2- to 4-Phase Synchronous Buck Controller

6-Bit Programmable 2- to 4-Phase
Synchronous Buck Controller
ADP3196
FUNCTIONAL BLOCK DIAGRAM
FEATURES
VCC
Desktop PC power supplies for next generation
AMD processors
VRM modules
RAMPADJ
13
SHUNT
REGULATOR
SET
+
CMP
–
GND 18
+
CMP
–
–
800mV
EN
19 OD
OSCILLATOR
UVLO
SHUTDOWN
+
1
CURRENT
BALANCING
CIRCUIT
–
1.8V
CSREF
+
+
CMP
–
EN
RESET
30 PWM1
RESET
29 PWM2
RESET
28 PWM3
2-/3-/4-PHASE
DRIVER LOGIC
+
CMP
–
+
DAC – 250mV
–
2
DELAY
CROWBAR
25 SW1
VRMHOT
9
VRM_OFF
8
24 SW2
THERMAL
THROTTLING
CONTROL
23 SW3
22 SW4
17 CSCOMP
ILIMIT 11
DELAY
CURRENT
MEASUREMENT
AND LIMIT
7
+
–
GENERAL DESCRIPTION
1
The ADP3196 is a highly efficient multiphase synchronous
buck switching regulator controller optimized for converting a
12 V main supply into the core supply voltage required by high
performance Advanced Micro Devices, Inc. (AMD) processors.
It uses an internal 6-bit DAC to read a voltage identification
(VID) code directly from the processor, which is used to set the
output voltage between 0.3750 V and 1.55 V.
This device uses a multimode PWM architecture to drive the
logic-level outputs at a programmable switching frequency that
can be optimized for VR size and efficiency. The phase
relationship of the output signals can be programmed to provide
2-, 3-, or 4-phase operation, allowing for the construction of up to
four complementary buck switching stages.
The ADP3196 supports a programmable slope function to
adjust the output voltage as a function of the load current so
that it is always optimally positioned for a system transient.
This can be disabled by connecting Pin LLSET to Pin CSREF.
1
Protected by U.S. Patent Number 6,683,441; others patents pending.
©2008 SCILLC. All rights reserved.
January 2008 – Rev. 1
27 PWM4
RESET
CURRENT
LIMIT
PWRGD
TTSENSE 10
APPLICATIONS
RT
12
31
15 CSREF
16 CSSUM
21 IMON
IREF 20
COMP
FB
+
+
PRECISION
REFERENCE
FBRTN
4
–
5
14 LLSET
–
3
SOFT START
CONTROL
6
SS
VID DAC
34
35
VID5 VID4
36
37
38
39
VID3
VID2
VID1
VID0
ADP3196
06371-001
Selectable 2-, 3-, or 4-phase operation at up to 1 MHz
per phase
±10 mV worst-case differential sensing error over
temperature
Logic-level PWM outputs for interface to external
high power drivers
Enhanced PWM flex mode for excellent load transient
performance
Active current balancing between all output phases
Built-in power-good/crowbar blanking supports on-the-fly
VID code changes
Digitally programmable 0.3750 V to 1.55 V output
Programmable short-circuit protection with programmable
latch-off delay
Figure 1. Functional Block Diagram
The ADP3196 also provides accurate and reliable short-circuit
protection, adjustable current limiting, and a delayed powergood output that accommodates on-the-fly output voltage
changes requested by the CPU. The ADP3196 has a built-in
shunt regulator that allows the part to be connected to the 12 V
system supply through a series resistor.
The ADP3196 is specified over the extended commercial
temperature range of 0°C to +85°C and is available in a
40-lead LFCSP.
Publication Order Number:
ADP3196/D
ADP3196
TABLE OF CONTENTS
Features...............................................................................................1
Output Current Sensing.............................................................11
Applications .......................................................................................1
Active Impedance Control Mode .............................................11
General Description..........................................................................1
Current Control Mode and Thermal Balance.........................11
Functional Block Diagram...............................................................1
Voltage Control Mode ................................................................12
Table of Contents...............................................................................2
Current Reference.......................................................................12
Revision History................................................................................2
Enhanced PWM Mode...............................................................12
Specifications .....................................................................................3
Delay Timer .................................................................................12
Test Circuits .......................................................................................5
Soft Start.......................................................................................12
Absolute Maximum Ratings ............................................................6
Current Limit, Short-Circuit, and Latch-Off Protection.......13
ESD Caution ..................................................................................6
Dynamic VID ..............................................................................14
Pin Configuration and Function Description...............................7
Power-Good Monitoring ...........................................................14
Typical Performance Characteristics..............................................9
Output Crowbar..........................................................................14
Theory of Operation.......................................................................10
Output Enable and UVLO.........................................................14
Start-Up Sequence ......................................................................10
Thermal Monitoring...................................................................14
Phase Detection Sequence .........................................................10
Layout and Component Placement..........................................17
Master Clock Frequency ............................................................11
Outline Dimensions........................................................................18
Output Voltage Differential Sensing ........................................11
Ordering Guide ...........................................................................18
REVISION HISTORY
01/08 - Rev 1: Conversion to ON Semiconductor
10/06—Revision 0: Initial Version
Rev. 1 | Page 2 of 18 | www.onsemi.com
ADP3196
SPECIFICATIONS
VCC = 5 V, FBRTN = GND, TA = 0°C to 85°C, unless otherwise noted.1
Table 1.
