AN3809, Our Power Management ICs for High End Processors

Freescale Semiconductor
Application Note
AN3809
Rev. 1.0, 12/2008
Powering the i.MX27 with the 5 Channel
MC34704B IC
1
Overview
This document presents an analysis of the possibility to
use the 5 Channel MC34704B power management IC to
supply a system based on i.MX27. The focus was done
on i.MX27 itself, considering its needs in terms of
voltage, current and power up sequence. The needs to
supply the DDR and Flash memories were also taken
into account.
2
Scope
Contents
1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
3 i.MX27 Power Requirements . . . . . . . . . . . . . . . . . . 2
4 MC34704B 5 Ch. DC/DC Power Management IC . . 3
5 Software Considerations . . . . . . . . . . . . . . . . . . . . . 8
6 Component Selection . . . . . . . . . . . . . . . . . . . . . . . 9
7 Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8 Layout Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9 Layout Considerations . . . . . . . . . . . . . . . . . . . . . 17
10 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . 18
With the info presented here, the i.MX27 can be
supplied so it will work on a basic application on which
low power modes can not be accessed due to the
absence of power gating system on the MC34704B. To
be able to use low power modes, extra circuitry must be
added to the system.
© Freescale Semiconductor, Inc., 2008. All rights reserved.. All rights reserved.
i.MX27 Power Requirements
3
i.MX27 Power Requirements
i.MX27 Power Signal
Symbol
Min.
Typ
Max
Units
Core Voltage Supply (@266MHz)
QVDD
1.2
1.3
1.52
V
Core Voltage Supply (@400MHz)
QVDD
1.38
1.45
1.52
V
RTC, SCC, Separate Supply Voltage
RTCVDD
1.2
-
1.52
V
Analog Supply Voltage: FPMVDD, UPLLVDD, MPLLVDD
VDD
1.35
1.4
1.6
V
OSC32VDD
VOSC32
1.1
-
1.6
V
I/O Supply Voltage, Fast (7, 11, 12, 14, 15)
NVDD_FAST
1.75
-
2.8
V
I/O Supply Voltage, Slow (5, 6, 8, 9, 10, 13, AVDD)
NVDD_SLOW
1.75
-
3.05
V
OSC26VDD
VOSC26
2.68
-
2.875
V
I/O Supply Voltage, DDR (1, 2, 3, 4)
NVDD_DDR
1.75
-
1.9
V
Fuse box read Supply Voltage
FUSE_VDD
1.7
1.875
1.95
V
Fuse box Program Supply Voltage
FUSE_VDD
3
3.15
3.3
V
3.1
i.MX27 Power Up Sequence
The i.MX27/MX27L processor consists of three major sets for power supply voltage named QVDD (core logic
supply), FUSEVDD (analog supply for FUSEBOX), and NVDDVDDA (IO supply). The External Voltage Regulators
and power-on devices must provide the applications processor with a specific sequence of power and resets to
ensure proper operation.
It is important that the applications processor power supplies be powered-up in a certain order to avoid unintentional
fuse blown. QVDD should be powered up before FUSEVDD.
If the core operating frequency is set to 266MHZ and VDDQ supply group is required to be 1.3V, then, an extra
voltage rail is needed to provide the Analog supply Voltage. Otherwise, if Core supply voltage can be set higher or
operating frequency is 400MHz core supply and Analog supply can be sourced from a single power supply at a
typical value of 1.45V.
Noticed that since the maximum operating voltage for the Core voltage group is 1.52V, caution must be taken in
order to have a very tight regulation and avoid overstressing or blowing the microprocessor terminals.
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
2
Freescale Semiconductor
MC34704B 5 Ch. DC/DC Power Management IC
4
MC34704B 5 Ch. DC/DC Power Management IC
The MC34704B is a multi-channel Power Management IC (PMIC) used to address power management needs for
various multimedia application microprocessors. Its ability to provide 5 independent output voltages with a single
input power supply (2.7 and 5.5V) together with its high efficiency, make it ideal for portable devices powered up by
Li-Ion/polymer batteries or for USB powered devices as well.
The MC34704B is housed in a 7x7mm, Pb-free, QFN56 and is capable of operating at a switching frequency of up
to 2MHz. This makes it possible to reduce external component size and to implement full space efficient power
management solutions.
Features
•
•
•
•
•
•
•
•
•
•
•
4.1
5 DC/DC (MC34704B) switching regulators with up to ±2% output voltage accuracy
Dynamic voltage scaling on all regulators
Selectable voltage mode control or current mode control on REG8
I2C programmability
Output under-voltage and over-voltage detection for each regulator
Over-current limit detection and short-circuit protection for each regulator
Thermal limit detection for each regulator
Integrated compensation for REG3 and REG8
5µA maximum shutdown current (All regulators are off, 5.5V VIN)
True cutoff on all of the boost and buck-boost regulators
Pb-free packaging designated by suffix code EP
MC34704B Capabilities
MC34704B Capabilities
Regulator
Output Voltage (V)
Output Current (mA)
Min.
