Application Notes

AN10911
SD(HC)-memory card and MMC interface conditioning
Rev. 2 — 4 April 2013
Application note
Document information
Info
Content
Keywords
SD-memory card, Multi Media Card (MMC), ElectroStatic
Discharge (ESD) protection, ElectroMagnetic Interference (EMI) filtering
Abstract
This document gives an overview about different ESD protection and EMI
filter devices optimized for SD-memory card and MMC interfaces. These
devices cover the range from 1-bit to current standard 4-bit (SD-memory
card, SD 2.0) or 8-bit (MMC) high-speed memory card interfaces.
AN10911
NXP Semiconductors
SD(HC)-memory card and MMC interface conditioning
Revision history
Rev
Date
Description
2
20130404
Discontinued products removed
1
20100429
Initial version
Contact information
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: [email protected]
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SD(HC)-memory card and MMC interface conditioning
1. Introduction
The SD-memory card and MMC are the most popular memory cards in modern
communication, computer and consumer appliances. They support state-of-the-art
security and capacity requirements of modern audio and video applications in consumer
and communication products.
SD-memory cards support content protection, prevention of illegal use of content and
security systems based on, for example ISO-7816. An embedded version of MMC is
eMMC, according to the JESD84-A43. It offers up to 8-bit wide interface and can be
applied in SD-memory card compatible hardware interfaces.
While the SD-memory card adds an advanced data storage function to an application,
there is a more general Secure Digital Input Output (SDIO) card.
The SDIO card specification provides separately a specified interface to different I/O units.
It provides various functions to an SD host, including memory storage that is compatible
with the SD-memory card specification. Even if an SD host is not SDIO compatible (just
supporting SD-memory cards), no physical damage or disruption of operation will occur.
An SD-memory card communication is based on an advanced 8/9-pin interface (clock,
command, 1- or 4-bit data and 2/3  power/GND) designed to operate at a maximum
operating frequency of 50 MHz according to SD 2.0 specification.
The MMC works with an up to 52 MHz clock but supports in its latest versions up to 8 data
bits in a 13-pin interface (clock, command, 1-, 4- or 8-bit data, 3  power/GND).
While the SD-memory card can contain some ESD protection (see chapter 8.1.3. of Ref. 1
“SD specifications, part 1, Physical Layer Specification version 2.00, May 9, 2006”), SD
host interfaces require an additional high-level ESD protection according to the
IEC61000-4-2 standard in addition to the host-interface integrated ESD protection which
is typically very weak.
Strict EMI regulations and system requirements, as specified in GSM mobile phones,
request filters that reduce the radiated and/or conducted EMI but still comply with the
electrical requirements of the interface specification.
The continuing trend in miniaturization of portable appliances implies that interface
devices offering ESD protection and EMI filtering should also, where possible, integrate
biasing circuits or resistors into a single small-sized package.
NXP Semiconductors SD-memory card interface conditioning devices explained in this
document fully support this continuing trend and offer interface conditioning functions
such as:
• High-level ESD protection according the IEC61000-4-2 standard, often exceeding the
highest specified level 4
• EMI filtering, suppressing unwanted Radio Frequencies (RF), in combination with
SD interface compliant physical signaling
• Integrated biasing resistor networks to reduce the component count and to free up
additional space on the Printed-Circuit Board (PCB) surface
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SD(HC)-memory card and MMC interface conditioning
2. SD-memory card electrical interface
Today many appliances use 2.7 V to 3.6 V operating mode. It enables the use of a fixed
voltage interface and power supply to reduce cost and complexity of the control circuitry.
All further descriptions are related to this high-voltage range: 2.7 V to 3.6 V supply voltage
operated interfaces.
A list of SD-memory card threshold levels for this range is listed in Table 2.
2.1 SD-memory card and microSD card interfaces
The SD-memory card exhibits nine pins (eight pins in case of microSD card) that are used
to support electrical communication in two alternative communication protocols: SD and
SPI (Serial Peripheral Interface). The host system can choose either one of these modes.
The card detects which mode is requested by the host when the reset command is
received and expects all further communication to be in the same communication mode
(see Ref. 1).
Figure 1 shows an SD-memory card and microSD card with the interface pins.
9
1 2 3 4 5 6 7 8
WP
SD-memory
card
9 1 2 456 78
microSD
card
microSD card pin numbering complies with Table 1
Fig 1.
Shapes and interfaces of SD-memory card and microSD card (bottom view)
The SD bus includes the following signals:
•
•
•
•
AN10911
Application note
CLK: host to card clock signal
CMD: bidirectional command/response signal
DAT0 - DAT3: four bidirectional data signals
VDD, VSS1, VSS2: power and ground signals
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SD(HC)-memory card and MMC interface conditioning
The SPI bus includes the following signals:
•
•
•
•
CS: host to card chip select signal
CLK: host to card clock signal
DataIn: host to card data signal
DataOut: card to host data signal
The SPI interface uses 7 out of the SD 9 signals (DAT1 and DAT 2 are not used, DAT3 is
the CS signal) of the SD bus.
Table 1 summarizes the pins of the SD card interface as used in SD and SPI modes:
Table 1.
Interface pins of an SD-memory card and microSD card
Pin
SD mode
number Name
Type
Description
SPI mode
Name
Type
Description
1
CD/DAT3
I/O/PP
card-detect / data line (bit3)
CS
I
chip select (active low)
2
CMD
PP
command/response
DI
I
data in
3
GND1/VSS1
S
supply voltage ground
VSS
S
supply voltage ground
4
VDD
S
supply voltage
S
supply voltage
5
CLK
I
clock
I
clock
6
GND2/VSS2
S
supply voltage ground
S
supply voltage ground
7
DAT0
I/O/PP
data line (bit 0)
DO
O/PP
data out
8
DAT1
I/O/PP
data line (bit 1)
RSV
-
reserved
9
DAT2
I/O/PP
data line (bit 2)
RSV
-
reserved
[1]
SCLK
I: input, O: output, PP: input / output using push-pull drivers, S: power supply.