Parameter
REFERENCE CURRENT
Reference Bias Voltage
Reference Bias Current
Symbol
Conditions
Min
Typ
Max
Unit
VIREF
IIREF
RIREF = 100 kΩ
14.25
1.5
15
15.75
V
μA
ERROR AMPLIFIER
Output Voltage Range2
Accuracy
VCOMP
VFB
4.4
10
V
mV
−82
+1
−6
200
mV
LSB
Load Line Positioning Accuracy
Differential Nonlinearity
Input Bias Current
FBRTN Current
Output Current
Gain Bandwidth Product
Slew Rate
LLSET Input Voltage Range
LLSET Input Bias Current
VID INPUTS
Input Low Voltage
Input High Voltage
Input Current
VID Transition Delay Time2
OSCILLATOR
Frequency Range2
Frequency Variation
IFB
IFBRTN
ICOMP
COMP = FB
COMP = FB
20
25
VLLSET
ILLSET
Relative to CSREF
VIL(VID)
VIH(VID)
IIN(VID)
VID(X), VIDSEL
VID(X), VIDSEL
1.4
VID code change to FB change
400
VRT
VRAMPADJ
IRAMPADJ
Input Common-Mode Range
Output Voltage Range
Output Current
Current Limit Latch-Off Delay
Time
IMON Output
CURRENT BALANCE AMPLIFIER
Common-Mode Range
Input Resistance
Input Current
Input Current Matching
CURRENT LIMIT COMPARATOR
ILIMIT Bias Current
ILIMIT Voltage
Maximum Output Voltage
Current Limit Threshold Voltage
Current Limit Setting Ratio
−80
FB forced to VOUT – 3%
RAMPADJ Output Voltage
RAMPADJ Input Current Range
Input Bias Current
Gain Bandwidth Product
Slew Rate
−78
−1
−9
GBW(ERR)
fOSC
fPHASE
VOS(CSA)
IBIAS(CSSUM)
GBW(CSA)
IFB = 0.5 × IIREF
0.05
−10
−7.5
65
500
Output Voltage
CURRENT SENSE AMPLIFIER
Offset Voltage
Relative to nominal DAC output, referenced to FBRTN,
LLSET = CSREF (see Figure 2)
CSREF – LLSET = 80 mV
−250
−10
0.6
TA = 25°C, RT = 205 kΩ, 4 phase
TA = 25°C, RT = 118 kΩ, 4 phase
TA = 25°C, RT = 55 kΩ, 4 phase
RT = 243 kΩ to GND
RAMPADJ – FB, DAC = 1.55 V
CSSUM – CSREF (see Figure 3)
0.25
180
2.1
MHz
kHz
kHz
kHz
V
−50
1
+50
50
mV
μA
−1.0
+1.0
mV
−10
+10
nA
MHz
1.9
CSSUM = CSCOMP
CCSCOMP = 10 pF
200
400
800
2.0
4
220
10
10
0
0.05
ICSCOMP
3.5
3.5
CDELAY = 10 nF
IMON
10 × (CSREF – CSCOMP) > 50mV
−6
ΔISW(X)
SW(X) = 0 V
SW(X) = 0 V
SW(X) = 0 V
−600
10
8
−4
IILIMIT
IILIMIT = 2/3 × IIREF
VILIMIT
RILIMIT = 121kΩ (VILIMIT = IILIMIT × RILIMIT)
VCL
VCSREF – VCSCOMP, RILIMIT = 121 kΩ
VCL/IILIMIT
V/μs
V
V
μA
ms
500
tOC(DELAY)
Rev. 1 | Page 3 of 18 | www.onsemi.com
V
V
μA
ns
−10
CSSUM and CSREF
VSW(X)CM
RSW(X)
ISW(X)
+250
+10
μA
μA
μA
MHz
V/μs
mV
nA
8
+6
%
17
12
+200
26
20
+4
mV
kΩ
9
10
11
1.09
3
80
1.21
1.33
100
82.6
125
μA
%
μA
V
V
mV
mV/V
ADP3196
Parameter
DELAY TIMER
Normal Mode Output Current
Output Current in Current Limit
Threshold Voltage
SOFT START
Output Current (Startup)
Output Current (DAC Code
Change)
ENABLE INPUT
Threshold Voltage
Hysteresis
Input Current
Delay Time
Symbol
Conditions
Min
Typ
Max
Unit
IDELAY
IDELAY(CL)
VDELAY(TH)
IDELAY = IIREF
IDELAY(CL) = 0.25 × IIREF
12
3.0
1.6
15
3.75
1.7
18
4.5
1.8
μA
μA
V
ISS(STARTUP)
During startup, ISS(STARTUP) = 0.25 × IIREF
3
3.75
4.5
μA
ISS(DAC)
DAC code change, ISS(DAC) = 1.25 × IIREF
15
18.75
22.5
μA
750
80
800
100
−1
850
125
mV
mV
VTH(EN)
VHYS(EN)
IIN(EN)
tDELAY(EN)
EN > 950 mV, CDELAY = 10 nF
μA
ms
2
OD OUTPUT
Output Low Voltage
VOL(OD)
Output High Voltage
VOH(OD)
160
4
OD Pull-Down Resistor
THERMAL THROTTLING CONTROL
TTSENSE Voltage Range
TTSENSE Bias Current
TTSENSE VRM_OFF Threshold
Voltage
TTSENSE VRMHOT Threshold
Voltage
TTSENSE Hysteresis
VRM_OFF Output Low Voltage
VRMHOT Output Low Voltage
VOL(VRFAN)
VOL(VRHOT)
I VRFAN (SINK) = −4 mA
I VRHOT (SINK) = −4 mA
POWER-GOOD COMPARATOR
Overvoltage Threshold
VPWRGD(OV)
Undervoltage Threshold
VPWRGD(UV)
Output Low Voltage
Power-Good Delay Time
During Soft Start2
VID Code Changing
VID Code Static
Crowbar Trip Point
Crowbar Delay Time
VID Code Changing
VID Code Static
VOL(PWRGD)
Relative to nominal DAC output; DAC = 0.5 V to 1.55 V
Relative to nominal DAC output; DAC = 0.375 V to 0.4785 V
Relative to nominal DAC output; DAC = 0.5 V to 1.55 V
Relative to nominal DAC output; DAC = 0.375 V to 0.4785 V
IPWRGD(SINK) = −4 mA
PWM OUTPUTS
Output Low Voltage
Output High Voltage
Internally limited
POWER SUPPLY
VCC
DC Supply Current
UVLO Turn On Current
UVLO Threshold Voltage
UVLO Threshold Voltage
IPWM(SINK) = −400 μA
IPWM(SOURCE) = 400 μA
kΩ
5
−111
1.15
μA
V
765
810
855
mV
50
150
150
300
300
mV
mV
mV
250
250
−250
−250
150
300
310
−200
−190
300
mV
mV
mV
mV
mV
1.85
μs
ns
V
200
190
−300
−310
1.75
100
VOL(PWM)
VOH(PWM)
60
−123
1.105
100
Relative to FBRTN
Overvoltage to PWM going low
mV
V
0
−135
1.06
CDELAY = 10 nF
VCROWBAR
tCROWBAR
500
5
2
250
200
1.8
V
ms
μs
ns
250
400
160
5
500
4.0
mV
V
4.65
5
5.55
25
11
V
mA
mA
VSYSTEM = 12 V, RSHUNT = 340Ω (see Figure 2)
VCC
IVCC
6.5
VUVLO
VUVLO
VCC rising
VCC falling
1
All limits at temperature extremes are guaranteed via correlation using standard statistical quality control (SQC).