Typ
Max
Typ
Max
Reg2
0.6
2.8/3.3
3.6
200
500
Reg3
0.6
1.2/1.5/1.8
1.8
150
550
Reg4
0.6
1.8/2.5
3.6
100
300
Reg5
0.6
3.3
3.6
150
550
Reg8
5
15
15
15
30
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
Freescale Semiconductor
3
MC34704B 5 Ch. DC/DC Power Management IC
4.2
Interface Diagram
The diagram below shows how the communication pins and power sources must be connected to the i.MX27, and
the output voltage for which each one must be configured.
It is a good practice to place ferrite beads on the REG2 voltage supply in order to avoid noise caused for supplying
three different voltage domains in the i.MX27:
i.MX27
MC34704B
QVDD
REG3 (1.5V)
RTCVDD,
OSC32VDD,
UPLLVDD,
FPMVDD,
MPLLVDD
REG2 (2.8V)
Ferrite Beads
REG4 (1.8V)
NVDD5, 6, 8, 9,
10, 13, AVDD
NVDD7, 11, 12,
14, 15
REG5 (3.3V)
OSC26VDD
REG8
NVDD1-4
N/C
REG2
FUSE_VDD
4.7K
SCL
I2C_CLK_PD18
REG2
4.7K
SDA
I2C_DAT A_
PD17
REG2
10K
RST
POR
Figure 1. Interface Diagram
As can be seen, REG8 of MC34704B is available to supply other peripherals or external circuitry that may require
5 to 15V at 30mA.
RST signal on the MC34704B goes low as soon as regulators 2, 3 and 4 have reached a stable state at their final
value. This indicates the i.MX27 that all the voltages are ready for it to start operating. When this signal goes low,
the i.MX27 restarts all the modules and peripherals to a known state so the system can start its operation.
I2C communication is established through pins SCL and SDA of the MC34704B, which have to be connected to
I2C_CLK_PD18 and I2C_DATA_PD17 of the i.MX27 respectively.
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
4
Freescale Semiconductor
MC34704B 5 Ch. DC/DC Power Management IC
4.3
Power Sequencing
The MC34704B turns on its regulators following this sequence:
•
•
•
REG3
REG2
REG4
Each of the regulators has a soft start time given by a voltage applied to the SS pin. For this application, a 8ms soft
start has to be used, for which a resistor divider must be placed from VDDI to ground, as shown in the following
picture.
Figure 2. Resistor Divider
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
Freescale Semiconductor
5
MC34704B 5 Ch. DC/DC Power Management IC
This is how the startup sequence looks like on the MC34704B:
Figure 3. Sequencing 1
Figure 4. Sequencing 2
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
6
Freescale Semiconductor
MC34704B 5 Ch. DC/DC Power Management IC
The following flow diagram shows how the power pins of the i.MX27 will be turned on according to the power on
sequence of the MC34704B.
REG3
QVDD, RTCVDD, OSC32VDD,
UPLLVDD, FPMVDD, MPLLVDD
REG2
NVDD_SLOW, AVDD
NVDD_FAST,
OSC26VDD
REG4
NVDD_DDR
REG5
FUSEVDD
Figure 5. Flow Diagram
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
Freescale Semiconductor
7
Software Considerations
5
Software Considerations
The MC34704B is programmed through a plain I2C protocol, the I.MX processor should include a firmware driver to
translate the controlling instructions into I2C commands to allow register writing and flag reading for communication
acknowledge. Such driver structure is not defined in this document, instead, it will be discussed only the software
portion concerning the MC34704B As well as the I2C commands needed to interact with the MC34704B.
The Power on process is very straight forward:
•
•
•
If there is a battery insertion, REG3, 2 and 4 will turn on in that order enabling I2C communication protocol
as well as i.MX processor power on sequence; in such case, the MC34704B will set the COLDF flag to
acknowledge that power on was a result of battery insertion. During the power on process, the MPU should
acknowledge that power up was a result of a battery insertion and then send an ALLOFF I2C command to
disable the power supply and shut down until a desired hardware Power on is present.
If the ON/OFF terminal sees a falling edge, then the MC34704B start a power on cycle ramping up regulator
3, 2 and 4. In this case, the COLDF bit is not set high, thus, when the i.MX processor read this register it
acknowledge it is an actual power up and start a full power on sequence. By this time, PMIC is providing
1.45V, 1.8V and 2.7V, and the processor can provide following configuration commands:
•
REG2, REG3, REG4 OV/UV response
•
REG5 OV/UV response
•
REG5 Soft start timing (if desired)
At this point the processor can send a REG5 ON/OFF instruction via I2C when the 3.15V rail is required.