The signals listed in Table 1 are directly provided from the SD-memory card itself.
Additionally card holder can provide mechanical switches for card detection (CD) and
write protection (WP) mechanisms.
2.2 Bus operation conditions
The minimum output level of the driving device and the input level of the receiving device
are specified in Table 2 (see Ref. 1).
To decouple the SD-memory card interface specification from the signal-conditioning
device (EMI filter, ESD protection, etc.), an intermediate signal threshold is specified in
Table 3. This “EMI filter, card interface side” leveling is taken as a minimum requirement
for an SD-memory card compliant interface conditioning device.
As ESD protection and EMI filter devices should be placed as close as possible to the
contacts of the protected interface and integrate a major portion of the total bus
capacitance CBUS, they are responsible, as any other filter device, for most of the voltage
drop.
Then the high-level and the low-level output voltages of the filter or conditioning device
can be reduced (refer to VOH and VOL in Table 3) comparing to the output threshold levels
(see Table 2) and still exceed the input voltage level requirements.
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A detailed graphical overview of the different threshold levels at different positions of the
signal path is depicted in Figure 2, starting with the driver output on the left side and
ending with the receiving side on the right side of the drawing.
Three different threshold levels are shown in relation to each other in Figure 3, comparing
the SD-memory card output, the NXP Semiconductors signal-conditioning device output
and the SD-memory card input threshold levels.
Table 2.
SD-memory card threshold levels for high-voltage range
Values taken from Ref. 1
Symbol
Parameter
Min
Max
Unit
VSD
SD-memory card supply
voltage
2.7
3.6
V
VOH
high-level output voltage IOH = 100 A;
VSD = 2.7 V
0.75  VSD
-
V
VOL
low-level output voltage
-
0.125  VSD V
VIH
high-level input voltage
0.625  VSD
-
V
VIL
low-level input voltage
-
0.25  VSD
V
tPup
power up time
-
250
ms
Table 3.
Condition
IOL = 100 A;
VSD = 2.7 V
0 V  VSD  2.7 V
SD-memory card operating conditions
Symbol
Parameter
Min
Max
Unit
VSD
SD-memory card supply voltage
2.7
3.6
V
IDD
supply current in high-speed mode
-
200
mA
high-level output voltage
[1][3]
0.7  VSD -
VOL
low-level output voltage
[2][3]
-
CL
load capacitance
-
40
pF
CCARD
SD-memory card signal line capacitance
-
10
pF
-
30
pF
VOH
CHOST + BUS capacitance of host interface and signal bus
AN10911
Application note
V
0.2  VSD V
RCMD
external pull-up resistor value to prevent bus
floating
10
100
k
RDAT
external pull-up resistor value to prevent bus
floating; DAT0, DAT1 and DAT2
10
100
k
RDAT3
SD-memory card internal pull-up resistor value
DAT3/CD pin only
10
90
k
Lch
single line inductance
-
16
nH
[1]
SD-memory card specification is: VOH minimum is 0.75  VSD and VIH minimum is 0.625  VSD in Ref. 1;
NXP Semiconductors VOH minimum is 0.7  VSD.
[2]
SD-memory card specification is: VOL maximum is 0.125  VSD and VIL maximum is 0.25  VSD in Ref. 1;
NXP Semiconductors VOL minimum is 0.2  VSD.
[3]
20 % to 70 % limits are chosen also to cover MMC specification.
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SD(HC)-memory card and MMC interface conditioning
Host Output
Voltage Thresholds
NXP Interface Conditioning
Output Requirement
VSD
VOH = 0.75 * VSD
VOH = 0.7 * VSD
VOH = 0.7 * VSD
VIH = 0.625 * VSD
VIL = 0.25 * VSD
VOL = 0.2 * VSD
VOL = 0.2 * VSD
VOL = 0.125 * VSD
GND
VOL = 0.125 * VSD
GND
Host Output, driving
Fig 2.
VSD
VSD
VOH = 0.75 * VSD
SD Memory Card Input
Voltage Thresholds
GND
EMI-Filter
SD Memory Card
interface, receiving
Threshold voltage levels along the signal path
Driver side
minimum
requirement
Receiver side
minimum
requirement
Receiver side
minimum
requirement
VSD
VOH = 0.75 * VSD
VOH = 0.7 * VSD
VIH = 0.625 * VSD
Host output
threshold level
NXP filter output
threshold level
SD-memory card
input threshold level
VIL = 0.25 * VSD
VOL = 0.2 * VSD
VOL = 0.125 * VSD
GND
Fig 3.
Threshold voltage levels, output levels versus input levels
All further considerations are based on a chosen 20 % and 70 % threshold respectively,
related to the SD-memory card supply voltage VSD, as specified in Table 3, unless
otherwise indicated. These relative voltage levels also simplify an alignment with the MMC
specification.
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2.3 SD-memory card bus timing conditions
The SD-memory card interface has different timing requirements for the default mode and
for the high-speed mode up to 50 MHz clock frequency.
Special attention should be paid to the clock signal rise time and fall time requirements
(3 ns maximum).
All NXP Semiconductors devices support both the high-speed mode and the default mode
requirements. Since high-speed mode requirements contain default mode requirements,
only the former considered in this document.
Table 4.
SD-memory card timing conditions (high-speed mode)[1]
Symbol
Parameter
Condition
fPP
operating clock
frequency
tr
rise time
fall time
tf
Min
Max
Unit
0
50
MHz
20 % to 70 % of VDD
[2]
-
3
ns
70 % to 20 % of VDD
[2]
-
3
ns
[1]
Other timing parameters such as hold time, set-up time, high-level and low-level are dependent on the host
and SD-memory card interface and not significantly influenced by the NXP Semiconductors interface
conditioning devices.