2
Guaranteed by design or bench characterization, not tested in production.
Rev. 1 | Page 4 of 18 | www.onsemi.com
9
4.1
V
ADP3196
TEST CIRCUITS
12V
680Ω
6-BIT CODE
+
1μF
680Ω
100nF
1.25V
1kΩ
10nF
NC
VID0
VID1
VID2
VID3
VID4
VID5
NC
NC
VCC
EN
PWRGD
FBRTN
FB
COMP
SS
DELAY
VRM_OFF
VRMHOT
TTSENSE
ADP3196
680Ω
PWM1
PWM2
PWM3
PWM4
NC
SW1
SW2
SW3
SW4
IMON
680Ω
VCC
31
FB
4
10kΩ
FBRTN
3
ILIMIT
RT
RAMPADJ
LLSET
CSREF
CSSUM
CSCOMP
GND
OD
IREF
10nF
1
ADP3196
12V
40
LLSET
14
ΔV
100kΩ
CSREF
15
1V
250kΩ
–
+
VID
DAC
GND
20kΩ
100nF
NC = NO CONNECT.
ΔVFB = FBΔV = 80mV – FBΔV = 0mV
Figure 4. Positioning Voltage
Figure 2. Closed-Loop Output Voltage Accuracy
12V
ADP3196
680Ω
680Ω
VCC
31
CSCOMP
17
39kΩ
100nF
CSSUM
16
1kΩ
CSREF
1V
GND
18
VOS =
CSCOMP – 1V
40
06371-003
15
Figure 3. Current Sense Amplifier VOS
Rev. 1 | Page 5 of 18 | www.onsemi.com
06371-004
06371-002
18
ADP3196
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
VCC
FBRTN
PWM3 – PWM4, RAMPADJ
SW1 – SW4
<200 ns
All Other Inputs and Outputs
Storage Temperature
Operating Ambient Temperature Range
Operating Junction Temperature
Thermal Impedance (θJA)
Lead Temperature
Soldering (10 sec)
Infrared (15 sec)
Rating
−0.3 V to +6 V
−0.3 V to +0.3 V
−0.3 V to VCC + 0.3 V
−5 V to +25 V
−10 V to +25 V
−0.3 V to VCC + 0.3 V
−65°C to +150°C
0°C to 85°C
125°C
100°C/W
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only and functional operation of the device at these or
any other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability. Absolute maximum ratings apply individually
only, not in combination. Unless otherwise specified all other
voltages referenced to GND.
ESD CAUTION
300°C
260°C
Rev. 1 | Page 6 of 18 | www.onsemi.com
ADP3196
40
39
38
37
36
35
34
33
32
31
NC
VID0
VID1
VID2
VID3
VID4
VID5
NC
NC
VCC
PIN CONFIGURATION AND FUNCTION DESCRIPTION
PIN 1
INDICATOR
ADP3196
TOP VIEW
(Not to Scale)
30
29
28
27
26
25
24
23
22
21
PWM1
PWM2
PWM3
PWM4
NC
SW1
SW2
SW3
SW4
IMON
NOTES
1. NC = NO CONNECT.
2. THE EXPOSED EPAD ON BOTTOM SIDE OF PACKAGE IS AN
ELECTRICAL CONNECTION AND SHOULD BE SOLDERED TO GROUND.
06371-005
ILIMIT
RT
RAMPADJ
LLSET
CSREF
CSSUM
CSCOMP
GND
OD
IREF
11
12
13
14
15
16
17
18
19
20
EN 1
PWRGD 2
FBRTN 3
FB 4
COMP 5
SS 6
DELAY 7
VRM_OFF 8
VRMHOT 9
TTSENSE 10
Figure 5. Pin Configuration
Table 3. Pin Function Descriptions
Pin No.
1
2
Mnemonic
EN
PWRGD
3
4
FBRTN
FB
5
6
COMP
SS
7
DELAY
8
VRM_OFF
9
VRMHOT
10
TTSENSE
11
ILIMIT
12
RT
13
RAMPADJ
14
LLSET
15
CSREF
16
CSSUM
17
CSCOMP
Description
Power Supply Enable Input. Pulling this pin to GND disables the PWM outputs and pulls the PWRGD output low.
Power-Good Output. Open-drain output that signals when the output voltage is outside of the proper
operating range.
Feedback Return. VID DAC and error amplifier reference for remote sensing of the output voltage.
Feedback Input. Error amplifier input for remote sensing of the output voltage. An external resistor between
this pin and the output voltage sets the no load offset point.
Error Amplifier Output and Compensation Point.
Soft Start Delay Setting Input. An external capacitor connected between this pin and GND sets the soft start
ramp-up time and the VID on-the-fly slew rate.
Delay Timer Setting Input. An external capacitor connected between this pin and GND sets the overcurrent
latch-off delay time, EN delay time, and PWRGD delay time.
VRM_OFF Signal. Open-drain output that asserts when the temperature at the monitoring point connected to
TTSENSE exceeds the VRM_OFF threshold.
Open-drain output that signals when the temperature at the monitoring point connected to TTSENSE exceeds
the maximum operating temperature. For example, this can be connected to the PROCHOT# (a PC system
signal) output from the CPU.
VR Hot Thermal Throttling Sense Input. An NTC thermistor between this pin and GND is used to remotely sense
the temperature at the desired thermal monitoring point.
Current Limit Setpoint. An external resistor from this pin to GND sets the current limit threshold of the
converter.