From now on, all voltage rails can be dynamically scaled up or down using the DVS register and processor
can send a power off command when required.
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
8
Freescale Semiconductor
Component Selection
6
6.1
Component Selection
Inductors
VG serves as internal supply for all gate drivers within the MC34704B, L1 dimensions depends directly on the
inductance value and the saturation current ISAT, chose and inductor with inductance value between 2.2 to 4.7uH,
and ISAT around 150mA.
To select Inductors L2 - L5, choose inductance values between 3.0 to 4.7uH, with an ISAT of approximately twice
the maximum current to be demanded from each regulator. As approximate values, the regulators will be supplying:
Regulator
Current (mA)
Reg2
30
Reg3
400
Reg4
60
Reg5
60
Note: make sure to use power inductor and not choke inductors for these components to assure correct performance of the
MC34704B.
6.2
Capacitors and Resistors
Choose capacitors with at least twice the voltage rating as the maximum voltage that the capacitor will be exposed
to. for the output inductors, use capacitance values from 10 to 22uF.
Resistors are very straight forward to choose, the only important thing while calculating the output voltage of each
regulator, is to take the resistor accuracy into consideration specially on those voltage rails where the output voltage
is close to the maximum voltage rating of the I.MX terminal; a miscalculation of the resistor accuracy may cause the
output voltage to go slightly above the maximum allowed overstressing or damaging the processor terminal in the
application. Use 1% or smaller tolerance resistors to have a good control of output voltage values.
Note: for more details on external component calculation, please refer to the MC34704B data sheet that can be
found at www.freecale.com.
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
Freescale Semiconductor
9
Schematic
Schematic
VOUT5 = 3.3 V
@ 500 mA max
VOUT2 = 2.7 V
@ 500 mA max
VOUT5
VOUT2
68K
R240
R64
R81
68K
C176
130PF
R61
C170
2.55K
L10
4.7UH
R83
C114
1.0UF
C177
22UF
GND
R239
19.6K
GND
1
60.4K
L7
4.7UH
C103
1.0UF
R238
4.3K
C165
22UF
2
GND
150PF
1
15K
2
7
C118
1.0UF
C232
C231
R241
73.2K
68PF
1000PF
C109 GND
1.0UF
VOUT4 = 1.8 V
@ 300 mA max
VCC
VOUT4
VCC
11
VCC
1
12
13
L8
4.7UH
43
COMP2
45
46
44
FB2
BT2D
PVIN2
48
47
SW2D
49
SW2U
VOUT2
51
52
53
50
SW5U
VOUT5
SW5D
BT5D
PVIN5
54
56
FB4
NC8
COMP4
NC7
BT3
NC6
PVIN3
NC5
SW3
NC4
VOUT3
NC3
FB3
NC2
PGND
R82
10K
42
41
VDDI
40
39
38
VCC
37
C117
1.0UF
C120
36
1.0UF
35
34
GND
GND
GND
33
32
31
30
29
57
28
27
26
25
24
23
22
21
20
19
18
MC34704BEP
C167
22UF
17
VOUT3
16
VOUT3 = 1.45 V
@ 550 mA max
15
2
SS
14
NC9
NC1
0.01uF
BT4U
RST
10
AGND
SDA
GND
VIN
SW4U
SCL
9
C166
VOUT4
BT1
8
C172 0.01uF
150PF
VDDI
NC0
7
C173
LION
SW4D
VG
2
6
BT2U
PVIN4
SW1
5
VCC
R62
470K
ONOFF
SWBL
L9
4.7UH
R77
82K
R53
34K
BT4D
VOUTBL
4
BT5U
BTBL
3
0.01uF
1
130PF
GND
2
VCC
FBBL
C171
FB5
1
C169
COMP5
R242
68K
R47
2.55K
FREQ
C168
22UF
55
VCC
U13
R71
68K
GND
VOUT2
R79
GND
22K
10K
R235
R234
VDDI
10K
POR
R60
45.3K
GND
VOUT2
VIN FILTERING AND DECOUPLING
VCC
1
1
GND
R68
4.7K
R80
4.7K
I2C_DATA
2
GND
L6
3.3UH
D10
MBR230LSFT1G
2
C121
22UF
I2C_CLK
I2C LINES
FOR MC34704
PMIC CONTROL
C101
1.0UF
Figure 6. MC34704B Schematic
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
10
Freescale Semiconductor
Layout Example
8
Layout Example
The following is an example of a layout for the MC34704B proposed to work with the I.MX27 Microprocessor, total
area is not 100% optimized in order to show the output voltage rails and the communication lines on the power
management solution. Freescale proposed layout is designed in 4 layers, using top and bottom layer for routing and
component placing and Inner1 and Inner2 layers for Power and Ground respectively. In this document only Top and
Bottom layers are presented, since the inner layers are full planes as described above.