[2]
Values refer to VOH and VOL specified for the EMI filter output.
2.4 Capacitive load at the interface conditioning device output
NXP Semiconductors devices, such as IP4352CX24, have rise time and fall time
requirements specified similarly to the data shown in Table 5.
Table 5.
Time domain response
Tamb = 25 C, VCC = 1.8 V, VBAT = 3.5 V, VSD = 2.9 V; 20 % to 70 % LOW-to-HIGH limits.
Symbol
Parameter
Test conditions
Min
Typ
Max
Unit
tr, tf
rise time, fall time
Zload = 20 pF || 100 k
-
1.5
2.5
ns
tr, tf
rise time, fall time
Zload = 40 pF || 100 k
-
2.7
3.6
ns
The following abbreviations are used:
• Zload: capacitive load representing CPCB2 + CHOLD + CCARD in NXP Semiconductors
data sheets
•
•
•
•
CPCBx: PCB trace capacitance
CHOLD: card holder capacitance
CBUS: total single bus channel capacitance excluding the SD-memory card
CL: total single bus channel capacitance including the SD-memory card
For further details refer to Figure 4.
In this specification, Zload represents CCARD and a part of CBUS.
Figure 4 depicts the various basic capacitances of the signal path summing up to:
C BUS = C PCB1 + C CH/2 + C CH/2 + C PCB2 + C HOLD  30 pF
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Note that a significant portion (NXP Semiconductors assumption 20 % to 30 %) of the
SD-memory cards available on the market today have a card capacitance (CCARD) of
more than 10 pF.
According to the SD-memory card specification (refer to chapter 6.5.5 of Ref. 1), the total
channel capacitance CL is defined as:
C L = C BUS + C CARD  40 pF
Assuming that state-of-the-art host interfaces show a capacitance of C HOST  4 pF and
the NXP Semiconductors interface-conditioning devices add a capacitance in the range of
C CH = 2  C CH/2  20 pF , a capacitance of C PCB1 + C PCB2 + C HOLD  6 pF is left for the
routing on the PCB and the card holder, which can already amount to 3 pF to 5 pF.
Due to Zload representing a lumped capacitance of 20 pF in addition to the filter channel
capacitance, it is obvious that the rise time and fall time requirement of 3 ns can be easily
fulfilled.
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SD(HC)-memory card and MMC interface conditioning
Host Interface
EMI-Filter
Memory Card Interface
A
B
CHOST
SD:
CCARD = 10 pF
MMC: CCARD 12 pF – 18 pF
CBUS
C
CPCB1
CHOLD
Cch/2
Cch/2
CPCB2
CHOST
SD:
CCARD = 10 pF
MMC: CCARD 12 pF – 18 pF
CFilter = 20 pF
SD:
MMC:
CHOST + CBUS = 30 pF
CHOST + CBUS = 18 pF
SD Memory Card:
Multi Media Card:
CL = 40 pF
CL = 30 pF
Note: CBUS is a lumped representative of the total channel capacitances of PCB, interface
conditioning and card holder.
A. Basic simplified memory card signal channel
B. More detailed level
C. Detailed memory card signal channel showing the relevant capacitive contributors
Fig 4.
AN10911
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Basic signal channel depicted in three different detail levels
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2.5 SD-memory card-detect mechanism
To detect an SD-memory card two different mechanisms can be used.
The conventional detection mechanism uses a mechanical switch in the card holder. The
other mechanism is based on the pull-up resistor integrated into the SD-memory card.
This resistor is connected to the DAT3/CD pin (where CD is card-detect). A detailed
schematic showing both detection mechanisms is depicted in Figure 6.
If MMC and SD-memory card are used in the same holder, only the mechanical
switch-based card detection can be used.
In contrast to the SD-memory card specification, the MMC specification does not specify
any internal pull-up resistors for an electrical card detection mechanism.
Additionally, the SD-memory card specification gives clear priority to the mechanical
switch detection method.
3. MMC electrical interface
Advanced appliances optimized for low-power consumption can operate MMCs at two
different supply voltages with small disadvantage of the increased control effort and a
selectable supply voltage. A number of MMC threshold levels for the high-voltage range
are listed in Table 6.
3.1 Bus operating conditions
The minimum output level of the driving device, together with the receiving device input
level is specified in Table 6 (see Ref. 2 “Multi Media Card System Specification version
4.3, JESD84-A43, November 2007”).
Similar considerations as shown in Section 2.3 “SD-memory card bus timing conditions”,
are also applicable to the MMC.
For high-voltage operation mode the threshold conditions are identical to the SD-memory
card conditions. Therefore both can be operated if connected to the same physical
interface as long as the electrical card detection mechanism is not used.
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Table 6.
MMC threshold levels
(values taken from Ref. 2)
Symbol
Parameter
Condition
VMMC
MMC supply voltage
high-voltage range
[1]
low-voltage range
Min
Max
Unit
2.7
3.6
V
1.7
1.95
V
0.75  VMMC
-
V
Push-pull mode bus signal level for high-voltage MMC
IOH = 100 A;
VMMCmin
VOH
high-level output
voltage
VOL
low-level output voltage IOL = 100 A;
VMMCmin
-
0.125*VMMC
V
VIH
high-level input voltage
0.625  VMMC
VMMC + 0.3
V
VIL
low-level input voltage
VSS  0.3
0.25  VMMC
V
Push-pull mode bus signal level for the dual voltage MMC in 1.70 V to 1.95 V mode for
high-voltage specified above for high-voltage MMC
VMMC  0.2
-
V
low-level output voltage IOL = 100 A;
VMMCmin
-
0.2
V
VIH
high-level input voltage
0.7  VMMC
VMMC + 0.3
V
VIL
low-level input voltage
VSS  0.3
0.3  VMMC
V
VOH
high-level output
voltage
VOL
[1]
IOH = 100 A;
VMMCmin
Low-voltage levels are part of the dual voltage range card specification including high-voltage range. The
voltage range from 1.95 V to 2.7 V is not specified.