Frequency Setting Resistor Input. An external resistor connected between this pin and GND sets the oscillator
frequency of the device.
PWM Ramp Current Input. An external resistor from the converter input voltage to this pin sets the internal
PWM ramp.
Output Load Line Programming Input. This pin can be directly connected to CSCOMP, or it can be connected to
the center point of a resistor divider between CSCOMP and CSREF. Connecting LLSET to CSREF disables
positioning.
Current Sense Reference Voltage Input. The voltage on this pin is used as the reference for the current sense
amplifier and the power-good and crowbar functions. This pin should be connected to the common point of
the output inductors.
Current Sense Summing Node. External resistors from each switch node to this pin sum the average inductor
currents together to measure the total output current.
Current Sense Compensation Point. A resistor and capacitor from this pin to CSSUM determines the gain of the
current sense amplifier and the positioning loop response time.
Rev. 1 | Page 7 of 18 | www.onsemi.com
ADP3196
Pin No.
18
19
Mnemonic
GND
OD
20
IREF
21
22 to 25
IMON
SW4 to SW1
26, 32,
33, 40
27 to 30
NC
31
VCC
34 to 39
VID5 to VID0
PWM4 to
PMW1
Description
Ground. All internal biasing and the logic output signals of the device are referenced to this ground.
Output Disable Logic Output. This pin is actively pulled low when the ADP3196 EN input is low or when VCC is
below its UVLO threshold to signal to the driver IC that the driver high-side and low-side outputs should go low.
Current Reference Input. An external resistor from this pin to ground sets the reference current for IFB, IDELAY, ISS,
IILIMIT and ITTSENSE.
Analog Output. Represents total load current.
Current Balance Inputs. Inputs for measuring the current level in each phase. The SW pins of unused phases
should be left open.
No Connection.
Logic Level PWM Outputs. Each output is connected to the input of an external MOSFET driver, such as the
ADP3120A. Connecting the PWM3 and/or PWM4 outputs to the ADP3196 VCC pin causes that phase to turn off,
allowing the ADP3196 to operate as a 2-, 3-, or 4-phase controller.
A 340 Ω resistor should be placed between the 12 V system supply and the VCC pin. The internal shunt
regulator maintains VCC = 5 V.
Voltage Code DAC Inputs. These six pins are pulled down to GND, providing a logic zero if left open. When in normal
operation mode, the DAC output programs the FB regulation voltage from 0.3750 V and 1.55 V (see Table 4).
Rev. 1 | Page 8 of 18 | www.onsemi.com
ADP3196
TYPICAL PERFORMANCE CHARACTERISTICS
7200
6400
4800
4000
3200
2400
1600
800
0
0
100
200
300
400
500
600
700
RT (kΩ)
800
900
06371-015
FREQUENCY (kHz)
5600
Figure 6. Master Clock Frequency vs. RT
Rev. 1 | Page 9 of 18 | www.onsemi.com
ADP3196
THEORY OF OPERATION
Multiphase operation is important for producing the high
currents and low voltages demanded by today’s microprocessors.
Handling the high currents in a single-phase converter places
high thermal demands on the components in the system, such
as the inductors and MOSFETs.
The multimode control of the ADP3196 ensures a stable, high
performance topology for the following:
•
Balancing currents and thermals between phases
•
High speed response at the lowest possible switching
frequency and output decoupling
•
Minimizing thermal switching losses by utilizing lower
frequency operation
5V
SUPPLY
UVLO
THRESHOLD
0.8V
ADP3196 EN
VDELAY(TH)
(1.7V)
DELAY
VVID
SS
VVID
TD1
VCC_CORE
TD2
VR READY
(ADP3196 PWRGD)
CPU
VID INPUTS
TD3
VID INVALID
VID VALID
06371-006
The ADP3196 combines a multimode, fixed frequency PWM
control with multiphase logic outputs for use in 2-, 3-, and
4-phase synchronous buck CPU core supply power converters.
The internal VID DAC is designed to interface with the AMD
6-bit CPUs.
Figure 7. System Start-Up Sequence
•
Tight load line regulation and accuracy
PHASE DETECTION SEQUENCE
•
High current output due to 4-phase operation
•
Reduced output ripple due to multiphase cancellation
•
PC board layout noise immunity
•
Ease of use and design due to independent component
selection
•
Flexibility in operation for tailoring design to low cost or
high performance
During startup, the number of operational phases and their
phase relationship is determined by the internal circuitry that
monitors the PWM outputs. Normally, the ADP3196 operates
as a 4-phase PWM controller. Connecting the PWM4 pin to the
VCC pin programs 3-phase operation while connecting the
PWM4 pin and the PWM3 pin to the VCC pin programs
2-phase operation.
START-UP SEQUENCE
The ADP3196 follows the start-up sequence shown in Figure 7.
After both the EN and UVLO conditions are met, the DELAY pin
goes through one cycle (TD1). The first four clock cycles of TD2
are blanked from the PWM outputs and used for phase detection as
explained in the Phase Detection Sequence section. Then, the soft
start ramp is enabled (TD2) and the output comes up to the
programmed DAC Voltage.
After TD2 has been completed and the PWRGD masking time
(equal to VID on-the-fly masking) is finished, a second ramp
on the DELAY pin sets the PWRGD blanking (TD3).
While EN is low and prior to soft start, Pins PWM3 and PWM4
sink approximately 100 μA. An internal comparator checks the
voltage of each pin vs. a threshold of 3 V. If the pin is tied to
VCC, it is above the threshold. Otherwise, an internal current
sink pulls the pin to GND, which is below the threshold. PWM1
and PWM2 are low during the phase detection interval, which
occurs during the first four clock cycles of TD2. After this time,
if the remaining PWM outputs are not pulled to VCC, the
100 μA current sink is removed and they function as normal
PWM outputs. If they are pulled to VCC, the 100 μA current
source is removed and the outputs are put into a high
impedance state.
The PWM outputs are logic-level devices intended for driving
external gate drivers, such as the ADP3120A. Because each
phase is monitored independently, operation approaching 100%
duty cycle is possible. In addition, more than one output can be
on at the same time to allow overlapping phases.
