DATASHEET

NOT RECOMMENDED FOR NEW DESIGNS
RECOMMENDED REPLACEMENT PART
ZL2102
3A Digital-DC Synchronous Step-Down DC/DC
Converter
ZL2103
Features
The ZL2103 is an innovative power conversion and
management IC that combines an integrated synchronous
step-down DC/DC converter with key power management
functions in a small package, resulting in a flexible and
integrated solution.
• Integrated MOSFET switches
The ZL2103 can provide an output voltage from 0.54V to 5.5V
(with margin) from an input voltage between 4.5V and 14V.
Internal low rDS(ON) synchronous power MOSFETs enable the
ZL2103 to deliver continuous loads up to 3A with high
efficiency. An internal Schottky bootstrap diode reduces
discrete component count. The ZL2103 also supports phase
spreading to reduce system input capacitance.
• I2C/SMBus interface, PMBus compatible
Power management features such as digital soft-start delay
and ramp, sequencing, tracking, and margining can be
configured by simple pin-strapping or through an on-chip serial
port. The ZL2103 uses the PMBus™ protocol for
communication with a host controller and the Digital-DC bus
for interoperability between other Zilker Labs devices.
• Industrial control equipment
• 3A continuous output current
• ±1% output voltage accuracy
• Snapshot™ parametric capture
• Internal non-volatile memory (NVM)
Applications*(see page 27)
• Telecom, Networking, Storage equipment
• Test and Measurement equipment
• 5V and 12V distributed power systems
Related Literature
• See AN2010 “Thermal and Layout Guidelines for DigitalDC™ Products”
• See AN2033 “Zilker Labs PMBus Command Set-DDC
Products PMBus Command Set”
• See AN2035 “Compensation Using CompZL™”
100
VOUT = 3.3V
EFFICIENCY (%)
90
80
70
60
50
40
0.0
VIN = 12V
fSW = 200kHz
L = 6µH
0.5
1.0
1.5
2.0
2.5
3.0
IOUT (A)
FIGURE 1. ZL2103 EFFICIENCY
May 3, 2011
FN6966.5
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas Inc. 2009-2011. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
ZL2103
Typical Application Circuit
The following application circuit represents a typical
implementation of the ZL2103. For PMBus operation, it is
recommended to tie the enable pin (EN) to SGND.
F.B.‡
CRA
4.7µF
C25
10µF
VDDP 29
VDDP 28
VR 31
VRA 32
DDC 34
1 PG
VDDS 30
PGOOD
CDD
2.2µF
CR
4.7µF
V2P5 33
EN 36
DDC Bus
ENABLE
MGN 35
†
VDDP 27
2 DGND
BST 26
3 SYNC
SW 25
4 VSET
SW 24
ZL2103
5 SA
SW 23
6 SCL
7 SDA
SW 21
8 SALRT
SW 20
CB
47nF
LOUT
2.2µH
VOUT
3.3V
COUT
150µF
18 PGND
17 PGND
PGND 19
16 PGND
14 SGND
12 VTRK
13 VSEN
11 SS
10 CFG
9 FC
ePAD
(SGND)
CIN
100µF
SW 22
15 PGND
I2C/
SMBus††
VIN
12V
Notes:
‡
Ferrite bead is optional for input noise suppression.
†
The DDC bus pull-up resistance will vary based on the capacitive loading of the bus, including the number of devices
 default value, assuming a maximum of 100 pF per device, provides the necessary 1 µs pull-up rise
connected. The 10 k
time. Please refer to the Digital-DC Bus section for more details.
††
The I2C/SMBus pull-up resistance will vary based on the capacitive loading of the bus, including the number of devices
connected. Please refer to the I2C/SMBus specifications for more details.
FIGURE 2. 12V TO 3.3V/3A APPLICATION CIRCUIT (5ms SS DELAY, 5ms SS RAMP)
Block Diagram
2.5V
LDO
5V
LDO
7V
LDO
VDDP
VDDS
VR
EN
VRA
V2P5
VIN
BST
PG
VTRK
SALRT
SMBus
SCL
DDC Bus
SA
SDA
DDC
PWM
Control
&
Drivers
SW
VOUT
VSEN
NVM
PGND
Power
Mgmt
SYNC
MGN
VSET
CFG
SS
FIGURE 3. BLOCK DIAGRAM
2
FN6966.5
May 3, 2011
ZL2103
Pin Configuration
28
29
31
30
32
34
33
1
27
2
26
ZL2103
3
4
25
24
36-Pin QFN
6 x 6 mm
5
6
23
22
7
Exposed Paddle
8
Connect to SGND
21
20
9
18
17
16
15
14
12
13
VDDP
BST
SW
SW
SW
SW
SW
SW
PGND
CFG
SS
VTRK
VSEN
SGND
PGND
PGND
PGND
PGND
11
19
10
PG
DGND
SYNC
VSET
SA
SCL
SDA
SALRT
FC
35
36
EN
MGN
DDC
V2P5
VRA
VR
VDDS
VDDP
VDDP
ZL2103
(36 LD QFN)
TOP VIEW
FIGURE 4.
Pin Descriptions
PIN
LABEL
TYPE
(Note 1)
1
PG
O
2
DGND
PWR
3
SYNC
I/O, M
(Note 2)
4
VSET
I, M
Output voltage select pin. Used to set VOUT set-point and VOUT max.
5
SA
I, M
Serial address select pin. Used to assign unique SMBus address to each IC.
6
SCL
I/O
Serial clock. Connect to external host interface.
7
SDA
I/O
Serial data. Connect to external host interface.
8
SALRT
O
9
FC
I, M
Loop compensation select pin. Used to set loop compensation.
10
CFG
I, M
Configuration pin. Used to control the SYNC pin, sequencing and enable tracking.
11
SS
I, M
Soft-start pin. Used to set the ramp delay and ramp time, sets UVLO and configure tracking.
12
VTRK
I
Track sense pin. Used to track an external voltage source.
13
VSEN
I
Output voltage positive feedback sensing pin.
14
SGND
PWR
Common return for analog signals. Connect to low impedance ground plane.
15, 16, 17,
18, 19
PGND
PWR
Power ground. Common return for internal switching MOSFETs. Connect to low impedance ground plane.
20, 21, 22,
23, 24, 25
SW
I/O
26
BST
PWR
Bootstrap voltage for level-shift driver (referenced to SW).
27, 28, 29
VDDP
PWR
Bias supply voltage for internal switching MOSFETs (return is PGND).
30
VDDS
PWR
IC supply voltage (return is SGND).
3
DESCRIPTION
Power-good. This pin transitions high 100ms after output voltage stabilizes within regulation band.
Selectable open drain or push-pull output. Factory default is open drain.
Digital ground. Common return for digital signals. Connect to low impedance ground plane.
Clock synchronization pin. Used to set switching frequency of internal clock or for synchronization to
external frequency reference.
Serial alert. Connect to external host interface if desired.
Switching node (level-shift common).
FN6966.5
May 3, 2011
ZL2103
Pin Descriptions (Continued)
PIN
LABEL
TYPE
(Note 1)
31
VR
PWR
Regulated bias from internal 7V low-dropout regulator (return is PGND). Decouple with a 4.7µF capacitor to
PGND.
32
VRA
PWR
Regulated bias from internal 5V low-dropout regulator for internal analog circuitry (return is SGND).
Decouple with a 4.7µF capacitor to SGND.
33
V2P5
PWR
Regulated bias from internal 2.5V low-dropout regulator for internal digital circuitry (return is DGND).
Decouple with a 10µF capacitor.
34
DDC
I/O
35
MGN
I
Margin pin. Used to enable margining of the output voltage.
36
EN
I
Enable pin. Used to enable the device (active high).
ePad
SGND
PWR
DESCRIPTION
Digital-DC Bus (open drain). Interoperability between Zilker Labs devices.
Exposed thermal pad. Common return for analog signals. Connect to low impedance ground plane.
NOTES:
1. I = Input, O = Output, PWR = Power or Ground, M = Multi-mode pins. Please refer to Section “Multi-mode Pins” on page 12.
2. The SYNC pin can be used as a logic pin, a clock input or a clock output.
Ordering Information
PART NUMBER
(Notes 4, 5)
PART
MARKING
TEMP RANGE
(°C)
PACKAGE
(Pb-free)
PKG.
DWG. #
ZL2103ALAF
2103
-40 to +85
36 Ld 6mmx6mm QFN
L36.6x6C
ZL2103ALAFT (Note 3)
2103
-40 to +85
36 Ld 6mmx6mm QFN
L36.6x6C
ZL2103ALAFTK (Note 3)
2103
-40 to +85
36 Ld 6mmx6mm QFN
L36.6x6C
ZL2103EVAL1Z
Evaluation Board
NOTES:
3. Please refer to TB347 for details on reel specifications.
4. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte
tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil
Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.
5. For Moisture Sensitivity Level (MSL), please see device information page for ZL2103. For more information on MSL please see techbrief TB363.