Compared to the SD-memory card, the MMC bus is limited to a maximum of 30 pF
(SD-memory card is 40 pF maximum).
Two basic differences between MMC and SD-memory card are:
• minimum resistor value of RCMD which is less than a half of the specified minimum of
the SD-memory card specification
• DAT0 to DAT7 pull-up resistor values, starting at 50 k instead of 10 k in the
SD-memory card specification (see Table 3).
The Embedded Multi Media Card (eMMC) contains internal pull-up resistors at the pins
DAT1 to DAT7 to prevent floating of unconnected data lines (see Ref. 2). All other MMCs
do not contain any pull-up resistors to prevent bus floating.
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Table 7.
MMC operating conditions
Symbol
Parameter
Min
Max
Unit
CL
total bus capacitance for each signal line
-
30
pF
CCARD
single card signal line capacitance
CMICRO
-
12
pF
CMOBILE
-
18
pF
CBGA
-
12
pF
4.7
100
k
50
100
k
RCMD
CMD pull-up resistor value
RDAT7-DAT0 external DAT7 to DAT0 pull-up resistor value
[1]
RintDAT
eMMC internal DAT7 to DAT0 pull-up resistor value
50
150
k
Lch
maximum signal line capacitance
-
16
nH
[1]
except eMMC
3.2 Bus timing conditions
The MMC interface has different timing requirements for the default mode and for the
high-speed mode running up to 52 MHz. Special attention should be paid to the clock
signal rise and fall time requirement (3 ns maximum) which is similar to the high-voltage
range cards and the SD-memory card timing conditions (see Table 4).
Also, a reduced clock speed of up to 26 MHz can be used with these cards to save power
in appliances that do not require high data rates.
All NXP Semiconductors devices support both the high-speed mode and the default mode
requirements. Since high-speed mode requirements contain default mode requirements,
only the former considered in this document.
Table 8.
MMC timing conditions (high-speed mode)[1]
Symbol
Parameter
fPP
operating clock frequency
trise
high-speed mode clock rise time
tfall
high-speed mode clock fall time
[2]
Min
Max
Unit
0
52
MHz
-
3
ns
-
3
ns
[1]
Other timing parameters such as hold time, set-up time, high-time and low-time depend on the
host and MMC interface. They are not significantly influenced by NXP Semiconductors interface
conditioning devices.
[2]
Refer to Ref. 2, chapter 12.7.1 for further details.
3.3 Capacitive load at the interface conditioning device output
Refer to Section 2.4 for a detailed overview and calculation.
The drawing depicted in Figure 4 shows that it is difficult to build an MMC
specification-compliant bus system that includes high-level ESD protection and EMI
filtering. Nevertheless, most implementations used are related to the SD-memory card
application and use only slightly higher total channel capacitances, reaching the
SD specification for the value of CHOST + CBUS.
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4. SD-memory card and MMC interface comparison
A short summary of the main electrical interface parameters of the SD-memory card
versus the MMC are listed in the following table:
Table 9.
SD-memory card and MMC electrical parameters comparison
Symbol
Parameter
SD-memory
card
Vsd/MMC
memory card supply voltage
MMC
Unit
V
high-voltage range
2.7 - 3.6
2.7 - 3.6
low-voltage range
-
1.7 - 1.95 V
fPP
maximum operating clock frequency
50
52
MHz
trise
maximum high-speed mode clock rise time
3
3
ns
tfall
maximum high-speed mode clock fall time
3
3
ns
CL
maximum total bus capacitance for each
signal line
40
30
pF
CCARD
maximum capacitance single card signal line
10
-
pF
CMICRO
-
12
pF
CMOBILE
-
18
pF
CBGA
-
12
pF
10 - 100
4.7 - 100
k
10 - 100
50 - 100
k
-
50 - 150
k
RCMD
CMD pull-up resistor value
[1]
RDAT7(3)-0
external DAT7(3) - DAT0 pull-up resistor
value to prevent bus floating
RintDAT3
eMMC internal DAT7- DAT0 pull-up resistor
value
DAT3/CD (SD)
10 - 90
-
k
Lch
maximum signal line inductance
16
16
nH
[1]
except eMMC
5. Passive ESD protection and EMI filter devices
NXP Semiconductors offers a wide range of devices for the interface conditioning of the
SD-memory card and/or MMC interface. The product range covers EMI filters and ESD
protection devices, such as IP4252CZ12-6 or IP4252CZ16-8.
These devices can be also used for Serial Peripheral Interface (SPI)-based interface
operation modes. In this case 4-channel devices can be used although this is not the
preferred method of data exchange with SD-memory cards due to the lower speed and
single bit access.
An overview is given in Table 10 and a detailed description is given in the next chapters.
These filter devices are available in leadless plastic packages (DFN) and Wafer Level
Chip Size Packages (WLCSP).
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Even though the MMC and SD-memory card specifications state exact minimum and
maximum values for the various internal and external pull-up and pull-down resistors, a
majority of implemented interfaces in available appliances do not follow these
recommendations. This is especially true for the minimum CMD signal pull-up resistor
value, which is often undercut to guarantee a sufficiently short rise time in an open-drain
communication mode. The minimum values of the external pull-up resistor values of the
MMC specification are also sometimes replaced by values from the SD-memory card
specification range.
Therefore most NXP Semiconductors devices can be used in both interface applications,
MMCs and SD-memory cards, even though data sheets are referring to just one interface
type.