Rev. 1 | Page 10 of 18 | www.onsemi.com
ADP3196
MASTER CLOCK FREQUENCY
The clock frequency of the ADP3196 is set with an external
resistor connected from the RT pin to ground. The frequency
follows the graph in Figure 6. To determine the frequency per
phase, the clock is divided by the number of phases in use. If all
phases are in use, divide by 4. If PWM4 is tied to VCC, then
divide the master clock by 3 for the frequency of the remaining
phases. If PWM3 and PWM4 are tied to VCC, then divide by 2.
OUTPUT VOLTAGE DIFFERENTIAL SENSING
The ADP3196 combines differential sensing with a high
accuracy VID DAC and reference and a low offset error
amplifier. This maintains a worst-case specification of ±10 mV
differential sensing error over its full operating output voltage
and temperature range. The output voltage is sensed between
the FB pin and the FBRTN pin. Pin FB should be connected
through a resistor to the regulation point, usually the remote
sense pin of the microprocessor. Pin FBRTN should be
connected directly to the remote sense ground point. The
internal VID DAC and precision reference are referenced to
FBRTN, which has a minimal current of 65 μA to allow
accurate remote sensing. The internal error amplifier compares
the output of the DAC to the FB pin to regulate the output
voltage.
OUTPUT CURRENT SENSING
The ADP3196 provides a dedicated current sense amplifier
(CSA) to monitor the total output current for proper voltage
positioning vs. load current and for current limit detection.
Sensing the load current at the output gives the total average
current being delivered to the load, which is an inherently more
accurate method than peak current detection or sampling the
current across a sense element, such as the low-side MOSFET.
This amplifier can be configured several ways depending on the
objectives of the system as follows:
•
Output inductor DCR sensing without a thermistor for
lowest cost
•
Output inductor DCR sensing with a thermistor for
improved accuracy with tracking of inductor temperature
•
Sense resistors for highest accuracy measurements
The positive input of the CSA is connected to the CSREF pin,
which is connected to the output voltage. The inputs to the
amplifier are summed together through resistors from the
sensing element, such as the switch node side of the output
inductors, to the inverting input, CSSUM. The feedback resistor
between CSCOMP and CSSUM sets the gain of the amplifier,
and a filter capacitor is placed in parallel with this resistor. The
gain of the amplifier is programmable by adjusting the feedback
resistor.
An additional resistor divider connected between CSREF and
CSCOMP, with the midpoint connected to LLSET, can be used
to set the load line required by the microprocessor. The current
information is then given as CSREF – LLSET. This difference
signal is used internally to offset the VID DAC for voltage
positioning. The difference between CSREF and CSCOMP is then
used as a differential input for the current-limit comparator. This
allows the load line to be set independent of the current-limit
threshold. In the event that the current-limit threshold and load
line are not independent, the resistor divider between CSREF and
CSCOMP can be removed and the CSCOMP pin can be directly
connected to the LLSET pin. To disable voltage positioning entirely
(that is, no load line), connect LLSET to CSREF.
To provide the best accuracy for sensing current, the CSA is
designed to have a low offset input voltage. In addition, the
sensing gain is determined by external resistors to make it
extremely accurate.
ACTIVE IMPEDANCE CONTROL MODE
For controlling the dynamic output voltage droop as a function
of output current, a signal proportional to the total output
current at the LLSET pin can be scaled to be equal to the droop
impedance of the regulator times the output current. This
droop voltage is then used to set the input control voltage to the
system. The droop voltage is subtracted from the DAC
reference input voltage directly to tell the error amplifier where
the output voltage should be. This allows enhanced feed forward
response.
CURRENT CONTROL MODE AND THERMAL
BALANCE
The ADP3196 has individual inputs (SW1 to SW4) for each
phase that are used for monitoring the current in each phase.
This information is combined with an internal ramp to create a
current balancing feedback system that has been optimized for
initial current balance accuracy and dynamic thermal balancing
during operation. This current balance information is independent
of the average output current information used for positioning
described previously in the Output Current Sensing section.
The magnitude of the internal ramp can be set to optimize the
transient response of the system. It also monitors the supply
voltage for feed forward control for changes in the supply. A
resistor connected from the power input voltage to the
RAMPADJ pin determines the slope of the internal PWM ramp.
External resistors can be placed in series with individual phases
to create an intentional current imbalance, if desired, such as
when one phase has better cooling and can support higher
currents. Resistors RSW1 through RSW4 (see Figure 11) can be
used for adjusting thermal balance. It is best to have the ability
to add these resistors during the initial design, therefore, ensure
that placeholders are provided in the layout.
Rev. 1 | Page 11 of 18 | www.onsemi.com
ADP3196
To increase the current in any given phase, make RSW for that
phase larger (make RSW = 0 for the hottest phase and do not
change during balancing). Increasing RSW to only 500 Ω makes
a substantial increase in phase current. Increase each RSW value
by small amounts to achieve balance, starting with the coolest
phase first.
VOLTAGE CONTROL MODE
A high gain, high bandwidth voltage mode error amplifier is
used for the voltage mode control loop. The control input
voltage to the positive input is set via the VID logic according to
the voltages listed in Table 4.
The voltage is also offset by the droop voltage for active
positioning of the output voltage as a function of current,
commonly known as active voltage positioning. The output of
the amplifier is the COMP pin, which sets the termination
voltage for the internal PWM ramps.
The negative input (FB) is tied to the output sense location with
Resistor RB and is used for sensing and controlling the output
voltage at this point. A current source (equal to IREF/2) flows
through RB into the FB pin and is used for setting the no load
offset voltage from the VID voltage. The no load offset is
positive with respect to the VID DAC. The main loop
compensation is incorporated into the feedback network
between FB and COMP.
CURRENT REFERENCE
The IREF pin is used to set an internal current reference. This
reference current sets IFB, IDELAY, ISS, ILIMIT, and ITTSENSE. A resistor
to ground programs the current based on the 1.5 V output.