4
FN6966.5
May 3, 2011
ZL2103
Table of Contents
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Thermal Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Typical Performance Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
ZL2103 Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Digital-DC Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Power Conversion Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Power Management Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Multi-mode Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Power Conversion Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Internal Bias Regulators and Input Supply Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
High-side Driver Boost Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Output Voltage Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Start-up Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Soft-start Delay and Ramp Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Power-good (PG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Switching Frequency and PLL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Component Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Current Sensing and Current Limit Threshold Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Loop Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Driver Dead-time Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Power Management Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Input Undervoltage Lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Output Overvoltage Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Output Pre-Bias Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Output Overcurrent Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Thermal Overload Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Voltage Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Voltage Margining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
I2C/SMBus Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
I2C/SMBus Device Address Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Digital-DC Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Phase Spreading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Output Sequencing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Fault Spreading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Monitoring via I2C/SMBus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Snapshot™ Parametric Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Non-Volatile Memory and Device Security Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Package Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5
FN6966.5
May 3, 2011
ZL2103
Absolute Maximum Ratings
Thermal Information
DC Supply Voltage for VDDP, VDDS Pins . . . . . . . . . . . . . . . . . . -0.3V to 17V
High-Side Supply Voltage for BST Pin. . . . . . . . . . . . . . . . . . . . . -0.3V to 25V
High-Side Boost Voltage for BST - SW Pins . . . . . . . . . . . . . . . . . -0.3V to 8V
Internal MOSFET Reference for VR Pin . . . . . . . . . . . . . . . . . . -0.3V to 8.5V
Internal Analog Reference for VRA Pin . . . . . . . . . . . . . . . . . . -0.3V to 6.5V
Internal 2.5 V Reference for V2P5 Pin. . . . . . . . . . . . . . . . . . . . . -0.3V to 3V
Logic I/O Voltage for EN, CFG, DDC, FC, MGN, PG, SDA, SCL,
SA, SALRT, SS, SYNC, VTRK, VSET, VSEN Pins . . . . . . . . . . . . . . . . -0.3V to 6.5V
Ground Differential for DGND - SGND,
PGND - SGND Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±0.3V
MOSFET Drive Reference Current for for VR Pin
Internal Bias Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20mA
Switch Node Current for SW Pin
Peak (Sink Or Source) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5A
ESD Rating
Human Body Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2kV
Machine Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500V
Latch-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Tested to JESD78
Thermal Resistance (Typical)
JA (°C/W) JC (°C/W)
36 Ld QFN (Notes 6, 7) . . . . . . . . . . . . . . . .
28
1
Junction Temperature Range . . . . . . . . . . . . . . . . . . . . . . .-55°C to +150°C
Storage Temperature Range. . . . . . . . . . . . . . . . . . . . . . . .-55°C to +150°C
Dissipation Limits (Note 8)
TA = +25°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5W
TA = +55°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5W
TA = +85°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4W
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
Recommended Operating Conditions
Input Supply Voltage Range, VDDP, VDDS (See Figure 13)
VDDS tied to VR, VRA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5V to 5.5V
VDDS tied to VR, VRA Floating . . . . . . . . . . . . . . . . . . . . . . . . 5.5V to 7.5V
VR, VRA Floating. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.5V to 14V
Output Voltage Range, VOUT (Note 9) . . . . . . . . . . . . . . . . . . . . 0.54V to 5.5V
Operating Junction Temperature Range, TJ . . . . . . . . . . . . .-40°C to +125°C
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product
reliability and result in failures not covered by warranty.
NOTES:
6. JA is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See Tech
Brief TB379.
7. For JC, the “case temp” location is the center of the exposed metal pad on the package underside.
8. Thermal impedance depends on layout.
9. Includes margin limits.
Electrical Specifications
VDDP = VDDS = 12V, TA = -40°C to +85°C unless otherwise noted. (Note 10) Typical values are at TA = +25°C.
Boldface limits apply over the operating temperature range, -40°C to +85°C.
MIN
(Note 20)
TYP
MAX
(Note 20)
UNIT
fSW = 200kHz, no load
-
11
20
mA
fSW = 1MHz, no load
-
15
30
mA
IDDS Shutdown Current
EN = 0V, No I2C/SMBus activity
-
0.6
1
mA
VR Reference Output Voltage
VDD > 8V, IVR < 10mA
6.5
7.0
7.5
V
VRA Reference Output Voltage
VDD > 5.5V, IVRA < 20mA
4.5
5.1
5.5
V
V2P5 Reference Output Voltage
IV2P5 < 20mA
2.25
2.5
2.75
V
-
-
3
A
0.6
-
5.0
V
PARAMETER
CONDITIONS
Input and Supply Characteristics
IDD Supply Current
Output Characteristics
Output Current
IRMS, Continuous
Output Voltage Adjustment Range (Note 11)
VIN > VOUT
Output Voltage Setpoint Resolution
Set using resistors
-
10
-
mV
Set using I2C/SMBus
-
±0.025
-
% FS
(Note 12)
Vsen Output Voltage Accuracy
Includes line, load, temp
-1
-
1
%
Vsen Input Bias Current
VSEN = 5.5V
-
110
200
µA
Soft-start Delay Duration Range (Note 13)
Set using SS pin or resistor
2
-
20
ms
0.002
-
500
s
Set using
6
I2C/SMBus
FN6966.5
May 3, 2011
ZL2103
Electrical Specifications
VDDP = VDDS = 12V, TA = -40°C to +85°C unless otherwise noted. (Note 10) Typical values are at TA = +25°C.
Boldface limits apply over the operating temperature range, -40°C to +85°C. (Continued)
MIN
(Note 20)
TYP
MAX
(Note 20)
UNIT
Turn-on delay (precise mode)
(Notes 13, 14)
-
±0.25
-
ms
Turn-on delay (normal mode) (Note 15)
-
-0.25/+4
-
ms
Turn-off delay (Note 15)
-
-0.25/+4
-
ms
Set using SS pin or resistor
2
-
20
ms
0
-
200
ms
-
100
–
µs
-250
-
250
nA
-
-
0.8
V
-
1.4
-
V
2.0
-
-
V
PARAMETER
CONDITIONS
Soft-start Delay Duration Accuracy
Soft-start Ramp Duration Range
Set using
I2C/SMBus
Soft-start Ramp Duration Accuracy
Logic Input/output Characteristics
Logic Input Leakage Current
Digital pins
Logic input low, VIL
Logic input OPEN (N/C)
Multi-mode logic pins
Logic Input High, VIH
Logic Output Low, VOL
IOL  4mA
-
-
0.4
V
Logic Output High, VOH
IOH  -2mA
2.25
-
-
V
-
-
4.5
A
200
-
1000
kHz
Oscillator and Switching Characteristics
Switch Node Current, ISW
Peak (source or sink) (Note 16)
Switching Frequency Range
Switching Frequency Set-point Accuracy
Predefined settings (Table 9)
-5
-
5
%
PWM Duty Cycle (max)
Factory default (Note 17)
-
-
95
(Note 18)
%
150
-
-
ns
SYNC Pulse Width (min)
Input Clock Frequency Drift Tolerance
External clock source
-13
-
13
%
rDS(ON) of High Side N-channel FETs
ISW = 3A, VGS = 6.5V
-
60
85
m
rDS(ON) of Low Side N-channel FETs
ISW = 3A, VGS = 12V
-
43
65
m
VTRK Input Bias Current
VTRK = 5.5V
-
110
200
µA
VTRK Tracking Ramp Accuracy
100% Tracking, VOUT - VTRK
-100
-
100
mV
VTRK Regulation Accuracy
100% Tracking, VOUT - VTRK
-1
-
1
%
Configurable via I2C/SMBus
2.85
-
16
V
-150
-
150
mV
-
3
-
%
0
-
100
%
-
-
2.5
µs
Tracking
Fault Protection Characteristics
UVLO Threshold Range
UVLO Set-point Accuracy
UVLO Hysteresis
Factory default
Configurable via
I2C/SMBus
UVLO Delay
Power-good VOUT Threshold
Factory default
-
90
-
% VOUT
Power-good VOUT Hysteresis
Factory default
-
5
-
%
Power-good Delay
Using pin-strap or resistor
2
-
20
ms
0
-
500
s
Configurable via
7
I2C/SMBus
)
FN6966.5
May 3, 2011
ZL2103
Electrical Specifications
VDDP = VDDS = 12V, TA = -40°C to +85°C unless otherwise noted. (Note 10) Typical values are at TA = +25°C.
Boldface limits apply over the operating temperature range, -40°C to +85°C. (Continued)
PARAMETER
CONDITIONS
VSEN Undervoltage Threshold
VSEN Overvoltage Threshold
MIN
(Note 20)
TYP
MAX
(Note 20)
UNIT
Factory default
-
85
-
% VOUT
Configurable via I2C/SMBus
0
-
110
% VOUT
Factory default
-
115
-
% VOUT
Configurable via I2C/SMBus
0
-
115
% VOUT
VSEN Undervoltage Hysteresis
-
5
-
% VOUT
VSEN Undervoltage/Overvoltage Fault Response
Time
Factory default
-
16
-
µs
Configurable via I2C/SMBus
5
-
60
µs
Peak Current Limit Threshold
Factory default
-
-
4.5
A
0.2
-
4.5
A
-
±10
-
% FS
(Note 12)
Factory default
-
5
-
tSW
(Note 19)
Configurable via I2C/SMBus
1
-
32
tSW
(Note 19)
-
125
-
°C
-40
-
125
°C
-
15
-
°C
Configurable via I2C/SMBus
Current Limit Set-point Accuracy
Current Limit Protection Delay
Thermal Protection Threshold (Junction Temperature) Factory default
Configurable via
I2C/SMBus
Thermal Protection Hysteresis
NOTES:
10. Refer to Safe Operating Area in Figure 8 and thermal design guidelines in AN2010.
11. Does not include margin limits.
12. Percentage of Full Scale (FS) with temperature compensation applied.
13. The device requires a delay period following an enable signal and prior to ramping its output. Precise timing mode limits this delay period to approx
2ms, where in normal mode it may vary up to 4ms.
14. Precise ramp timing mode is only valid when using EN pin to enable the device rather than PMBus enable. Precise ramp timing mode is automatically
disabled for a self-enabled device (EN pin tied high).
15. The devices may require up to a 4ms delay following the assertion of the enable signal (normal mode) or following the
de-assertion of the enable signal. Precise mode requires Re-Enable delay = TOFF+TFALL+10µs.
16. Switch node current should not exceed IRMS of 3A.
17. Factory default is the initial value in firmware. The value can be changed via PMBus commands.
18. Maximum duty cycle is limited by the equation MAX_DUTY(%) = [1 - (150×10-9 × fSW)] × 100 and not to exceed 95%.
19. tSW = 1/fSW, where fSW is the switching frequency.
20. Compliance to datasheet limits is assured by one or more methods: production test, characterization and/or design.
8
FN6966.5
May 3, 2011
ZL2103
Typical Performance Curves
1.4
1.4
1.3
1.3
NORMALIZED rDS(ON)
NORMALIZED rDS(ON)
For some applications, ZL2103 operating conditions (input voltage, output voltage, switching
frequency, temperature) may require de-rating to remain within the Safe Operating Area (SOA). VIN = VDDP = VDDS, TJ = +125°C.