Modern memory cards typically support interfaces which are slightly out of the related
general interface specification.
Table 10.
SD-memory card and MMC interface devices overview
Product name
Device type
Additional
features
Number Package type and size
of filter
channels
Memory card interface ESD protection and EMI filter devices with integrated biasing (pull-up-/pull-down) resistors,
ESD protection level > 15 kV contact, far exceeding the IEC61000-4-2, level 4 (8 kV contact, 15 kV air)
IP4340CX15
ESD protection and EMI filter
IP4350CX24
ESD protection and EMI filter
IP4352CX24
ESD protection and EMI filter
IP4357CX17
ESD protection and EMI filter
6
CSP, 0.4 mm pitch
1.56  1.56  0.47 mm3
including
WP and CD
6 (+5) [1]
CSP, 0.4 mm pitch
2.01  2.02  0.61 mm3
including
WP and CD
6 (+5) [1]
CSP, 0.4 mm pitch
2.01  2.02 mm2
CSP, 0.4 mm pitch (staggered)
1.1  2.4 mm2
Memory card interface ESD protection and EMI filter devices, ESD protection level according IEC61000-4-2, level 4
(8 kV contact, 15 kV air discharge)
IP4252CZ8-4
ESD protection and EMI filter
4
DFN, 0.4 mm pitch
1.35  1.7  0.5 mm3
IP4252CZ12-6
ESD protection and EMI filter
6
DFN, 0.4 mm pitch
1.35  2.5  0.5 mm3
IP4252CZ16-8
ESD protection and EMI filter
8
DFN, 0.4 mm pitch
1.35  3.3  0.5 mm3
[1]
Numbers in brackets represent additional channels such as pull-up and pull-down channels, WP and CD that are not required for the
basic data communication.
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5.1 ESD protection EMI filter devices in plastic package IP4252CZ8-4,
IP4252CZ12-6, IP4252CZ16-8
If pull-up resistors are integrated in the host interface, then ESD protection and EMI
filtering devices such as IP4252 family are recommended. These devices are available
in 4-, 6- and 8-channel versions: IP4252CZ8-4, IP4252CZ12-6 andIP4252CZ16-8.
They all contain an RC-based pi-filter (also called Capacitor-Resistor-Capacitor (CRC)
filter) consisting of two ESD protection diodes, acting as filter capacitors, and a serial
channel resistor connected between the cathodes of these diodes.
Single filter channel schematic is shown in Figure 5 (left side) together with DFN plastic
packages (right side). These packages have 0.4 mm contact pitch and 0.5 mm maximum
package height.
Rs(ch)
Cch
2
Cch
2
GND
a. Schematic view for a single channel
Fig 5.
b. IP4252CZ8-4, IP4252CZ12-6 and IP4252CZ16-8
package (top to bottom)
IP4252: schematic view and package photograph
Table 11.
IP4252 parameters
Symbol Parameter
Conditions
VCC
supply voltage
VESD
electrostatic
discharge voltage
Min
Typ
Max
Unit
0.5
-
+5.6
V
8
-
+8
kV
IEC 61000-4-2, level 4;
all pins to ground
contact discharge
15
-
+15
kV
Rs(ch)
channel series
resistance
32
40
48

Cch
channel capacitance Vbias(DC) = 0 V,
f = 100 kHz
C ch
= 2 --------Vbias(DC) = 2.5 V,
2
f = 100 kHz
-
18
-
pF
-
12
-
pF
air discharge
[1]
Total channel capacitance is distributed between both ports of the channels, see Figure 5.
Due to the integrated symmetrical pi-filter structure (often referred to as CRC structure) all
NXP Semiconductors IP4252 devices offer a direction-independent and symmetrical ESD
protection as well as a direction-independent and symmetrical EMI filter performance.
Integrated pi-filter structures provide very low ESD clamping voltage compared to single
diode ESD protection implementations and/or devices.
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5.1.1 Application details of IP4252CZ12-6 and IP4252CZ16-8
Figure 6 shows a typical application of IP4252CZ12-6 and/or IP4252CZ16-8 in an
SD-memory card interface including both options for card detection. The grey-colored
components are optional and depend on the exact details of the interface implementation.
Especially with respect to the card-detect mechanism, either using a mechanical switch in
the card holder (preferred, see Ref. 1) or using integrated pull-up resistor at pin DAT3/CD
in combination with selectable pull-down / pull-up resistors. The exact resistor values have
to be aligned with all details described in Ref. 1.
This schematic does not include details concerning card-supply and typical power-supply
decoupling capacitors.
For the basic SD-memory card operation an IP4252CZ12-6 and 4 pull-up resistors
(10 k to 100 k) are sufficient for the digital data transmission from and to the
SD-memory card. MMCs require higher pull-up resistor values starting at 50 k. The card
detection mechanism has to be implemented using a CD channel as shown in Figure 7,
based on a mechanical card detection switch, in case SD-memory card and MMC are
used with the same interface.
optional
electrical
Card Detect
VCC(VSD)
DAT3/CD-pull -up
10 kΩ - 100 kΩ
Pull-up resistors
10 kΩ – 100 kΩ
to host interface
IP4252 CZ12-6
(IP4252 CZ16-8)
DAT1
DAT1
DAT0
CLK
CMD
GND
DAT3/CD
DAT2
CLK
CD
WP
SET_CLR_CARD_DETECT
(ACMD42)
V CC(VSD )
CMD
DAT3/CD-pull -down
> 270kΩ
Exact value depends
on required logic levels
SD Memory Card
DAT0
Optional :
2-additional channels
of IP4252 CZ16-8
10 kΩ - 90 kΩ
DAT3/CD
DAT2
CD
WP
Optional :
Card Detect switch
Optional :
Write Protect switch
Fig 6.
