210
(2 capacitors needed)
Typical Output Ripple (mVp-p)
(as measured on EN5396QI
Evaluation Board)
20
12
1
1
1
+
+ ... +
Z1 Z 2
Zn
Typical ripple versus capacitor arrangement is
given below (5.5VIN/1.2VOUT):
Rise Time: TR = Css* 80KΩ
During start-up of the converter, the reference
voltage to the error amplifier is gradually
increased to its final level by an internal current
source of typically 10uA. Typical soft-start rise
time is 1mS to 3mS. Typical SS capacitor values
are in the range of 15nF to 30 nF.
POK Operation
The POK signal is an open drain signal from the
converter indicating the output voltage is within
the specified range. The POK signal will be a
logic high when the output voltage is within 90% 120% of the programmed output voltage. If the
output voltage goes outside of this range, the
POK signal will be a logic low until the output
voltage has returned to within this range. In the
event of an over-voltage condition the POK
signal will go low and will remain in this condition
until the output voltage has dropped to 95% of
the programmed output voltage before returning
to the high state.
The internal POK FET is designed to tolerate up
to 4mA. The pull-up resistor value should be
©Enpirion 2009 all rights reserved, E&OE
02393
10
11/12/2009
www.enpirion.com
Rev:C
chosen to limit the current from exceeding this
value when POK is logic low.
Over-Current Protection
When an over current condition occurs, VOUT is
pulled low. This condition is maintained for a
period of 1.2 ms and then a normal soft start
cycle is initiated. If the over current condition still
persists, this cycle will repeat.
The OCP trip point is nominally set to 150% of
maximum rated load. It is possible to increase
the OCP trip point to 200% of the maximum rated
load by connecting a 5kΩ resistor between the
ROCP pin (pin 38) and AGND (pin 39). This
option is intended for startup into capacitive
loads such as certain FPGAs and ASICs.
Over-Voltage Protection
When the output voltage exceeds 120% of the
programmed output voltage, the PWM operation
stops, the lower N-MOSFET is turned on and the
POK signal goes low. When the output voltage
drops below 95% of the programmed output
voltage, normal PWM operation resumes and
POK returns to its high state.
EN5396QI
types.) Voltage mode operation provides high
noise immunity at light load.
In some cases modifications to the compensation
may be required. The EN5396QI provides access
to the internal compensation network to allow for
customization. For more information, contact
Enpirion Applications Engineering support.
Parallel Device Operation
In order to power a load that is higher than the
rated 9A of the EN5396, from 2 to 4 devices can
be placed in parallel for providing a single load
with up to 24A of output current.
Paralleling more than 1 device is accomplished
by selecting a master device and tying that M/S
pin to AGND. All slave devices should have their
M/S pin tied to AVIN. The PWM pin from the
master device is connected to all slave device
PWM pins. The PWM signal is a 5 MHz drive
signal and must be routed appropriately. (See
Figure 4.)
1. All master and slave devices should have
identical placement and values of input,
output and soft-start capacitors.
2. All master and slave devices should have
their ENABLE pins tied together and
should be operated simultaneously with a
fast rising edge of 10 uSec or less, to
ensure that devices start up at the same
time. Startup imbalance could lead to
OCP condition on first device to startup.
3. The maximum board trace resistance
between any 2 devices VOUT pins should
be less than 10mΩ.
4. The maximum difference of PVIN between
any 2 devices should be less than 50mV.
Thermal Overload Protection
Thermal shutdown will disable operation once
the Junction temperature exceeds approximately
150ºC. Once the junction temperature drops by
approx 20ºC, the converter will re-start with a
normal soft-start.
Input Under-voltage Lock-out
Circuitry is provided to ensure that when the
input voltage is below the specified voltage
range, the converter will not start-up. Circuits for
hysteresis, input de-glitch and output leading
edge blanking are included to ensure high noise
immunity and prevent false tripping.
Compensation
The EN5396 is internally compensated through
the use of a type 3 compensation network and is
optimized for use with about 50µF of output
capacitance and will provide excellent loop
bandwidth and transient performance for most
applications. (See the section on Capacitor
Selection for details on recommended capacitor
©Enpirion 2009 all rights reserved, E&OE
02393
11
11/12/2009
www.enpirion.com
Rev:C
EN5396QI
Figure 4 . Paralleling of two devices.