1.2
1.1
1.0
0.9
0.8
0
25
50
75
1.2
1.1
1.0
0.9
0.8
100
0
25
50
TJ (°C)
TJ (°C)
FIGURE 5. LOW-SIDE rDS(ON) vs TJ NORMALIZED FOR
TJ = +25°C (VDDS = 12V, IDRAIN = 0.3A)
0.95
65
0.90
VOUT/VIN (V)
rDS(ON) (mΩ)
55
TJ = +80°C
50
TJ = +50°C
40
7
8
0.80
0.75
0.70
0.65
TJ = +25°C
6
VOUT MAY NOT EXCEED
5.5V AT ANY TIME
0.85
TJ = +110°C
45
100
FIGURE 6. HIGH-SIDE rDS(ON) vs TJ NORMALIZED FOR
TJ = +25°C (VDDS = 12V, BST – SW = 6.5V,
IDRAIN = 0.3A)
70
60
75
9
10
11
12
VDDS (V)
FIGURE 7. LOW-SIDE rDS(ON) vs VDDS WITH TJ
9
13
0.60
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
fSW (MHz)
FIGURE 8. MAXIMUM CONVERSION RATIO,
TJ +125°C
FN6966.5
May 3, 2011
ZL2103
ZL2103 Overview
VIN
Digital-DC Architecture
The ZL2103 is an innovative mixed-signal power conversion and
power management IC based on Zilker Labs patented Digital-DC
technology that provides an integrated, high performance stepdown converter for point of load applications. The ZL2103
integrates all necessary PWM control circuitry as well as low
rDS(ON) synchronous power MOSFETs to provide an extremely
small solution for supplying load currents up to 3A.
Its unique PWM loop utilizes an ideal mix of analog and digital
blocks to enable precise control of the entire power conversion
process with no software required, resulting in a very flexible
device that is also very easy to use. An extensive set of power
management functions are fully integrated and can be
configured using simple pin connections. The user configuration
can be saved in an internal non-volatile memory (NVM).
Additionally, all functions can be configured and monitored via
the SMBus hardware interface using standard PMBus
commands, allowing ultimate flexibility.
CIN
LDO
DB
QH
CB
L1
VOUT
PWM
QL
COUT
ZL
FIGURE 9. SYNCHRONOUS BUCK CONVERTER
Once enabled, the ZL2103 is immediately ready to regulate
power and perform power management tasks with no
programming required. Advanced configuration options and realtime configuration changes are available via the I2C/SMBus
interface if desired and continuous monitoring of multiple
operating parameters is possible with minimal interaction from a
host controller. Integrated sub-regulation circuitry enables single
supply operation from any external supply between 4.5V and 14V
with no secondary bias supplies needed. The ZL2103 can also be
configured to operate from a 3.3V or 5V standby supply when the
main power rail is not present, allowing the user to configure
and/or read diagnostic information from the device when the
main power has been interrupted or is disabled.
The ZL2103 can be configured by simply connecting its pins
according to the tables provided in the following sections.
Additionally, a comprehensive set of application notes are
available to help simplify the design process. An evaluation
board is also available to help the user become familiar with the
device. This board can be evaluated as a standalone platform
using pin configuration settings. A Windows™-based GUI is also
provided to enable full configuration and monitoring capability
via the I2C/SMBus interface using an available computer and the
included USB cable.
Power Conversion Overview
The ZL2103 operates as a voltage-mode, synchronous buck
converter with a selectable constant frequency pulse width
modulator (PWM) control scheme. The ZL2103 integrates dual
low rDS(ON) synchronous MOSFETs to minimize the circuit
footprint.
Figure 9 illustrates the basic synchronous buck converter
topology showing the primary power train components. This
converter is also called a step-down converter, as the output
voltage must always be lower than the input voltage.
10
FN6966.5
May 3, 2011
ZL2103
INPUT VOLTAGE BUS
VTRK
VSET
POWER MANAGEMENT
DIGITAL
DIGITAL
COMPENSATOR
COMPENSATOR
FC
BST
LDO
NVM
ISENSE
HS FET
DRIVER
D-PWM
SYNC
GEN
SYNC
VDDP
SS
VDDS
EN MGN CFG
PG
>
VRA
VR
>
SW
VOUT
LS FET
DRIVER
PLL

ADC
-
+
ISENSE
ADC
RESET
REF
DDC
SALRT
SDA
SCL
SA
VDD
VSEN
MUX
ADC
COMMUNICATION
TEMP
SENSOR
FIGURE 10. ZL2103 BLOCK DIAGRAM
VOUT
VIN
IL PK
(EQ. 1)
During time D, QH is on and VIN – VOUT is applied across the
inductor. The output current ramps up as shown in Figure 11.
When QH turns off (time 1-D), the current flowing in the inductor
must continue to flow from the ground up through QL, during which
the current ramps down. Since the output capacitor COUT exhibits
low impedance at the switching frequency, the AC component of the
inductor current is filtered from the output voltage so the load sees
nearly a DC voltage.
The maximum conversion ratio is shown in Figure 9. Typically,
buck converters specify a maximum duty cycle that effectively
limits the maximum output voltage that can be realized for a
given input voltage and switching frequency. This duty cycle limit
ensures that the low-side MOSFET is allowed to turn on for a
minimum amount of time during each switching cycle, which
enables the bootstrap capacitor to be charged up and provide
adequate gate drive voltage for the high-side MOSFET.
11
Voltage
(V)
D
VIN - VOUT
IO
0
Current (A)
The ZL2103 integrates two N-channel power MOSFETs; QH is the
top control MOSFET and QL is the bottom synchronous MOSFET.
The amount of time that QH is on as a fraction of the total
switching period is known as the duty cycle D, which is described
by Equation 1:
ILV
-VOUT
D
1-D
Time
FIGURE 11. INDUCTOR WAVEFORM
FN6966.5
May 3, 2011
ZL2103
In general, the size of components L1 and COUT as well as the
overall efficiency of the circuit are inversely proportional to the
switching frequency, fSW. Therefore, the highest efficiency circuit
may be realized by switching the MOSFETs at the lowest possible
frequency; however, this will result in the largest component size.
Conversely, the smallest possible footprint may be realized by
switching at the fastest possible frequency but this gives a
somewhat lower efficiency. Each user should determine the
optimal combination of size and efficiency when determining the
switching frequency for each application.
The block diagram for the ZL2103 is illustrated in Figure 10. In this
circuit, the target output voltage is regulated by connecting the VSEN
pin directly to the output regulation point. The VSEN signal is then
compared to an internal reference voltage that had been set to the
desired output voltage level by the user. The error signal derived from
this comparison is converted to a digital value with an analog to digital
(A/D) converter. The digital signal is also applied to an adjustable
digital compensation filter and the compensated signal is used to
derive the appropriate PWM duty cycle for driving the internal
MOSFETs in a way that produces the desired output.
Power Management Overview
The ZL2103 incorporates a wide range of configurable power
management features that are simple to implement without
additional components. Also, the ZL2103 includes circuit
protection features that continuously safeguard the device and
load from damage due to unexpected system faults. The ZL2103
can continuously monitor input voltage, output voltage/current
and internal temperature. A Power-good output signal is also
included to enable power-on reset functionality for an external
processor.
All power management functions can be configured using either
pin configuration techniques (see Figure 12) or via the
I2C/SMBus interface. Monitoring parameters can also be
pre-configured to provide alerts for specific conditions. See
Application Note AN2033 for more details on SMBus monitoring.
Multi-mode Pins
In order to simplify circuit design, the ZL2103 incorporates
patented multi-mode pins that allow the user to easily configure
many aspects of the device without programming. Most power
management features can be configured using these pins. The
multi-mode pins can respond to four different connections, as
shown in Table 1. These pins are sampled when power is applied
or by issuing a PMBus Restore command (see Application Note
AN2033).
PIN-STRAP SETTINGS
This is the simplest method, as no additional components are
required. Using this method, each pin can take on one of three
possible states: LOW, OPEN, or HIGH. These pins can be
connected to the V2P5 pin for logic HIGH settings as this pin
provides a regulated voltage higher than 2V. Using a single pin
one of three settings can be selected.
12
TABLE 1. MULTI-MODE PIN CONFIGURATION
PIN TIED TO
VALUE
LOW
(Logic LOW)
< 0.8VDC
OPEN
(N/C)
No connection
HIGH
(Logic HIGH)
> 2.0VDC
Resistor to SGND
Set by resistor value
Logic
high
Open
ZL
ZL
Multi- mode Pin
Multi- mode Pin
RSET
Logic
low
Pinstrap
Settings
Resistor
Settings
FIGURE 12. PIN-STRAP AND RESISTOR SETTING EXAMPLES
RESISTOR SETTINGS
This method allows a greater range of adjustability when
connecting a finite value resistor (in a specified range) between
the multi-mode pin and SGND.
Standard 1% resistor values are used, and only every fourth E96
resistor value is used so the device can reliably recognize the
value of resistance connected to the pin while eliminating the
error associated with the resistor accuracy. Up to 31 unique
selections are available using a single resistor.
I2C/SMBUS METHOD
ZL2103 functions can be configured via the I2C/SMBus interface
using standard PMBus commands. Additionally, any value that
has been configured using the pin-strap or resistor setting
methods can also be re-configured and/or verified via the
I2C/SMBus. See Application Note AN2033 for more details.
The SMBus device address and VOUT_MAX are the only
parameters that must be set by external pins. All other device
parameters can be set via the I2C/SMBus. The device address is
set using the SA pin. VOUT_MAX is determined as 10% greater
than the voltage set by the VSET pin.
Resistor pin-straps are recommended to be used for all available
device parameters to allow a safe initial power-up before
configuration is stored via the I2C/SMBus. For example, this can
be accomplished by pin-strapping the undervoltage lockout
threshold (using SS pin) to a value greater than the expected
input voltage, thus preventing the device from enabling prior to
loading a configuration file.
FN6966.5
May 3, 2011
ZL2103
Power Conversion Functional
Description
Note: The internal bias regulators, VR and VRA, are not designed
to be outputs for powering other circuitry. Do not attach external
loads to any of these pins. Only the multi-mode pins may be
connected to the V2P5 pin for logic HIGH settings.
Internal Bias Regulators and Input Supply
Connections
High-side Driver Boost Circuit
The ZL2103 employs three internal low dropout (LDO) regulators
to supply bias voltages for internal circuitry, allowing it to operate
from a single input supply. The internal bias regulators are as
follows:
• VR: The VR LDO provides a regulated 7V bias supply for the
high-side MOSFET driver circuit. It is powered from the VDDS
pin and supplies bias current internally. A 4.7µF filter capacitor
is required at the VR pin. The VDDS pin directly supplies the
low-side MOSFET driver circuit.
• VRA: The VRA LDO provides a regulated 5V bias supply for the
current sense circuit and other analog circuitry. It is powered
from the VDDS pin and supplies bias current internally. A
4.7µF filter capacitor is required at the VRA pin.