Application diagram of IP4252CZ12-6 and IP4252CZ16-8 in a SD-memory card interface
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The implementation of write protection contact is only possible in applications supporting
standard-size SD-memory cards. Smaller form-factor versions such as miniSD or
microSD do not support this feature. In case the mechanical slider mechanism of the
standard-size SD-memory card is used, a pull-up resistor is connected to the host supply
and a mechanical contact to ground. This contact is open until a WP slider is closing it
(mechanical adaptors converting a micro or mini SD-memory card into a standard
SD-card size typically do not support this feature).
VCC(VSD)
Pull -up resistors
10 kΩ – 100 kΩ
to host interface
IP4252 CZ16-8
DAT1
DAT1
DAT0
CLK
CMD
DAT0
SD Memory Card
GND
DAT3/CD
DAT2
CD
CLK
VCC (V SD )
WP
CMD
DAT3/CD
DAT2
CD
WP
Fig 7.
Application diagram of IP4252CZ16-8 using a mechanical card-detect switch
In case a mechanical card detection switch is not possible to apply (for example, due to
size constraints for the card holder), an electrical card detection can be used but only for
an SD-memory card interface.
After power-up DAT3/CD is connected to a 50 k (nominal value, specified range is 10 k
to 90 k) pull-up resistor inside the card. In case DAT3/CD is connected to a high-ohmic
pull-down resistor, the connected host can detect a logic level change from low to high
level1. The card internal pull-up resistor should be disconnected during regular data
transmission with SET_CLR_CARD_DETECT (ACMD42) command.
1.
It is recommended that pull-down resistor is >270 k to fulfill the logic voltage level requirements. The exact value depends on the
logic level requirements.
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Figure 8 shows a diagram for this implementation.
VCC(VSD)
Optional electrical
Card Detect
Pull-up resistors
10 kΩ – 100 kΩ
host interface
IP4252CZ12-6
SD Memory Card
DAT1
DAT1
DAT0
CLK
CMD
DAT0
GND
DAT3/CD
DAT2
SET_CLR_CARD_DETECT
(ACMD42)
CLK
VCC(V SD )
50 kΩ
pull-up
CMD
DAT3/CD
DAT3/CD-pull-down
> 270 kΩ,
Exact value depends
on required logic levels
Fig 8.
DAT2
Application diagram of IP4252CZ12-6 using electrical card detection
For the latest 8-bit MMC interface, 10 channels have to be ESD-protected and
EMI-filtered. A combination of IP4252CZ8-4 (4-channel) and IP4252CZ12-6 (6-channel) is
best-matching filter combination to cover the full interface (see Figure 9).
V CC(VMMC)
CMD Pull-up
resistor see text
Pull-up resistors
50 kΩ – 100 kΩ
IP4252 CZ12-6
DAT1
DAT0
DAT7
DAT6
DAT1
host interface
CLK
C7
VSS2
C6
CLK
C5
V CC
(VMMC )
C4
VSS1
C3
CMD
C2
DAT3
C1
DAT5
CMD
DAT4
DAT3
DAT2
C8
DAT7
C13
DAT6
C12
DAT5
C11
DAT4
C10
C9
IP4252 CZ8-4
Fig 9.
DAT0
DAT2
Application schematic diagram of IP4252CZ12-6 and IP4252CZ8-4 in an 8-bit MMC interface
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5.2 MicroSD card ESD protection and EMI filter device IP4340CX15
The IP4340CX15 is a 6-channel microSD card ESD protection and EMI filter device with 5
additionally integrated pull-up resistors in a tiny 0.4 mm ball pitch CSP.
The only channel without a pull-up resistor is the clock channel (see Figure 10). Due to
the pull-up resistor implementation, the electrical card detection method cannot be used.
Detection using a mechanical switch is mandatory.
The maximum filter channel capacitance is 14 pF which makes the device suitable to work
in high clock speed applications, too.
Table 12.
IP4340CX15 electrical parameters
Symbol Parameter
Conditions
VI
input voltage
VESD
electrostatic discharge
voltage
Min
Typ
Max Unit
0.5 -
+5.0 V
15
+15
kV
IEC 61000-4-2, level 4, pins on
microSD card side
contact discharge
-
15
-
+15
kV
Rs(ch)
channel series resistance R1 to R6
36
40
44

Rpu
pull-up resistance
R9 to R12
40
50
60
k
R13
12
15
18
k
including diode capacitance;
VI = 0 V; f = 1 MHz;
VCC = GND
8
11
14
pF
air discharge
Cline
line capacitance
VCC
R13
R12
R11
R10
R9
R1
CLK
SDCLK
R2
CMD
SDCMD
R3
DATA0
SDDATA0
R4
DATA1
SDDATA1
R5
DATA2
SDDATA2
R6
DATA3
SDDATA3
GND
aaa-003575
Fig 10. Schematic view for IP4340CX15
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5.3 Very highly integrated memory card interface device IP4350CX24
The IP4350CX24 demonstrates the highest level of integration, consisting of ESD
protection, EMI filter and biasing resistors in a passive device. As the package is a 0.4 mm
pitch CSP type, the total device size is only 1.95  2.11 mm2.
This device fully supports high-speed memory card interfaces working with clock speed
up to 52 MHz.
A special diode structure using a rail-to-rail (also known as “crow-bar”) diode concept on
the high-level ESD protection side in combination with single diodes on the low-level ESD
protection side guarantee a balanced distribution of the channel capacitance. This leads
to symmetrical EMI filter performance which is independent from the read/write direction.
IP4350CX24 supports electrical card detection of an SD-memory card using the pins
DAT3_PD and R21 connected to GND. Figure 11 shows detailed schematic with the driver
and control circuitry required to use electrical card detection. Electrical card-detect is
available as long as the “control” inverter output is low and 'driver_pu' is 3-stated, so R21
is acting as a pull-down to GND.