IREF =
1.5 V
RIREF
Typically, RIREF is set to 100 kΩ to program IREF = 15 μA. The
following currents are then equal to:
IFB = 1/2 (IREF) = 7.5 μA
IDELAY = IREF = 15 μA
ISS(STARTUP) = 1/4 (IREF) = 3.75 μA
ISS(DAC) = 5/4 (IREF) = 18.75 μA
ILIMIT = 2/3 (IREF) = 10 μA
ITTSENSE = 8 (IREF) = 120 μA
DELAY TIMER
The delay times for the start-up timing sequence are set with a
capacitor from the DELAY pin to ground. In UVLO or when
EN is logic low, the DELAY pin is held at ground. After the
UVLO and EN signals are asserted, the first delay time (TD1 in
Figure 7) is initiated. A current flows out of the DELAY pin to
charge CDLY. This current is equal to IREF, which is normally
15 μA. A comparator monitors the DELAY voltage with a
threshold of 1.7 V.
The delay time is therefore set by the IREF current charging a
capacitor from 0 V to 1.7 V. This DELAY pin is used for two
delay timings (TD1 and TD3) during the start-up sequence. In
addition, DELAY is used for timing the current limit latch off as
explained in the Current Limit, Short-Circuit, and Latch-Off
Protection section.
SOFT START
The soft start ramp rates for the output voltage are set up with a
capacitor from the soft start (SS) pin to ground. During startup,
the SS pin sources a current of 3.75 μA. After startup, when a
DAC code change occurs, the SS pin sinks or sources an
18.75 μA current to control the rate at which the output voltage
can transition up or down.
During startup (after TD1 and the phase detection cycle are
complete), the SS time (TD2 in Figure 7) starts. The SS pin is
disconnected from GND and the capacitor is charged up to the
programmed DAC voltage by the SS amplifier, which has an
output current equal to one quarter IREF (normally 3.75 μA).
The voltage at the FB pin follows the ramping voltage on the
SS pin, limiting the inrush current during startup. The soft start
time depends on the value of the initial DAC voltage and CSS.
Note that the DAC code must be set before the ADP3196 is
enabled.
Once the SS voltage is within 50 mV of the programmed DAC
voltage, the power-good delay time (TD3) starts. Once TD2 has
completed, the soft start current changes to 18.75 μA. If the
programmed DAC code changes after startup, then the SS pin
sources or sinks a current of 18.75 μA to or from the SS
capacitor. This occurs until the SS voltage is within 50 mV of
the newly programmed DAC voltage.
If EN is taken low or VCC drops below UVLO, DELAY and SS are
reset to ground in preparation for another soft start cycle.
ENHANCED PWM MODE
Enhanced PWM mode is intended to improve the transient
response of the ADP3196 to a load stepup. In previous
generations of controllers, when a load stepup occurred, the
controller had to wait until the next turn on of the PWM signal
to respond to the load change. Enhanced PWM mode allows
the controller to respond immediately when a load stepup
occurs. This allows the phases to respond when the load
increase transition takes place.
Rev. 1 | Page 12 of 18 | www.onsemi.com
ADP3196
Figure 8 shows typical start-up waveforms for the ADP3196,
while Figure 9 shows a typical DAC code change waveform.
1
A comparator monitors the DELAY voltage and shuts off the
controller when the voltage reaches 1.7 V. The current limit
latch-off delay time is therefore set by the current of IREF/4
charging the delay capacitor from 0 V to 1.7 V. This delay is
four times longer then the delay time during the start-up
sequence.
The current limit delay time only starts after the TD3 has
completed. If there is a current limit during startup, the
ADP3196 goes through TD1 to TD3, and then starts the
latch-off time. Because the controller continues to cycle the
phases during the latch-off delay time, if the short is removed
before the 1.7 V threshold is reached, the controller returns to
normal operation and the DELAY capacitor is reset to GND.
2
4
CH1 1V
CH3 2V
CH2 1V
CH4 10V
M 2ms
A CH3
600mV
06371-007
3
Figure 8. Typical Start-Up Waveforms Channel 1: CSREF,
Channel 2: SS, Channel 3: DELAY, Channel 4: Phase 1 Switch Node
The latch-off function can be reset by either removing and
reapplying the supply voltage to the ADP3196, or by toggling
the EN pin low for a short time. To disable the short-circuit
latch-off function, an external resistor should be placed in
parallel with CDLY. This prevents the DELAY capacitor from
charging up to the 1.7 V threshold. The addition of this resistor
causes a slight increase in the delay times.
During startup when the output voltage is below 200 mV, a
secondary current limit is active. This is necessary because the
voltage swing of CSCOMP cannot go below ground. This
secondary current limit controls the internal COMP voltage to
the PWM comparators to 1.5 V. This limits the voltage drop
across the low-side MOSFETs through the current balance
circuitry.
1
3
CH1 500mV CH2 500mV
CH3 5V
M 2ms
A CH1
980mV
06371-008
2
Figure 9. Typical DAC Code Change Waveforms Channel 1: CSREF,
Channel 2: SS, Channel 3: Phase 1 Switch Node
An inherent per phase current limit protects individual phases
if one or more phases stop functioning because of a faulty
component. This limit is based on the maximum normal mode
COMP voltage. Typical overcurrent latch-off waveforms are
shown in Figure 10.
CURRENT LIMIT, SHORT-CIRCUIT, AND LATCHOFF PROTECTION
This current, through the external resistor, sets the ILIMIT
voltage, which is internally scaled to give a current limit
threshold of 82.6 mV/V. If the difference in voltage between
CSREF and CSCOMP rises above the current limit threshold,
the internal current limit amplifier controls the internal COMP
voltage to maintain the average output current at the limit.
If the limit is reached and TD3 has completed, a latch-off delay
time starts, and the controller shuts down if the fault is not
removed. The current limit delay time shares the DELAY pin
timing capacitor with the start-up sequence timing. However,
during current limit, the DELAY pin current is reduced to IREF/4.
1
2
3
4
CH1 1V
CH3 2V
CH2 2V
CH4 10V
M 2ms
A CH1
600mV
06371-009
The ADP3196 compares a programmable current limit setpoint
to the voltage from the output of the current sense amplifier.
The level of current limit is set with the resistor from the
ILIMIT pin to ground. During operation, the current from
ILIMIT is equal to 2/3 of IREF, giving 10 μA normally.