VIN
VIN
VIN
VDDS
VDDS
VDDS
VR
VR
VR
VRA
VRA
VRA
The gate drive voltage for the high-side MOSFET driver is
generated by a floating bootstrap capacitor, CB (see Figure 9).
When the lower MOSFET (QL) is turned on, the SW node is pulled
to ground and the capacitor is charged from the internal VR bias
regulator through diode DB. When QL turns off and the upper
MOSFET (QH) turns on, the SW node is pulled up to VDDP and the
voltage on the bootstrap capacitor is boosted approximately 6.5V
above VDDP to provide the necessary voltage to power the highside driver. An internal Schottky diode is used with CB to help
maximize the high-side drive supply voltage.
Output Voltage Selection
The output voltage may be set to any voltage between 0.6V and
5.0V provided that the input voltage is higher than the desired
output voltage by an amount sufficient to prevent the device
from exceeding its maximum duty cycle specification. Using the
pin-strap method, VOUT can be set to one of three standard
voltages as shown in Table 2.
TABLE 2. PIN-STRAP OUTPUT VOLTAGE SETTINGS
4.5V ≤ VIN ≤ 5.5V
5.5V < V IN ≤ 7.5V
7.5V < V IN ≤ 14V
FIGURE 13. INPUT SUPPLY CONNECTIONS
• V2P5:The V2P5 LDO provides a regulated 2.5V bias supply for
the main controller circuitry. It is powered from the VRA LDO
and supplies bias current internally. A 10µF filter capacitor is
required at the V2P5 pin.
VSET
VOUT
LOW
1.2V
OPEN
1.5V
HIGH
3.3V
When the input supply (VDDS) is higher than 7.5V, the VR and
VRA pins should not be connected to any other pins. These pins
should only have a filter capacitor attached. Due to the dropout
voltage associated with the VR and VRA bias regulators, the
VDDS pin must be connected to these pins for designs operating
from a supply below 7.5V. Figure 13 illustrates the required
connections for all cases.
TABLE 3. ZL2103 START-UP SEQUENCE
STEP #
STEP NAME
1
Power Applied
Input voltage is applied to the ZL2103’s VDD pins (VDDP and VDDS).
Depends on input supply ramp
time
2
Internal Memory Check
The device will check for values stored in its internal memory. This step
is also performed after a Restore command.
3
Multi-mode Pin Check
Approx 5ms to 10ms (device will
ignore an enable signal or PMBus
traffic during this period)
4
Device Ready
5
Pre-ramp Delay
13
DESCRIPTION
The device loads values configured by the multi-mode pins.
The device is ready to accept an enable signal.
The device requires approximately 2ms following an enable signal and
prior to ramping its output. Additional pre-ramp delay may be
configured using the SS pin.
TIME DURATION
Approximately 2ms
FN6966.5
May 3, 2011
ZL2103
TABLE 4. RESISTORS FOR SETTING OUTPUT VOLTAGE
RSET
(k)
VOUT
(V)
10
0.6
11
0.7
12.1
0.75
13.3
0.8
14.7
0.9
16.2
1.0
17.8
1.1
19.6
1.2
21.5
1.25
23.7
1.3
26.1
1.4
28.7
1.5
31.6
1.6
34.8
1.7
38.3
1.8
42.2
1.9
46.4
2.0
51.1
2.1
56.2
2.2
61.9
2.3
68.1
2.4
75
2.5
82.5
2.6
90.9
2.7
100
2.8
110
2.9
121
3.0
133
3.1
147
3.2
162
3.3
178
5.0
The resistor setting method can be used to set the output voltage
to levels not available in Table 2. To set VOUT using resistors, use
Table 4 to select the resistor that corresponds to the desired
voltage.
The output voltage may also be set to any value between 0.6V
and 5.0V using the I2C interface. See Application Note AN2033
for details.
Start-up Procedure
The ZL2103 follows a specific internal start-up procedure after
power is applied to the VDD pins (VDDP and VDDS). Table 3
describes the start-up sequence.
14
If the device is to be synchronized to an external clock source, the
clock frequency must be stable prior to asserting the EN pin. The
device requires approximately 5ms to 10ms to check for specific
values stored in its internal memory. If the user has stored values
in memory, those values will be loaded. The device will then
check the status of all multi-mode pins and load the values
associated with the pin settings.
Once this process is completed, the device is ready to accept
commands via the I2C/SMBus interface and the device is ready
to be enabled. Once enabled, the device requires approximately
2ms before its output voltage may be allowed to start its
ramp-up process. If a soft-start delay period less than 2ms has
been configured (using PMBus commands), the device will
default to a 2ms delay period. If a delay period greater than 2ms
is configured, the device will wait for the configured delay period
prior to starting to ramp its output.
After the delay period has expired, the output will begin to ramp
towards its target voltage according to the pre-configured
soft-start ramp time that has been set using the SS pin. It should
be noted that if the EN pin is tied to VDDP or VDDS, the device
will still require approximately 5ms to 10ms before the output
can begin its ramp-up as described in Table 3.
Soft-start Delay and Ramp Times
It may be necessary to set a delay from when an enable signal is
received until the output voltage starts to ramp to its target
value. In addition, the designer may wish to set the time required
for VOUT to ramp to its target value after the delay period has
expired. These features may be used as part of an overall inrush
current management strategy or to control how fast a load IC is
turned on. The ZL2103 gives the system designer several options
for precisely and independently controlling both the delay and
ramp time periods.
The soft-start delay period begins when the EN pin is asserted
and ends when the delay time expires. The soft-start delay period
is set using the SS pin. Precise ramp delay timing mode reduces
the delay time variations and is available when the appropriate
bit in the MISC_CONFIG register had been set. Please refer to
Application Note AN2033 for details.
The soft-start ramp timer enables a precisely controlled ramp to
the nominal VOUT value that begins once the delay period has
expired. The ramp-up is guaranteed monotonic and its slope may
be precisely set using the SS pin. Using the pin-strap method, the
soft-start delay and ramp times can be set to one of three
standard values according to Table 5.
TABLE 5. SOFT-START DELAY AND RAMP SETTINGS
SS PIN SETTING
DELAY AND
RAMP TIME
(ms)
LOW
2
OPEN
5
HIGH
10
UVLO
7.5V
If the desired soft-start delay and ramp times are not one of the
values listed in Table 5, the times can be set to a custom value by
connecting a resistor from the SS pin to SGND using the
FN6966.5
May 3, 2011
ZL2103
appropriate resistor value from Table 6. The value of this resistor
is measured upon start-up or Restore and will not change if the
resistor is varied after power has been applied to the ZL2103
(see Figure 14).
SS
ZL
RSS
FIGURE 14. SS PIN RESISTOR CONNECTIONS
The soft-start delay and ramp times can also be set to custom
values via the I2C/SMBus interface. When the SS delay time is
set to 0ms, the device will begin its ramp-up after the internal
circuitry has initialized (~2ms). When the soft-start ramp period
is set to 0ms, the output will ramp up as quickly as the output
load capacitance and loop settings will allow. It is generally
recommended to set the soft-start ramp to a value greater than
500µs to prevent inadvertent fault conditions due to excessive
inrush current.
15
TABLE 6. DELAY AND RAMP CONFIGURATION
RSS
(k)
DELAY
TIME
(ms)
10
5
11
10
12.1
20
13.3
5
14.7
10
16.2
20
17.8
5
19.6
10
21.5
20
23.7
5
26.1
10
28.7
20
31.6
5
34.8
10
38.3
20
42.2
5
46.4
10
51.1
20
56.2
5
61.9
10
68.1
20
75
5
82.5
10
90.9
20
100
5
110
10
121
20
133
5
147
10
162
20
RAMP
TIME
(ms)
UVLO
(V)
5
4.5
10
2
5
5.5
10
20
2
5
7.5
10
20
FN6966.5
May 3, 2011
ZL2103
Power-good (PG)
TABLE 7. SYNC PIN FUNCTION SELECTION
The ZL2103 provides a Power-good (PG) signal that indicates the
output voltage is within a specified tolerance of its target level
and no fault condition exists. By default, the PG pin will assert if
the output is within +15%/-10% of the target voltage. These
limits may be changed via the I2C/SMBus interface. See
Application Note AN2033 for details.
CFG PIN
SYNC PIN FUNCTION
LOW
SYNC is configured as an input
OPEN
Auto detect mode
HIGH
SYNC is configured as an output fSW = 400kHz
A PG delay period is the time from when all conditions for
asserting PG are met and when the PG pin is actually asserted.
This feature is commonly used instead of an external reset
controller to signal the power supply is at its target voltage prior
to enabling any powered circuitry. By default, the ZL2103 PG
delay is set to 1ms and may be changed using the I2C/SMBus
interface as described in AN2033.
CONFIGURATION A: SYNC OUTPUT
Switching Frequency and PLL
CONFIGURATION B: SYNC INPUT
The ZL2103 incorporates an internal phase-locked loop (PLL) to
clock the internal circuitry. The PLL can be driven by an external
clock source connected to the SYNC pin. When using the internal
oscillator, the SYNC pin can be configured as a clock source for
other Zilker Labs devices.
When the SYNC pin is configured as an input (CFG pin is tied
LOW), the device will automatically check for an external clock
signal on the SYNC pin each time the EN pin is asserted. The
internal oscillator will then synchronize with the rising edge of the
external clock. The incoming clock signal must be in the range of
200kHz to 1MHz with a minimum duty cycle and must be stable
when the EN pin is asserted. The external clock signal must also
exhibit the necessary performance requirements (see the
“Electrical Specifications” table beginning on page 6).
The SYNC pin is a unique pin that can perform multiple functions
depending on how it is configured. The CFG pin is used to select
the operating mode of the SYNC pin as shown in Table 4.
Figure 15 illustrates the typical connections for each mode.
When the SYNC pin is configured as an output (CFG pin is tied
HIGH), the device will run from its internal oscillator and will drive
the resulting internal oscillator signal (preset to 400kHz) onto the
SYNC pin so other devices can be synchronized to it. The SYNC
pin will not be checked for an incoming clock signal while in this
mode.
SYNC
200kHz – 1MHz
ZL2103
A) SYNC = Output
ZL2103
B) SYNC = Input
Open
SYNC
OR
Logic
Low
N/C
ZL2103
SYNC
OR
RSYNC
CFG
N/C
Logic
High
CFG
SYNC
200kHz – 1MHz
ZL2103
CFG
N/C
CFG
SYNC
200kHz – 1MHz
CFG
Logic
High
ZL2103
C) SYNC = Auto Detect
FIGURE 15. SYNC PIN CONFIGURATIONS
16
FN6966.5
May 3, 2011
ZL2103
In the event of a loss of the external clock signal, the output
voltage may show transient over/undershoot. If this happens, the
ZL2103 will automatically switch to its internal oscillator and
switch at a frequency close to the previous incoming frequency.