If normal operation is needed, the “control” inverter drives a high signal to enable the
'driver _pu' buffer, drives a high signal at R11 and also drives R21 to a high level to avoid
any unnecessary quiescent current.
The maximum voltage at the pin to the host interface may exceed the host supply voltage
as it is derived from: V SD   R 11   R 11 + R DAT3  CD pu   . In this case a voltage tolerant
input has to be selected.
If electrical card detection is not required, DAT3_PU (R11) should be connected to VSD
instead.
Since the CMD line is connected to the pull-up resistor R15, which is typically 15 k,
IP4350CX24 can also be used in combination with an MMC. The MMC can be initialized
using a 400 kHz open-drain mode.
The channels for the mechanical WP, CD and the combined WP+CD require an additional
pull-up resistor which is not integrated. Often pull-up resistors integrated into the GPIOs of
the host processor are used for this purpose as they can be switched off after detection.
The lower CMD pull-up resistor value and lower total line capacitance value make the
IP4350CX24 an excellent match for MMC interfaces in case a compliance with the latest
standard specification is mandatory.
Three additional channels support any configuration of CD and WP switches for the
various memory card holders (see Figure 11).
The most important electrical parameters are listed in Table 13.
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Table 13.
IP4350CX24 electrical parameters
Symbol Parameter
VI
input voltage
VESD
electrostatic discharge
voltage
Rs(ch)
Cch
AN10911
Application note
Conditions
Typ
Max Unit
0.5 -
+5.0 V
contact discharge
8
-
+8
kV
air discharge
15
-
+15
kV
IEC 61000-4-2, level 4
SDxxx pins to GND
12
15
18

R11 to R14
35
50
65
k
R15
3.29 4.7
6.11 k
R21
329
470
611
k
each data channel from
SD card to I/O interface
-
8.8
-
pF
CLK channel
-
7.8
-
pF
channel series resistance R1 to R9
channel capacitance
Min
including diode capacitance;
VI = 0 V; f = 100 kHz
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NXP Semiconductors
AN10911
Application note
IP4352CX24
DAT3_PU driver:
tri-stated for card detection
HIGH level during operation
IP4350CX24
VCC(VSD)
SD Memory Card
DAT3_PU
DAT1
PU driver
Control
DAT3_PD:
LOW level for card detection
HIGH level during operation
R12
R13
R14
R15
R4
SDDATA1
DATA0
R3
SDDATA0
R1
SDCLK
CMD
R2
SDCMD
DATA3
R6
SDDATA3
DATA2
R5
SDDATA2
CD
R7
SDCD
WP
R8
SDWP
WP+CD
R9
SDWP+CD
DAT3_PD
GND
CLK
CLK
(microSD)
DAT0
VCC(VSD)
50 kOhm
pull-up
SET_CLR_CARD_DETECT
(command ACMD42)
CMD
DAT3/CD
DAT2
R21
WP
GND_H
host side
Fig 11. IP4350CX24 connected to an SD-memory card using electrical card-detect
GND_C
connector side
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Card detect signal
or
DATA3 during operation
R11
DATA1
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NXP Semiconductors
AN10911
Application note
IP4352CX24
optional
electrical
card detect
IP4350CX24
VCC(VSD)
DAT3_PU
DAT1
R11
R12
R13
R14
R4
DATA1
SDDATA1
DAT0
GND
R3
SDDATA0
CLK
R1
SDCLK
CMD
R2
SDCMD
DATA3
R6
SDDATA3
DATA2
R5
SDDATA2
CD
R7
SDCD
WP
R8
SDWP
WP+CD
R9
SDWP+CD
CLK
VCC(VSD)
CMD
DAT3/CD
DAT2
R21
CD
WP
GND_C
GND_H
host side
(microSD)
connector side
Fig 12. IP4350CX24 connected to an SD-memory card using mechanical card-detect
AN10911
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DATA0
DAT3_PD
SD Memory Card
R15
AN10911
NXP Semiconductors
SD(HC)-memory card and MMC interface conditioning
6. Conclusion
NXP Semiconductors offers a comprehensive portfolio of SD-memory card and MMC
compatible interface conditioning and protection devices.
These devices are optimized for compliance with their respective memory card interface
in terms of channel capacitance, serial resistance and biasing resistor values.
Passive devices explained in this document protect from destruction from system level
ESD and also prevent disturbance of, for example wireless interfaces, from the harmonics
of the digital memory interfaces. Integrated biasing resistors contribute to gain the
maximum space savings comparing to discrete solutions.
All devices presented support a simple PCB layout, reduce the risk of EMI due to complex
layout of scattered discrete components and allow to minimize compliance testing.
The high integration level and the final test of each device before shipment also improve
the overall quality. The integrated protection and filter components reduce the number of
individual components, solder joints and pick-and-place processes.
7. References
AN10911
Application note
[1]
SD specifications, part 1, Physical Layer Specification version 2.00, May 9, 2006
[2]
Multi Media Card System Specification version 4.3, JESD84-A43, November 2007
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8. Legal information
8.1
Definitions
Draft — The document is a draft version only. The content is still under
internal review and subject to formal approval, which may result in
modifications or additions. NXP Semiconductors does not give any
representations or warranties as to the accuracy or completeness of
information included herein and shall have no liability for the consequences of
use of such information.
8.2
Disclaimers
Limited warranty and liability — Information in this document is believed to
be accurate and reliable. However, NXP Semiconductors does not give any
representations or warranties, expressed or implied, as to the accuracy or
completeness of such information and shall have no liability for the
consequences of use of such information. NXP Semiconductors takes no
responsibility for the content in this document if provided by an information
source outside of NXP Semiconductors.