Figure 10. Overcurrent Latch-Off Waveforms Channel 1: CSREF,
Channel 2: COMP, Channel 3: DELAY, Channel 4: Phase 1 Switch Node
Rev. 1 | Page 13 of 18 | www.onsemi.com
ADP3196
DYNAMIC VID
The ADP3196 has the ability to respond to dynamically
changing VID inputs while the controller is running. This
allows the output voltage to change while the supply is running
and supplying current to the load. This is commonly referred to
as VID on-the-fly (OTF). A VID OTF can occur under either
light or heavy load conditions. The processor signals the
controller by changing the VID inputs in multiple steps from
the start code to the finish code. This change can be positive or
negative.
When a VID input changes state, the ADP3196 detects the
change and ignores the DAC inputs for a minimum of 400 ns.
This time prevents a false code due to logic skew while the six
VID inputs are changing. Additionally, the first VID change
initiates the PWRGD and CROWBAR blanking functions for a
minimum of 100 μs to prevent a false PWRGD or CROWBAR
event. Each VID change resets the internal timer.
POWER-GOOD MONITORING
The power-good comparator monitors the output voltage via
the CSREF pin. The PWRGD pin is an open-drain output
whose high level, when connected to a pull-up resistor,
indicates that the output voltage is within the nominal limits
specified based on the VID voltage setting. PWRGD goes low if
the output voltage is outside of this specified range, if the VID
DAC inputs are in no CPU mode, or if the EN pin is pulled low.
PWRGD is blanked during a VID OTF event for a period of
200 μs to prevent false signals during the time the output is
changing.
The PWRGD circuitry also incorporates an initial turn-on
delay time (TD3) based on the DELAY timer. Prior to the SS
voltage reaching the programmed VID DAC voltage and the
PWRGD masking time finishing, the PWRGD pin is held low.
Once the SS pin is within 50 mV of the programmed DAC
voltage, the capacitor on the DELAY pin begins to charge.
A comparator monitors the DELAY voltage and enables
PWRGD when the voltage reaches 1.7 V. The PWRGD delay
time is set, therefore, by a current of IREF charging a capacitor
from 0 V to 1.7 V.
OUTPUT CROWBAR
To protect the load and output components of the supply, the
PWM outputs are driven low which turns on the low-side
MOSFETs when the output voltage exceeds the upper crowbar
threshold.
Turning on the low-side MOSFETs pulls down the output as the
reverse current builds up in the inductors. If the output
overvoltage is due to a short in the high-side MOSFET, this
action current limits the input supply or blows its fuse,
protecting the microprocessor from being destroyed.
OUTPUT ENABLE AND UVLO
For the ADP3196 to begin switching, the input supply (VCC) to
the controller must be higher than the UVLO threshold, the
EN pin must be higher than its 0.8 V threshold, and the DAC
code must be valid. This initiates a system start-up sequence. If
either UVLO or EN is less than their respective thresholds, the
ADP3196 is disabled. This holds the PWM outputs at ground,
shorts the DELAY capacitor to ground, and forces PWRGD,
and OD signals low.
In the application circuit, the OD pin should be connected to
the OD inputs of the ADP3120A drivers. Grounding OD
disables the drivers such that both DRVH and DRVL are
grounded. This feature is important in preventing the discharge
of the output capacitors when the controller is shut off. If the
driver outputs are not disabled, a negative voltage can be
generated during output due to the high current discharge of
the output capacitors through the inductors.
THERMAL MONITORING
The ADP3196 includes a thermal monitoring circuit to detect
when a point on the VR has exceeded two different userdefined temperatures. The thermal monitoring circuit requires
an NTC thermistor to be placed between TTSENSE and GND.
A fixed current of 8 × IREF (normally giving 123 μA) is sourced
out of the TTSENSE pin and into the thermistor. The current
source is internally limited to 5 V. An internal circuit compares
the TTSENSE voltage to a 1.105 V and a 0.81 V threshold and
outputs an open-drain signal at the VRM_OFF and VRMHOT
outputs, respectively.
The VRM_HOT open-drain output goes high once the voltage
on the TTSENSE pin goes below the VRM_HOT thresholds
and signals the system that an overtemperature event has
occurred. The VRM_OFF output asserts when the voltage on
the TTSENSE pin exceeds the VRM_OFF threshold. Because
the TTSENSE voltage changes slowly with respect to time,
50 mV of hysteresis is built into these comparators. The thermal
monitoring circuitry does not depend on EN and is active when
UVLO is above its threshold. When UVLO is below its
threshold, VRFAN and VRHOT are forced low.
Rev. 1 | Page 14 of 18 | www.onsemi.com
ADP3196
Table 4. VID Codes
OUTPUT
1.550
1.525
1.500
1.475
1.450
1.425
1.400
1.375
1.350
1.325
1.300
1.275
1.250
1.225
1.200
1.175
1.150
1.125
1.100
1.075
1.050
1.025
1.000
0.975
0.950
0.925
0.900
0.875
0.850
0.825
0.800
0.775
VID5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
VID4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
VID3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
VID2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
VID1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
VID0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
OUTPUT
0.7625
0.7500
0.7375
0.7250
0.7125
0.7000
0.6875
0.6750
0.6625
0.6500
0.6375
0.6250
0.6125
0.6000
0.5875
0.5750
0.5625
0.5500
0.5375
0.5250
0.5125
0.5000
0.4875
0.4750
0.4625
0.4500
0.4375
0.4250
0.4125
0.4000
0.3875
0.3750
Rev. 1 | Page 15 of 18 | www.onsemi.com
VID5
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
VID4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
VID3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
VID2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
VID1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
VID0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Figure 11.Typical 4-Phase Application Circuit
Rev. 1 | Page 16 of 18 | www.onsemi.com
2
1
R3
1Ω
RA
18.7kΩ
CDLY
18nF
CA
630pF
CFB
16pF
RTH1
100kΩ, 5%
NTC
CSS
10nF
C5
1nF
C6
0.1μF
1
RT
130kΩ
1%
RLIM
160kΩ
1%
EN
PWRGD
FBRTN
FB
COMP
SS
DELAY
VRM_OFF
VRMHOT
TTSENSE
40
+
C4
1μF
680Ω
FROM CPU
C3
100μF
(C3 OPTIONAL)
680Ω
12V
C2
+
ADP3196
U1
C7
1nF
RPH3
RCS1
RCS2
35.7kΩ 88.7kΩ 140kΩ
1%
CONNECT NEAR EACH INDUCTOR.