CONFIGURATION C: SYNC AUTO DETECT
When the SYNC pin is configured in auto detect mode (CFG pin is
left OPEN), the device will automatically check for a clock signal
on the SYNC pin after enable is asserted. If a valid clock signal is
present, the ZL2103’s oscillator will then synchronize with the
rising edge of the external clock (refer to SYNC INPUT
description).
If no incoming clock signal is present, the ZL2103 will configure
the switching frequency according to the state of the SYNC pin as
listed in Table 8. In this mode, the ZL2103 will only read the
SYNC pin connection during the start-up sequence. Changes to
the SYNC pin connection will not affect fSW until the power
(VDDS) is cycled off and on again.
TABLE 8. SWITCHING FREQUENCY SELECTION
The switching frequency can also be set to any value between
200kHz and 1MHz using the I2C/SMBus interface. The available
frequencies are defined by
fSW = 8MHz/N, where whole number N is 8  N  40. See
Application Note AN2033 for details.
If a value other than fSW = 8MHz/N is entered using a PMBus
command, the internal circuitry will select the valid switching
frequency value that is closest to the entered value. For example,
if 810kHz is entered, the device will select 800kHz (N=10).
Note: The switching frequency read back using the appropriate
PMBus command will differ slightly from the selected value in
Table 9. The difference is due to hardware quantization.
When multiple Zilker Labs devices are used together, connecting
the SYNC pins together will force all devices to synchronize with
each other. The CFG pin of one device must set its SYNC pin as an
output and the remaining devices must have their SYNC pins set
as an input or as auto detect.
Note: Precise ramp timing mode must be disabled to use SYNC
clock auto detect.
SYNC PIN
FREQUENCY
LOW
200kHz
Component Selection
OPEN
400kHz
HIGH
1MHz
Resistor
See Table 9
The ZL2103 is a synchronous buck converter with integrated
MOSFETs that uses an external inductor and capacitors to
perform the power conversion process. The proper selection of
the external components is critical for optimized performance.
If the user wishes to run the ZL2103 at a frequency not listed in
Table 8, the switching frequency can be set using an external
resistor, RSYNC, connected between SYNC and SGND using
Table 9.
To select the appropriate external components for the desired
performance goals, the power supply requirements listed in
Table 10 must be defined.
TABLE 10. POWER SUPPLY REQUIREMENTS
TABLE 9. RSYNC RESISTOR VALUES
RSYNC
(k)
FSW
(kHz)
10
200
PARAMETER
RANGE
EXAMPLE
VALUE
Input voltage (VIN)
4.5V to
14.0V
12V
Output voltage (VOUT)
0.6V to
5.0V
3.3V
11
222
12.1
242
13.3
267
Output current (IOUT)
0A to 3A
2A
14.7
296
Output voltage ripple (Vorip)
320
< 3% of
VOUT
±1% of VOUT
16.2
17.8
364
Output load step (Iostep)
< Io
±25% of Io
19.6
400
Output load step rate
-
2.5A/µs
21.5
421
Output deviation due to load step
-
23.7
471
±3% of VOUT
26.1
533
+120°C
+85°C
28.7
571
Desired efficiency
-
85%
31.6
615
34.8
667
Other considerations
-
Optimize for small
size
38.3
727
Maximum PCB temp.
42.2
889
DESIGN GOAL TRADE-OFFS
46.4
1000
The design of the buck power stage requires several
compromises among size, efficiency and cost. The inductor core
loss increases with frequency, so there is a trade-off between a
17
FN6966.5
May 3, 2011
ZL2103
small output filter made possible by a higher switching frequency
and getting better power supply efficiency. Size can be decreased
by increasing the switching frequency at the expense of
efficiency. Cost can be minimized by using through-hole
inductors and capacitors; however these components are
physically large.
To start the design, select a frequency based on Table 11. This
frequency is a starting point and may be adjusted as the design
progresses.
TABLE 11. CIRCUIT DESIGN CONSIDERATIONS
FREQUENCY RANGE
EFFICIENCY
CIRCUIT SIZE
200kHz to 400kHz
Highest
Larger
400kHz to 800kHz
Moderate
Smaller
800kHz to 1MHz
Lower
Smallest
INDUCTOR SELECTION
The output inductor selection process must include several
trade-offs. A high inductance value will result in a low ripple
current (Iopp), which will reduce output capacitance and produce
a low output ripple voltage, but may also compromise output
transient load performance. Therefore, a balance must be struck
between output ripple and optimal load transient performance. A
good starting point is to select the output inductor ripple equal to
the expected load transient step magnitude (Iostep):
I opp  I ostep
(EQ. 2)
Now the output inductance can be calculated using Equation 3,
where VINM is the maximum input voltage:
LOUT
 V
VOUT  1  OUT
 V INM

fsw  I opp



I opp
(EQ. 4)
Select an inductor rated for the average DC current with a peak
current rating above the peak current computed in Equation 4.
In overcurrent or short-circuit conditions, the inductor may have
currents greater than 2X the normal maximum rated output
current. It is desirable to use an inductor that still provides some
inductance to protect the load and the internal MOSFETs from
damaging currents in this situation.
Once an inductor is selected, the DCR and core losses in the
inductor are calculated. Use the DCR specified in the inductor
manufacturer’s data sheet.
PLDCR  DCR  I Lrms
2
2
I Lrms  I OUT 
(EQ. 5)
(EQ. 6)
opp
12
where IOUT is the maximum output current. Next, calculate the
core loss of the selected inductor. Since this calculation is
specific to each inductor and manufacturer, refer to the chosen
inductor data sheet. Add the core loss and the DCR loss and
compare the total loss to the maximum power dissipation
recommendation in the inductor data sheet.
OUTPUT CAPACITOR SELECTION
Several trade-offs must also be considered when selecting an
output capacitor. Low ESR values are needed to have a small
output deviation during transient load steps (Vosag) and low
output voltage ripple (Vorip). However, capacitors with low ESR,
such as semi-stable (X5R and X7R) dielectric ceramic capacitors,
also have relatively low capacitance values. Many designs can
use a combination of high capacitance devices and low ESR
devices in parallel.
For high ripple currents, a low capacitance value can cause a
significant amount of output voltage ripple. Likewise, in high
transient load steps, a relatively large amount of capacitance is
needed to minimize the output voltage deviation while the
inductor current ramps up or down to the new steady state
output current value.
As a starting point, apportion one-half of the output ripple
voltage to the capacitor ESR and the other half to capacitance, as
shown in Equations 7 and 8:
I opp
8  f sw 
(EQ. 3)
2
I 
2
C OUT 
The average inductor current is equal to the maximum output
current. The peak inductor current (ILpk) is calculated using
Equation 4 where IOUT is the maximum output current:
I Lpk  I OUT 
ILrms is given by Equation 6:
ESR 
(EQ. 7)
Vorip
2
Vorip
(EQ. 8)
2  I opp
Use these values to make an initial capacitor selection, using a
single capacitor or several capacitors in parallel.
After a capacitor has been selected, the resulting output voltage
ripple can be calculated using Equation 9:
Vorip  I opp  ESR 
I opp
8  f sw  C OUT
Because each part of this equation was made to be less than or
equal to half of the allowed output ripple voltage, the Vorip should
be less than the desired maximum output ripple.
INPUT CAPACITOR
It is highly recommended that dedicated input capacitors be
used in any point-of-load design, even when the supply is
powered from a heavily filtered 5V or 12V “bulk” supply from an
off-line power supply. This is because of the high RMS ripple
current that is drawn by the buck converter topology. This ripple
(ICINrms) can be determined from Equation 10:
I CINrms  I OUT  D  (1  D)
18
(EQ. 9)
(EQ. 10)
FN6966.5
May 3, 2011
ZL2103
Without capacitive filtering near the power supply circuit, this
current would flow through the supply bus and return planes,
coupling noise into other system circuitry. The input capacitors
should be rated at 1.2X the ripple current calculated in Equation
10 to avoid overheating of the capacitors due to the high ripple
current, which can cause premature failure. Ceramic capacitors
with X7R or X5R dielectric with low ESR and 1.1X the maximum
expected input voltage are recommended.
BOOTSTRAP CAPACITOR SELECTION
The high-side driver boost circuit utilizes an internal Schottky
diode (DB) and an external bootstrap capacitor (CB) to supply
sufficient gate drive for the high-side MOSFET driver. CB should
be a 47nF ceramic type rated for at least 10V.
CV2P5 SELECTION
This capacitor is used to both stabilize and provide noise filtering
for the 2.5V internal power supply. It should be between 4.7µF
and 10µF, should use a semi-stable X5R or X7R dielectric
ceramic with a low ESR (less than 10m) and should have a
rating of 4V or more.
CVR SELECTION
This capacitor is used to both stabilize and provide noise filtering
for the 7V reference supply. It should be between 4.7µF and
10µF, should use a semi-stable X5R or X7R dielectric ceramic
capacitor with a low ESR (less than 10m) and should have a
rating of 10V or more. Because the current for the bootstrap
supply is drawn from this capacitor, CVR should be sized at least
10X the value of CB so that a discharged CB does not cause the
voltage on it to droop excessively during a CB recharge pulse.
CVRA SELECTION
This capacitor is used to both stabilize and provide noise filtering
for the analog 5V reference supply. It should be between 2.2µF
and 10µF, should use a semi-stable X5R or X7R dielectric
ceramic capacitor with a low ESR (less than 10m) and should
have a rating of 6.3V or more.
THERMAL CONSIDERATIONS
In typical applications, the ZL2103’s high efficiency will limit the
internal power dissipation inside the package. However, in
applications that require a high ambient operating temperature
the user must perform some thermal analysis to ensure that the
ZL2103’s maximum junction temperature is not exceeded.
The ZL2103 has a maximum junction temperature limit of
+125°C, and the internal over-temperature limiting circuitry will
force the device to shut down if its junction temperature exceeds
this threshold. In order to calculate the maximum junction
temperature, the user must first calculate the power dissipated
inside the IC (PQ) as expressed in Equation 11:

2
PQ  I LOAD
R
DS ON QH
D  R
DS ON QL
1 D
The design should include a current limiting mechanism to
protect the power supply from damage and prevent excessive
current from being drawn from the input supply in the event that
the output is shorted to ground or an overload condition is
imposed on the output. Current limiting is accomplished by
sensing the current through the circuit during a portion of the
duty cycle. The current limit threshold is set to 4.5A by default.