Figure 7. Top Copper
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
Freescale Semiconductor
11
Layout Example
Figure 8. Top Silk Screen
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
12
Freescale Semiconductor
Layout Example
Figure 9. Top Copper and Silk Screen
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
Freescale Semiconductor
13
Layout Example
Figure 10. Bottom Copper
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
14
Freescale Semiconductor
Layout Example
Figure 11. Bottom Silk Screen.
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
Freescale Semiconductor
15
Layout Example
Figure 12. Bottom Copper and Silk Screen.
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
16
Freescale Semiconductor
Layout Considerations
9
Layout Considerations
•
•
•
•
•
•
•
Create a Ground plane layer and tie it to ground signals with vias
Place Test vias as close as possible to the IC to ensure a good measurement value
PVIN, VIN, VOUT signals have to be tracked with a widely and straight copper area
Never trace the Feedback signal in parallel to the SW signal
Ensure the SW Inductor is placed as close as possible to its pads
SW track has to be as thin and short as possible
Make sure the I/O connectors are capable to manage the Load current
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
Freescale Semiconductor
17
Revision History
10 Revision History
Revision
1.0
Date
12/2008
Description Of Changes
• Initial Release
Powering the i.MX27 with the 5 Channel MC34704B IC, Rev. 1.0
18
Freescale Semiconductor
How to Reach Us:
Home Page:
www.freescale.com
Web Support:
http://www.freescale.com/support
USA/Europe or Locations Not Listed:
Freescale Semiconductor, Inc.
Technical Information Center, EL516
2100 East Elliot Road
Tempe, Arizona 85284
+1-800-521-6274 or +1-480-768-2130
www.freescale.com/support
Europe, Middle East, and Africa:
Freescale Halbleiter Deutschland GmbH
Technical Information Center
Schatzbogen 7
81829 Muenchen, Germany
+44 1296 380 456 (English)
+46 8 52200080 (English)
+49 89 92103 559 (German)
+33 1 69 35 48 48 (French)
www.freescale.com/support
Japan:
Freescale Semiconductor Japan Ltd.
Headquarters
ARCO Tower 15F
1-8-1, Shimo-Meguro, Meguro-ku,
Tokyo 153-0064
Japan
0120 191014 or +81 3 5437 9125
[email protected]
Asia/Pacific:
Freescale Semiconductor Hong Kong Ltd.
Technical Information Center
2 Dai King Street
Tai Po Industrial Estate
Tai Po, N.T., Hong Kong
+800 2666 8080
[email protected]
For Literature Requests Only:
Freescale Semiconductor Literature Distribution Center
P.O. Box 5405
Denver, Colorado 80217
1-800-441-2447 or 303-675-2140
Fax: 303-675-2150
[email protected]
AN3809
Rev. 1.0
12/2008
Information in this document is provided solely to enable system and software
implementers to use Freescale Semiconductor products. There are no express or
implied copyright licenses granted hereunder to design or fabricate any integrated
circuits or integrated circuits based on the information in this document.
Freescale Semiconductor reserves the right to make changes without further notice to
any products herein. Freescale Semiconductor makes no warranty, representation or
guarantee regarding the suitability of its products for any particular purpose, nor does
Freescale Semiconductor assume any liability arising out of the application or use of any
product or circuit, and specifically disclaims any and all liability, including without
limitation consequential or incidental damages. “Typical” parameters that may be
provided in Freescale Semiconductor data sheets and/or specifications can and do vary
in different applications and actual performance may vary over time. All operating
parameters, including “Typicals”, must be validated for each customer application by
customer’s technical experts. Freescale Semiconductor does not convey any license
under its patent rights nor the rights of others. Freescale Semiconductor products are
not designed, intended, or authorized for use as components in systems intended for
surgical implant into the body, or other applications intended to support or sustain life,
or for any other application in which the failure of the Freescale Semiconductor product
could create a situation where personal injury or death may occur. Should Buyer
purchase or use Freescale Semiconductor products for any such unintended or
unauthorized application, Buyer shall indemnify and hold Freescale Semiconductor and
its officers, employees, subsidiaries, affiliates, and distributors harmless against all
claims, costs, damages, and expenses, and reasonable attorney fees arising out of,
directly or indirectly, any claim of personal injury or death associated with such
unintended or unauthorized use, even if such claim alleges that Freescale
Semiconductor was negligent regarding the design or manufacture of the part.
Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc.
All other product or service names are the property of their respective owners.
© Freescale Semiconductor, Inc., 2008. All rights reserved.