Figure 5. Output Current Derating Curve, VIN = 5.0V
©Enpirion 2009 all rights reserved, E&OE
02393
12
11/12/2009
www.enpirion.com
Rev:C
EN5396QI
Figure 6 . Output Current Derating Curve, VIN = 3.3V
©Enpirion 2009 all rights reserved, E&OE
02393
13
11/12/2009
www.enpirion.com
Rev:C
EN5396QI
Layout Recommendations
Vias to System
Ground Plane
VIN(+)
Plane
VOUT(+)
Plane
Local
Ground
Plane
Package
Outline
Slit separating
input local ground
from output
local ground
Output Capacitor
Landing Pads
Figure 7. Layout of power and ground planes.
Output Local
Ground Plane
vias as possible. The diameter of the vias
should be less than 0.3mm. This provides the
quiet, or analog ground for the converter and
also provides the path for heat dissipation from
the converter. A later section of this note
makes a recommendation on the PCB
footprint.
Recommendation 2: Place a slit in the
input/output capacitor ground plane just
beyond the common connection point of the
GND pins of the device as shown in figure 7.
Recommendation 5: The system ground
plane referred to in recommendations 3 and 4
should be the first layer immediately below the
surface layer. This ground plane should be
continuous and un-interrupted below the
converter and the input and output capacitors
that carry large AC currents.
Recommendation 3: Multiple small (0.25mm)
vias should be used to connect ground terminal
of the Input capacitor and the output capacitor
to the system ground plane as shown in figure
8.
Recommendation 6: As with any switch-mode
DC/DC converter, do not run sensitive signal or
control lines underneath the converter
package.
Recommendation 4: The large thermal pad
underneath the component must be connected
to the system ground plane through as many
02393
Input Local
Ground Plane
Figure 8. Use of vias connecting local and system ground.
Recommendation 1: Input and output
capacitors should be placed as close to the
EN5396QI package as possible to reduce EMI
from input and output loop currents. This
reduces the physical area of the Input and
Output AC current loops.
©Enpirion 2009 all rights reserved, E&OE
Input Capacitor
Landing Pads
14
11/12/2009
www.enpirion.com
Rev:C
EN5396QI
Design Considerations for Lead-Frame Based Modules
Exposed Metal on Bottom of Package
Lead frame offers many advantages in thermal performance, in reduced electrical lead resistance, ,
and in overall foot print. However, they do require some special considerations.
In the 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 pads are to be mechanically or electrically connected to
the PC board. The PCB top layer under the EN5396QI 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.
Figure 10 demonstrates the recommended PCB footprint for the EN5396QI. Figure 11 shows the
shape and location of the exposed metal pads as well as the mechanical dimension of the large
thermal pad and the pins.
Figure 9. Lead-Frame exposed metal. Grey area highlights exposed metal that is not to be mechanically or
electrically connected to the PCB.
©Enpirion 2009 all rights reserved, E&OE
02393
15
11/12/2009
www.enpirion.com
Rev:C
EN5396QI
Figure 10. Recommended footprint for PCB.
©Enpirion 2009 all rights reserved, E&OE
02393
16
11/12/2009
www.enpirion.com
Rev:C
EN5396QI
Package Dimensions
Figure 11. Package dimensions.
©Enpirion 2009 all rights reserved, E&OE
02393
17
11/12/2009
www.enpirion.com
Rev:C
EN5396QI
TAPE AND REEL SPECIFICATION
©Enpirion 2009 all rights reserved, E&OE
02393
18
11/12/2009
www.enpirion.com
Rev:C
EN5396QI
Contact Information
Enpirion, Inc.
Perryville III
53 Frontage Road, Suite 210
Hampton, NJ 08827
Phone: 908-894-6000
Fax: 908-894-6090
Enpirion reserves the right to make changes in circuit design and/or specifications at any time without notice. Information furnished by Enpirion is
believed to be accurate and reliable. Enpirion assumes no responsibility for its use or for infringement of patents or other third party rights, which may
result from its use. Enpirion products are not authorized for use in nuclear control systems, as critical components in life support systems or equipment
used in hazardous environment without the express written authority from Enpirion.
©Enpirion 2009 all rights reserved, E&OE
02393
19
11/12/2009
www.enpirion.com
Rev:C