The current limit threshold can set to a custom value via the
I2C/SMBus interface. Please refer to Application Note AN2033
for further details.
Additionally, the ZL2103 gives the power supply designer several
choices for the fault response during over or under current
conditions. The user can select the number of violations allowed
before declaring a fault, a blanking time and the action taken when
a fault is detected. The blanking time represents the time when no
current measurement is taken. This is to avoid taking a reading just
after a current load step (less accurate due to potential ringing).
Please refer to Application note AN2033 for further details.
Loop Compensation
The ZL2103 operates as a voltage-mode synchronous buck
controller with a fixed frequency PWM scheme. Although the
ZL2103 uses a digital control loop, it operates much like a
traditional analog PWM controller. Figure 16 is a simplified block
diagram of the ZL2103 control loop, which differs from an analog
control loop only by the constants in the PWM and compensation
blocks. As in the analog controller case, the compensation block
compares the output voltage to the desired voltage reference and
compensation zeroes are added to keep the loop stable. The
resulting integrated error signal is used to drive the PWM logic,
converting the error signal to a duty cycle to drive the internal
MOSFETs.
VIN
D
L
VOUT
DPWM
1-D
C
RO
RC
Compensation
(EQ. 12)
Where TPCB is the expected maximum printed circuit board
temperature and JC is the junction-to-case thermal resistance
for the ZL2103 package.
19
The ZL2103 incorporates a patented “lossless” current sensing
method across the internal low-side MOSFET that is independent
of rDS(ON) variations, including temperature. The default value for
the gain, which does not represent a rDS(ON) value, and the offset
of the internal current sensing circuit can be modified by the
IOUT_CAL_GAIN and IOUT_CAL_OFFSET commands.
(EQ. 11)
The maximum operating junction temperature can then be
calculated using Equation 12:
T j max  TPCB  PQ  θ JC 
Current Sensing and Current Limit Threshold
Selection
FIGURE 16. CONTROL LOOP BLOCK DIAGRAM
FN6966.5
May 3, 2011
ZL2103
TABLE 12. RESISTOR SETTING FOR LOOP COMPENSATION
the conducting state at the same time. This is because
potentially damaging currents flow in the circuit if both MOSFETs
are on simultaneously for periods of time exceeding a few
nanoseconds. Conversely, long periods of time in which both
MOSFETs are off reduces overall circuit efficiency by allowing
current to flow in their parasitic body diodes.
G(dB)
Q
fsw/fn
FC
(k)
24
0.150
115.000
Open or 11
27
0.150
115.000
Low or 10
27
0.150
69.147
13.3
27
0.150
41.577
14.7
27
0.300
115.000
16.2
27
0.300
69.147
17.8
27
0.300
41.577
19.6
27
0.300
25.000
21.5
27
0.600
69.147
23.7
27
0.600
41.577
26.1
27
0.600
25.000
28.7
30
0.150
115.000
High or 12.1
30
0.150
69.147
31.6
30
0.150
41.577
34.8
30
0.300
115.000
38.3
30
0.300
69.147
42.2
30
0.300
41.577
46.4
30
0.300
25.000
51.1
30
0.600
69.147
56.2
1. Continue operating without interruption.
30
0.600
41.577
61.9
30
0.600
25.000
68.1
33
0.150
115.000
75.0
2. Continue operating for a given delay period, followed by
shutdown if the fault still exists. The device will remain in
shutdown until instructed to restart.
33
0.150
69.147
82.5
33
0.150
41.577
90.9
33
0.300
115.000
100.0
33
0.300
69.147
110.0
33
0.300
41.577
121.0
33
0.300
25.000
133.0
33
0.600
69.147
147.0
Output Overvoltage Protection
33
0.600
41.577
162.0
33
0.600
25.000
178.0
The ZL2103 offers an internal output overvoltage protection
circuit that can be used to protect sensitive load circuitry from
being subjected to a voltage higher than its prescribed limits. A
hardware comparator is used to compare the actual output
voltage (seen at the VSEN pin) to a threshold set to 15% higher
than the target output voltage (the default setting). If the VSEN
voltage exceeds this threshold, the PG pin will de-assert and the
device can then respond in a number of ways as follows:
In the ZL2103, the compensation zeros are set by configuring the
FC pin or via the I2C/SMBus interface once the user has
calculated the required settings. This method eliminates the
inaccuracies due to the component tolerances associated with
using external resistors and capacitors required with traditional
analog controllers.
The loop compensation coefficients can also be set via the
I2C/SMBus interface. Please refer to Application Note AN2033
for further details. Also refer to Application Note AN2035 for
further technical details on setting loop compensation.
Driver Dead-time Control
The ZL2103 utilizes a predetermined fixed dead-time applied
between the gate drive signals for the top and bottom MOSFETs.
In a synchronous buck converter, the MOSFET drive circuitry must
be operated such that the top and bottom MOSFETs are never in
20
Therefore, it is advantageous to minimize the dead-time to
provide peak optimal efficiency without compromising system
reliability. The ZL2103 has optimized the dead-time for the
integrated MOSFETs to maximizing efficiency.
Power Management Functional
Description
Input Undervoltage Lockout
The input undervoltage lockout (UVLO) prevents the ZL2103 from
operating when the input falls below a preset threshold,
indicating the input supply is out of its specified range. The UVLO
threshold (VUVLO) can be set to either 4.5V or 10.8V using the SS
pin according to Table 6.
The UVLO voltage can also be set to any value between 2.85V
and 16V via the I2C/SMBus interface.
Once an input undervoltage fault condition occurs, the device
can respond in a number of ways as follows:
3. Initiate an immediate shutdown until the fault has been
cleared. The user can select a specific number of retry
attempts.
The default response from a UVLO fault is an immediate shutdown
of the device. Please refer to Application Note AN2033 for details on
how to configure the UVLO threshold or to select specific UVLO fault
response options via the I2C/SMBus interface.
1. Initiate an immediate shutdown until the fault has been
cleared. The user can select a specific number of retry
attempts.
2. Turn off the high-side MOSFET and turn on the low-side
MOSFET. The low-side MOSFET remains on until the device
attempts a restart.
The default response from an overvoltage fault is to immediately
shut down. For continuous overvoltage protection when operating
from an external clock, the only allowed response is an
immediate shutdown. Please refer to Application Note AN2033
FN6966.5
May 3, 2011
ZL2103
for details on how to select specific overvoltage fault response
options via I2C/SMBus.
Output Pre-Bias Protection
An output pre-bias condition exists when an externally applied
voltage is present on a power supply’s output before the power
supply’s control IC is enabled. Certain applications require that
the converter not be allowed to sink current during start up if a
pre-bias condition exists at the output. The ZL2103 provides prebias protection by sampling the output voltage prior to initiating
an output ramp.
If a pre-bias voltage lower than the target voltage exists after the
pre-configured delay period has expired, the target voltage is set
to match the existing pre-bias voltage and both drivers are
enabled. The output voltage is then ramped to the final
regulation value at the ramp rate set by the SS pin.
The actual time the output will take to ramp from the pre-bias
voltage to the target voltage will vary depending on the pre-bias
voltage but the total time elapsed from when the delay period
expires and when the output reaches its target value will match
the pre-configured ramp time (see Figure 17).
If a pre-bias voltage higher than the target voltage exists after the
pre-configured delay period has expired, the target voltage is set
to match the existing pre-bias voltage and both drivers are
enabled with a PWM duty cycle that would ideally create the prebias voltage.
Once the pre-configured soft-start ramp period has expired, the
PG pin will be asserted (assuming the pre-bias voltage is not
higher than the overvoltage limit). The PWM will then adjust its
duty cycle to match the original target voltage and the output will
ramp down to the pre-configured output voltage.
If a pre-bias voltage higher than the overvoltage limit exists, the
device will not initiate a turn-on sequence and will declare an
overvoltage fault condition to exist. In this case, the device will
respond based on the output overvoltage fault response method
that has been selected. See “Output Overvoltage Protection” on
page 20 for response options due to an overvoltage condition.
21
FIGURE 17. OUTPUT RESPONSES TO PRE-BIAS VOLTAGES
FN6966.5
May 3, 2011
ZL2103
Output Overcurrent Protection
Voltage Tracking
The ZL2103 can protect the power supply from damage if the
output is shorted to ground or if an overload condition is imposed
on the output. Once the current limit threshold has been selected
(see “Current Sensing and Current Limit Threshold Selection” on
page 19), the user may determine the desired course of action in
response to the fault condition. The following overcurrent
protection response options are available:
Numerous high performance systems place stringent demands
on the order in which the power supply voltages are turned on.
This is particularly true when powering FPGAs, ASICs, and other
advanced processor devices that require multiple supply voltages
to power a single die. In most cases, the I/O interface operates at
a higher voltage than the core and therefore the core supply
voltage must not exceed the I/O supply voltage according to the
manufacturers' specifications.
2. Initiate a shutdown and attempt to restart a preset number of
times with a preset delay period between attempts.
3. Continue operating for a given delay period, followed by
shutdown if the fault still exists.
4. Continue operating through the fault (this could result in
permanent damage to the power supply).
5. Initiate an immediate shutdown.
6. The default response from an overcurrent fault is an
immediate shutdown of the device. Please refer to
Application Note AN2033 for details on how to select specific
overcurrent fault response options via I2C/SMBus.
Thermal Overload Protection
The ZL2103 includes an on-chip thermal sensor that
continuously measures the internal temperature of the die and
will shutdown the device when the temperature exceeds the
preset limit. The factory default temperature limit is set to
+125°C, but the user may set the limit to a different value if
desired. See Application Note AN2033 for details. Note that
setting a higher thermal limit via the I2C/SMBus interface may
result in permanent damage to the device. Once the device has
been disabled due to an internal temperature fault, the user may
select one of several fault response options as follows:
1. Initiate a shutdown and attempt to restart an infinite number
of times with a preset delay period between attempts.