In no event shall NXP Semiconductors be liable for any indirect, incidental,
punitive, special or consequential damages (including - without limitation - lost
profits, lost savings, business interruption, costs related to the removal or
replacement of any products or rework charges) whether or not such
damages are based on tort (including negligence), warranty, breach of
contract or any other legal theory.
Notwithstanding any damages that customer might incur for any reason
whatsoever, NXP Semiconductors’ aggregate and cumulative liability towards
customer for the products described herein shall be limited in accordance
with the Terms and conditions of commercial sale of NXP Semiconductors.
Right to make changes — NXP Semiconductors reserves the right to make
changes to information published in this document, including without
limitation specifications and product descriptions, at any time and without
notice. This document supersedes and replaces all information supplied prior
to the publication hereof.
Suitability for use — NXP Semiconductors products are not designed,
authorized or warranted to be suitable for use in life support, life-critical or
safety-critical systems or equipment, nor in applications where failure or
malfunction of an NXP Semiconductors product can reasonably be expected
to result in personal injury, death or severe property or environmental
damage. NXP Semiconductors and its suppliers accept no liability for
inclusion and/or use of NXP Semiconductors products in such equipment or
applications and therefore such inclusion and/or use is at the customer’s own
risk.
Applications — Applications that are described herein for any of these
products are for illustrative purposes only. NXP Semiconductors makes no
representation or warranty that such applications will be suitable for the
specified use without further testing or modification.
AN10911
Application note
Customers are responsible for the design and operation of their applications
and products using NXP Semiconductors products, and NXP Semiconductors
accepts no liability for any assistance with applications or customer product
design. It is customer’s sole responsibility to determine whether the NXP
Semiconductors product is suitable and fit for the customer’s applications and
products planned, as well as for the planned application and use of
customer’s third party customer(s). Customers should provide appropriate
design and operating safeguards to minimize the risks associated with their
applications and products.
NXP Semiconductors does not accept any liability related to any default,
damage, costs or problem which is based on any weakness or default in the
customer’s applications or products, or the application or use by customer’s
third party customer(s). Customer is responsible for doing all necessary
testing for the customer’s applications and products using NXP
Semiconductors products in order to avoid a default of the applications and
the products or of the application or use by customer’s third party
customer(s). NXP does not accept any liability in this respect.
Export control — This document as well as the item(s) described herein
may be subject to export control regulations. Export might require a prior
authorization from competent authorities.
Evaluation products — This product is provided on an “as is” and “with all
faults” basis for evaluation purposes only. NXP Semiconductors, its affiliates
and their suppliers expressly disclaim all warranties, whether express, implied
or statutory, including but not limited to the implied warranties of
non-infringement, merchantability and fitness for a particular purpose. The
entire risk as to the quality, or arising out of the use or performance, of this
product remains with customer.
In no event shall NXP Semiconductors, its affiliates or their suppliers be liable
to customer for any special, indirect, consequential, punitive or incidental
damages (including without limitation damages for loss of business, business
interruption, loss of use, loss of data or information, and the like) arising out
the use of or inability to use the product, whether or not based on tort
(including negligence), strict liability, breach of contract, breach of warranty or
any other theory, even if advised of the possibility of such damages.
Notwithstanding any damages that customer might incur for any reason
whatsoever (including without limitation, all damages referenced above and
all direct or general damages), the entire liability of NXP Semiconductors, its
affiliates and their suppliers and customer’s exclusive remedy for all of the
foregoing shall be limited to actual damages incurred by customer based on
reasonable reliance up to the greater of the amount actually paid by customer
for the product or five dollars (US$5.00). The foregoing limitations, exclusions
and disclaimers shall apply to the maximum extent permitted by applicable
law, even if any remedy fails of its essential purpose.
8.3
Trademarks
Notice: All referenced brands, product names, service names and trademarks
are the property of their respective owners.
All information provided in this document is subject to legal disclaimers.
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9. Contents
1
2
2.1
2.2
2.3
2.4
2.5
3
3.1
3.2
3.3
4
5
5.1
5.1.1
5.2
5.3
6
7
8
8.1
8.2
8.3
9
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
SD-memory card electrical interface . . . . . . . . 4
SD-memory card and microSD card interfaces 4
Bus operation conditions . . . . . . . . . . . . . . . . . 5
SD-memory card bus timing conditions . . . . . . 8
Capacitive load at the interface conditioning
device output . . . . . . . . . . . . . . . . . . . . . . . . . . 8
SD-memory card-detect mechanism . . . . . . . 11
MMC electrical interface . . . . . . . . . . . . . . . . . 11
Bus operating conditions . . . . . . . . . . . . . . . . 11
Bus timing conditions . . . . . . . . . . . . . . . . . . . 13
Capacitive load at the interface conditioning
device output . . . . . . . . . . . . . . . . . . . . . . . . . 13
SD-memory card and MMC interface
comparison. . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Passive ESD protection and EMI filter
devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
ESD protection EMI filter devices in plastic
package IP4252CZ8-4, IP4252CZ12-6,
IP4252CZ16-8 . . . . . . . . . . . . . . . . . . . . . . . . 16
Application details of IP4252CZ12-6 and
IP4252CZ16-8 . . . . . . . . . . . . . . . . . . . . . . . . 17
MicroSD card ESD protection and EMI filter
device IP4340CX15 . . . . . . . . . . . . . . . . . . . . 20
Very highly integrated memory card interface
device IP4350CX24 . . . . . . . . . . . . . . . . . . . . 21
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Legal information. . . . . . . . . . . . . . . . . . . . . . . 26
Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Trademarks. . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Please be aware that important notices concerning this document and the product(s)
described herein, have been included in section ‘Legal information’.
© NXP B.V. 2013.
All rights reserved.
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: [email protected]
Date of release: 4 April 2013
Document identifier: AN10911
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