Voltage tracking protects these sensitive ICs by limiting the
differential voltage between multiple power supplies during the
power-up and power down sequence. The ZL2103 integrates a
lossless tracking scheme that allows its output to track a voltage
that is applied to the VTRK pin with no additional components
required. The VTRK pin is an analog input that, when tracking
mode is enabled, configures the voltage applied to the VTRK pin
to act as a reference for the device’s output regulation.
The ZL2103 offers two modes of tracking. Figure 18 illustrates
the output voltage waveform for the two tracking modes.
1. Coincident. This mode configures the ZL2103 to ramp its
output voltage at the same rate as the voltage applied to the
VTRK pin.
2. Ratiometric. This mode configures the ZL2103 to ramp its
output voltage at a rate that is a percentage of the voltage
applied to the VTRK pin. The default setting is 50%, but an
external resistor may be used to configure a different tracking
ratio.
V IN
ZL
SW
VTRK
1. Initiate a shutdown and attempt to restart an infinite number
of times with a preset delay period between attempts.
VOUT
VTRK
V OUT
2. Initiate a shutdown and attempt to restart a preset number of
times with a preset delay period between attempts.
VTRK
3. Continue operating for a given delay period, followed by
shutdown if the fault still exists.
VOUT
4. Continue operating through the fault (this could result in
permanent damage to the power supply).
5. Initiate an immediate shutdown.
If the user has configured the device to restart, the device will
wait the preset delay period (if configured to do so) and will then
check the device temperature. If the temperature has dropped
below a threshold that is approximately +15°C lower than the
selected temperature fault limit, the device will attempt to restart. If the temperature still exceeds the fault limit the device
will wait the preset delay period and retry again.
The default response from a temperature fault is an immediate
shutdown of the device. Please refer to Application Note AN2033
for details on how to select specific temperature fault response
options via I2C/SMBus.
22
Time
Coincident
V OUT
VTRK
VOUT
Time
Ratiometric
FIGURE 18. TRACKING MODES
The master device in a tracking group is defined as the device
that has the highest target output voltage within the group. This
master device will control the ramp rate of all tracking devices
and is not configured for tracking mode. A delay of at least 10ms
must be configured into the master device using the SS pin, and
FN6966.5
May 3, 2011
ZL2103
the user may also configure a specific ramp rate using the SS
pin. Tracking mode is enabled through the CFG pin, as shown in
Table 16, and configured through the SS pin, as shown in
Table 13.
Any device that is configured for tracking mode will ignore its
soft-start delay and ramp time settings (SS pin) and its output
will take on the turn-on/turn-off characteristics of the reference
voltage present at the VTRK pin. All of the ENABLE pins in the
tracking group must be connected together and driven by a
single logic source.
Tracking mode can also be configured via the I2C/SMBus
interface by using the TRACK_CONFIG PMBus command. Please
refer to Application Note AN2033 for more information on
configuring tracking mode using PMBus.
Voltage Margining
The ZL2103’s output will be forced higher than its nominal set
point when the MGN command is set HIGH, and the output will
be forced lower than its nominal set point when the MGN
command is set LOW. Default margin limits of VNOM ±5% are preloaded in the factory, but the margin limits can be modified
through the I2C/SMBus interface to as high as VNOM + 10% or as
low as 0V, where VNOM is the nominal output voltage set point
determined by the VSET pin. A safety feature prevents the user
from configuring the output voltage to exceed VNOM + 10% under
any conditions.
The margin limits and the MGN command can both be set
individually through the I2C/SMBus interface. Additionally, the
transition rate between the nominal output voltage and either
margin limit can be configured through the I2C/SMBus interface.
Please refer to Application Note AN2033 for detailed instructions
on modifying the margining configurations.
The ZL2103 offers a simple means to vary its output higher or
lower than its nominal voltage setting in order to determine
whether the load device is capable of operating over its specified
supply voltage range. The MGN command is set by driving the
MGN pin or through the I2C/SMBus interface. The MGN pin is a
tri-level input that is continuously monitored and can be driven
directly by a processor I/O pin or other logic-level output.
TABLE 13. TRACKING MODE CONFIGURATION
RSS
(k)
UVLO
(V)
TRACKING RATIO
(%)
19.6
Limited by target voltage
21.5
100
23.7
26.1
28.7
UPPER TRACK LIMIT
Output will always follow VTRK
Limited by VTRK pin voltage
Limited by target voltage
50
34.8
Output not allowed to decrease before PG
Output not allowed to decrease before PG
Output will always follow VTRK
Limited by VTRK pin voltage
38.3
Output not allowed to decrease before PG
Output will always follow VTRK
56.2
Limited by target voltage
61.9
100
68.1
82.5
Output not allowed to decrease before PG
Output will always follow VTRK
5.5
31.6
75
RAMP-UP/DOWN BEHAVIOR
Output not allowed to decrease before PG
Output will always follow VTRK
Limited by VTRK pin voltage
Output not allowed to decrease before PG
Output will always follow VTRK
7.5
Limited by target voltage
90.9
50
100
110
Output not allowed to decrease before PG
Output will always follow VTRK
Limited by VTRK pin voltage
Output not allowed to decrease before PG
Output will always follow VTRK
23
FN6966.5
May 3, 2011
ZL2103
I2C/SMBus Communications
The ZL2103 provides an I2C/SMBus digital interface that enables
the user to configure all aspects of the device operation as well
as monitor the input and output parameters. The ZL2103 can be
used with any standard 2-wire I2C host device.
In addition, the device is compatible with SMBus version 2.0 and
includes an SALRT line to help mitigate bandwidth limitations
related to continuous fault monitoring. Pull-up resistors are
required on the I2C/SMBus as specified in the SMBus 2.0
specification. The ZL2103 accepts most standard PMBus
commands. When controlling the device with PMBus commands,
it is recommended that the enable pin is tied to SGND.
The minimum pull-up resistance should be limited to a value that
enables any device to assert the bus to a voltage that will ensure
a logic 0 (typically 0.8V at the device monitoring point) given the
pull-up voltage (5V if tied to VRA) and the pull-down current
capability of the ZL2103 (nominally 4mA).
TABLE 15. SMBus ADDRESS VALUES
RSA
(k)
SMBus Address
10
0x20
11
0x21
12.1
0x22
I2C/SMBus Device Address Selection
13.3
0x23
When communicating with multiple devices using the
I2C/SMBus interface, each device must have its own unique
address so the host can distinguish between the devices. The
device address can be set according to the pin-strap options
listed in Table 14. Address values are right-justified.
14.7
0x24
16.2
0x25
17.8
0x26
19.6
0x27
21.5
0x28
TABLE 14. SMBus DEVICE ADDRESS SELECTION
SA PIN SETTING
SMBus ADDRESS
23.7
0x29
LOW
0x20
26.1
0x2A
OPEN
0x21
28.7
0x2B
HIGH
0x22
31.6
0x2C
34.8
0x2D
38.3
0x2E
42.2
0x2F
Digital-DC Bus
46.4
0x30
The Digital-DC Communications (DDC) bus is used to
communicate between Zilker Labs Digital-DC devices. This
dedicated bus provides the communication channel between
devices for features such as sequencing and fault spreading. The
DDC pin on all Digital-DC devices in an application should be
connected together. A pull-up resistor is required on the DDC bus
in order to guarantee the rise time as expressed in Equation 13:
51.1
0x31
56.2
0x32
61.9
0x33
68.1
0x34
75
0x35
82.5
0x36
90.9
0x37
100
0x38
110
0x39
121
0x3A
133
0x3B
147
0x3C
162
0x3D
If additional device addresses are required, a resistor can be
connected to the SA pin according to Table 15 to provide up to 30
unique device addresses.
Rise time = R PU  C LOAD  1  s
(EQ. 13)
Where RPU is the DDC bus pull-up resistance and CLOAD is the bus
loading. The pull-up resistor may be tied to VRA or to an external
3.3V or 5V supply as long as this voltage is present prior to or
during device power-up. As rules of thumb, each device
connected to the DDC bus presents approximately 10pF of
capacitive loading, and each inch of FR4 PCB trace introduces
approximately 2pF. The ideal design will use a central pull-up
resistor that is well matched to the total load capacitance. In
power module applications, the user should consider whether to
place the pull-up resistor on the module or on the PCB of the end
application.
24
FN6966.5
May 3, 2011
ZL2103
Phase Spreading
When multiple point of load converters share a common DC
input supply, it is desirable to adjust the clock phase offset of
each device such that not all devices start to switch
simultaneously. Setting each converter to start its switching cycle
at a different point in time can dramatically reduce input
capacitance requirements and efficiency losses. Since the peak
current drawn from the input supply is effectively spread out over
a period of time, the peak current drawn at any given moment is
reduced and the power losses proportional to the IRMS2 are
reduced dramatically.
TABLE 16. CFG PIN CONFIGURATIONS FOR SEQUENCING AND
TRACKING
RCFG
SYNC PIN
CONFIGURATION
Low
Input
Open
Auto detect
High
Output
10k
Input
11k
Auto detect
In order to enable phase spreading, all converters must be
synchronized to the same switching clock. The CFG pin is used to
set the configuration of the SYNC pin for each device as
described in “Switching Frequency and PLL” on page 16.
12.1k
Output
14.7k
Input
16.2k
Auto detect
Selecting the phase offset for the device is accomplished by
selecting a device address according to the following equation:
17.8k
Output
21.5k
Input
Phase offset = device address x 45°
23.7k
Auto detect
For example:
26.1k
Output
• A device address of 0x00 or 0x20 would configure no phase
offset
31.6k
Input
34.8k
Auto detect
38.3k
Output
46.4k
Input
51.1k
Auto detect
56.2k
Output
• A device address of 0x01 or 0x21 would configure 45° of
phase offset
• A device address of 0x02 or 0x22 would configure 90° of
phase offset
The phase offset of each device may also be set to any value
between 0° and 360° in 22.5° increments via the I2C/SMBus
interface. Refer to Application Note AN2033 for further details.
Output Sequencing
A group of Zilker Labs devices may be configured to power up in
a predetermined sequence. This feature is especially useful when
powering advanced processors, FPGAs, and ASICs that require
one supply to reach its operating voltage prior to another supply
reaching its operating voltage in order to avoid latch-up from
occurring. Multi-device sequencing can be achieved by
configuring each device through the I2C/SMBus interface or by
using Zilker Labs patented autonomous sequencing mode.
Autonomous sequencing mode configures sequencing by using
events transmitted between devices over the DDC bus.
The sequencing order is determined using each device’s SMBus
address. Using autonomous sequencing mode (configured using
the CFG pin), the devices must be assigned sequential SMBus
addresses with no missing addresses in the chain. This mode will
also constrain each device to have a phase offset according to its
SMBus address as described in section “Phase Spreading” on
page 25.
25
SEQUENCING CONFIGURATION
Sequencing and Tracking are
disabled.
Sequencing and Tracking are
disabled.
Device is FIRST in nested
sequence. Tracking disabled.
Device is LAST in nested
sequence. Tracking disabled.
Device is MIDDLE in nested
sequence. Tracking disabled.
Sequence disabled. Tracking
enabled as defined in Table 13.
The sequencing group will turn on in order starting with the
device with the lowest SMBus address and will continue through
to turn on each device in the address chain until all devices
connected have been turned on. When turning off, the device
with the highest SMBus address will turn off first followed in
reverse order by the other devices in the group.
Sequencing is configured by connecting a resistor from the CFG
pin to ground as described in Table 16. The CFG pin is also used
to set the configuration of the SYNC pin as well as to determine
the sequencing method and order. Please refer to section
“Switching Frequency and PLL” on page 16 for more details on
the operating parameters of the SYNC pin.
Multiple device sequencing may also be achieved by issuing
PMBus commands to assign the preceding device in the
sequencing chain as well as the device that will follow in the
sequencing chain. This method places fewer restrictions on the
SMBus address (no need of sequential address) and also allows
the user to assign any phase offset to any device irrespective of
its SMBus device address.
The Enable pins of all devices in a sequencing group must be tied
together and driven high to initiate a sequenced turn-on of the
group. Enable must be driven low to initiate a sequenced turnoff
of the group. Please refer to Application Note AN2033 for details
on sequencing via the I2C/SMBus interface.
FN6966.5
May 3, 2011
ZL2103
Fault Spreading
Digital-DC devices can be configured to broadcast a fault event
over the DDC bus to the other devices in the group. When a nondestructive fault occurs and the device is configured to shut down
on a fault, the device will shut down and broadcast the fault
event over the DDC bus. The other devices on the DDC bus will
shut down together if configured to do so, and will attempt to restart in their prescribed order if configured to do so.
Monitoring via I2C/SMBus
A system controller can monitor a wide variety of different
ZL2103 system parameters through the I2C/SMBus interface.
The device can monitor for fault conditions by monitoring the
SALRT pin, which will be pulled low when any number of preconfigured fault conditions occur.
The device can also be monitored continuously for any number of
power conversion parameters including input voltage, output
voltage, output current, internal junction temperature, switching
frequency and duty cycle.
The PMBus host should respond to SALRT as follows:
1. ZL device pulls SALRT low.
2. PMBus host detects that SALRT is now low, performs
transmission with Alert Response Address to find which ZL
device is pulling SALRT low.
3. PMBus host talks to the ZL device that has pulled SALRT low.
The actions that the host performs are up to the system
designer.
If multiple devices are faulting, SALRT will still be low after doing
the above steps and will require transmission with the Alert
Response Address repeatedly until all faults are cleared. Please
refer to Application Note AN2033 for details on how to monitor
specific parameters via the I2C/SMBus interface.
Snapshot™ Parametric Capture
The ZL2103 offers a special feature that enables the user to
capture parametric data during normal operation or following a
fault. The Snapshot functionality is enabled by setting bit 1 of
MISC_CONFIG to 1.
See AN2033 for details on using Snapshot in addition to the
parameters supported. The Snapshot feature enables the user to
read the parameters via a block read transfer through the
SMBus. This can be done during normal operation, although it
should be noted that reading the 22 bytes will occupy the SMBus
for some time.
1400µs depending on whether the data is set up for a block
write. Undesirable results may be observed if the device’s VDD
supply drops below 3.0V during this process.
TABLE 17. SNAPSHOT_CONTROL COMMAND
DATA
VALUE
DESCRIPTION
1
Copies current SNAPSHOT values from Flash memory to
RAM for immediate access using SNAPSHOT command.
2
Writes current SNAPSHOT values to Flash memory. Only
available when device is disabled.
In the event that the device experiences a fault and power is lost,
the user can extract the last SNAPSHOT parameters stored
during the fault by writing a 1 to SNAPSHOT_CONTROL (transfers
data from Flash memory to RAM) and then issuing a SNAPSHOT
command (reads data from RAM via SMBus).
Non-Volatile Memory and Device Security
Features
The ZL2103 has internal non-volatile memory where user
configurations are stored. Integrated security measures ensure
that the user can only restore the device to a level that has been
made available to them. Refer to “Start-up Procedure” on
page 14 for details on how the device loads stored values from
internal memory during start-up.
During the initialization process, the ZL2103 checks for stored
values contained in its internal memory. The ZL2103 offers two
internal memory storage units that are accessible by the user as
follows:
1. Default Store: A power supply module manufacturer may
want to protect the module from damage by preventing the
user from being able to modify certain values that are related
to the physical construction of the module. In this case, the
module manufacturer would use the Default Store and would
allow the user to restore the device to its default setting but
would restrict the user from restoring the device to the factory
settings.
2. User Store: The manufacturer of a piece of equipment may
want to provide the ability to modify certain power supply
settings while still protecting the equipment from modifying
values that can lead to a system level fault. The equipment
manufacturer would use the User Store to achieve this goal.
Please refer to Application Note AN2033 for details on how to set
specific security measures via the I2C/SMBus interface.
The SNAPSHOT_CONTROL command enables the user to store
the snapshot parameters to Flash memory in response to a
pending fault as well as to read the stored data from Flash
memory after a fault has occurred. Table 17 describes the usage
of this command. Automatic writes to Flash memory following a
fault are triggered when any fault threshold level is exceeded,
provided that the specific fault’s response is to shut down
(writing to Flash memory is not allowed if the device is configured
to re-try following the specific fault condition).
It should also be noted that the device’s VDD voltage must be
maintained during the time when the device is writing the data to
Flash memory; a process that requires between 700µs to
26
FN6966.5
May 3, 2011
ZL2103
Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to web to make
sure you have the latest Rev.
DATE
REVISION
4/6/2011
FN6966.5
CHANGE
-Updated order info on page 4 as follows:
Ld finish note updated matching intrepid.
Replaced parts ZL2103ALAN with ZL2103ALAF.
Replaced Pkg DWG# L36.6x6A with L36.6x6C
-Abs Max Ratings on page 6, changed following from:
High-Side Sup Voltage for BST Pin. . -0.3V to 30V
to
High-Side Sup Voltage for BST Pin. . -0.3V to 25V
-Updated over-temp note in MIN MAX columns of spec table on page 8 from "Parameters with MIN and/or
MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by
characterization & are not production tested." to "Compliance to datasheet limits is assured by one or more
methods: production test, characterization and/or design."
-Removed "Limits established by characterization & are not production tested" note
-Replaced on page 28 POD L36.6x6A with L36.6x6C matching ordering info.
12/8/2010
FN6966.4
Added following statement to disclaimer on page 27: “This product is subject to a license from Power One, Inc.
related to digital power technology as set forth in U.S. Patent No. 7,000,125 and other related patents owned
by Power One, Inc. These license rights do not extend to stand-alone POL regulators unless a royalty is paid to
Power One, Inc.”
6/24/2010
FN6966.3
Corrected a typo in Table 15 on page 24. In the first column, swapped 34.8 and 31.6 so that 31.6 is for
address 0x2C and 34.8 is for address 0x2D.
2/11/2010
FN6966.2
Added “LatchupTested to JESD78” to “Absolute Maximum Ratings” on page 6.
01/22/2010
FN6966.1
Changed order information parts from “ZL2103ALAF, ZL2103ALAFT, ZL2103ALAFTK” TO “ZL2103ALAN,
ZL2103ALANT, ZL2103ALANTK”
12/15/2009
FN6966.0
Initial release.
Products
Intersil Corporation is a leader in the design and manufacture of high-performance analog semiconductors. The Company's products
address some of the industry's fastest growing markets, such as, flat panel displays, cell phones, handheld products, and notebooks.
Intersil's product families address power management and analog signal processing functions. Go to www.intersil.com/products for a
complete list of Intersil product families.
*For a complete listing of Applications, Related Documentation and Related Parts, please see the respective device information page
on intersil.com: ZL2103
To report errors or suggestions for this datasheet, please go to www.intersil.com/askourstaff
FITs are available from our website at http://rel.intersil.com/reports/search.php
For additional products, see www.intersil.com/product_tree
Intersil products are manufactured, assembled and tested utilizing ISO9000 quality systems as noted
in the quality certifications found at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time
without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be
accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third
parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
This product is subject to a license from Power One, Inc. related to digital power technology as set forth in U.S. Patent No. 7,000,125 and other related patents
owned by Power One, Inc. These license rights do not extend to stand-alone POL regulators unless a royalty is paid to Power One, Inc.
For information regarding Intersil Corporation and its products, see www.intersil.com
27
FN6966.5
May 3, 2011
ZL2103
Package Outline Drawing
L36.6x6C
36 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE
Rev 0, 4/10
4X 4.0
6.00
36X 0.50
A
B
28
6
PIN 1
INDEX AREA
36
27
6
PIN #1
INDEX AREA
6.00
1
4 .10 ± 0.10
9
19
(4X)
0.15
18
10
TOP VIEW
36X 0.60 ± 0.10
36X 0.25 4
0.10 M C A B
BOTTOM VIEW
SEE DETAIL "X"
0.10 C
MAX 1.00
C
0.08 C
( 5. 60 TYP )
( 36 X 0 . 50 )
SIDE VIEW
(
4. 10 )
(36X 0.25 )
C
( 36X 0.80 )
0 . 2 REF
5
0 . 00 MIN.
0 . 05 MAX.
TYPICAL RECOMMENDED LAND PATTERN
DETAIL "X"
NOTES:
1.
Dimensions are in millimeters.
Dimensions in ( ) for Reference Only.
2.
Dimensioning and tolerancing conform to ASME Y14.5m-1994.
3.
Unless otherwise specified, tolerance : Decimal ± 0.05
4.
Dimension applies to the metallized terminal and is measured
between 0.15mm and 0.30mm from the terminal tip.
5.
Tiebar shown (if present) is a non-functional feature.
6.
The configuration of the pin #1 identifier is optional, but must be
located within the zone indicated. The pin #1 identifier may be
7.
JEDEC reference drawing: MO-220VJJD.
either a mold or mark feature.
28
FN6966.5
May 3, 2011
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