CCS2
1nF
5% NPO
CCS1
1nF
5% NPO
RSW21
RPH4
140kΩ
1%
RSW41
RSW3 1
RIREF
100kΩ
PWM1
PWM2
PWM3
PWM4
NC
SW1
SW2
SW3
SW4
IMON
FOR A DESCRIPTION OF OPTIONAL RSW RESISTORS, SEE THE THEORY OF OPERATION SECTION.
C8
1nF
RB
2kΩ
CB
630pF
POWER GOOD
VRM_OFF
VRMHOT
VTT I/O
R2
169kΩ
1%
1μF
1kΩ
C1
+
NC
VID0
VID1
VID2
VID3
VID4
VID5
NC
NC
VCC
ILIMIT
RT
RAMPADJ
LLSET
CSREF
CSSUM
CSCOMP
GND
OD
IREF
VIN
RTN
2700μF/16V/3.3A×2
SANYO MV-WX SERIES
RPH2
140kΩ
1%
RSW1 1
RPH1
140kΩ
1%
C22
4.7μF
D5
1N4148
C18
4.7μF
D4
1N4148
C14
4.7μF
D3
1N4148
C10
4.7μF
D2
1N4148
C9
18nF
DRVL
C13
18nF
OD
VCC
R5
2.2Ω
3
4
C17
18nF
DRVL
PGND
SW
DRVH
5
6
7
8
IN
OD
3
6
PGND
C21
18nF
5
7
SW
DRVL
8
DRVH
6
5
DRVL
VCC
4
7
SW
PGND
8
DRVH
OD
IN
2
3
BST
1
C23
U5
ADP3120A 10nF
R7
2.2Ω
VCC
BST
C19
U4
ADP3120A 10nF
R6
2.2Ω
VCC
OD
IN
BST
2
4
5
6
7
8
U3
C15
ADP3120A 10nF
1
4
3
2
1
PGND
IN
2
SW
BST
1
DRVH
C11
U2
ADP3120A 10nF
R4
2.2Ω
Q11
IPD09N03L
Q8
IPD09N03L
Q5
IPD09N03L
Q2
IPD09N03L
Q12
IPD09N03L
L5
280nH/1.4mΩ
Q10
IPD09N03L
C24
4.7μF
Q9
IPD09N03L
L4
280nH/1.4mΩ
Q7
IPD09N03L
C20
4.7μF
Q6
IPD09N03L
L3
280nH/1.4mΩ
Q4
IPD09N03L
C16
4.7μF
Q3
IPD09N03L
+
C25
RTH2
100kΩ, 5%
NTC
10Ω2
10Ω2
10Ω2
10Ω2
+
C32
560μF/4V × 7
L2
280nH/1.4mΩ SANYO SEPC SERIES
5mΩ EACH
C12
4.7μF
Q1
IPD09N03L
VSS(SENSE)
VCC(SENSE)
10μF × 8
MLCC
VCC(CORE) RTN
VCC(CORE)
0.375V TO 1.55V
100A TDC
06371-010
VIN
12V
L1
370nH
18A
ADP3196
ADP3196
LAYOUT AND COMPONENT PLACEMENT
The following guidelines are recommended for optimal
performance of a switching regulator in a PC system.
General Recommendations
For good results, a PCB with at least four layers is recommended.
This provides the needed versatility for control circuitry
interconnections with optimal placement, power planes for
ground, input and output power, and wide interconnection
traces in the remainder of the power delivery current paths.
Keep in mind that each square unit of 1-ounce copper trace
has a resistance of ~0.53 mΩ at room temperature.
Whenever high currents must be routed between PCB layers,
use vias liberally to create several parallel current paths, so the
resistance and inductance introduced by these current paths is
minimized and the via current rating is not exceeded.
If critical signal lines (including the output voltage sense lines of
the ADP3196) must cross through power circuitry, it is best to
interpose a signal ground plane between those signal lines and
the traces of the power circuitry. This serves as a shield to
minimize noise injection into the signals at the expense of
making signal ground a bit noisier.
An analog ground plane should be used around and under the
ADP3196 as a reference for the components associated with the
controller. This plane should be tied to the nearest output
decoupling capacitor ground and should not be tied to any other
power circuitry to prevent power currents from flowing into it.
The components around the ADP3196 should be located close
to the controller with short traces. The most important traces to
keep short and away from other traces are the FB pin and CSSUM
pin. The output capacitors should be connected as close as
possible to the load (or connector), for example, a microprocessor core, that receives the power. If the load is distributed, the
capacitors should also be distributed and generally be in
proportion to where the load tends to be more dynamic.
Avoid crossing any signal lines over the switching power path loop
(described in the Power Circuitry Recommendations section).
Power Circuitry Recommendations
The switching power path should be routed on the PCB to
encompass the shortest possible length to minimize radiated
switching noise energy (EMI) and conduction losses in the
board. Failure to take proper precautions often results in EMI
problems for the entire PC system and noise-related operational
problems in the power converter control circuitry. The switching
power path is the loop formed by the current path through the
input capacitors and the power MOSFETs, including all
interconnecting PCB traces and planes. Using short and wide
interconnection traces is especially critical in this path for two
reasons: it minimizes the inductance in the switching loop,
which can cause high energy ringing; and it accommodates the
high current demand with minimal voltage loss.
When a power dissipating component, for example, a power
MOSFET, is soldered to a PCB, it is recommended to liberally
use the vias, both directly on the mounting pad and immediately
surrounding it. Two important reasons for this are improved
current rating through the vias and improved thermal performance from vias extended to the opposite side of the PCB, where a
plane can more readily transfer the heat to the air. Make a
mirror image of any pad being used to heat sink the MOSFETs
on the opposite side of the PCB to achieve the best thermal
dissipation in the air around the board. To further improve
thermal performance, use the largest possible pad area.
The output power path should also be routed to encompass a
short distance. The output power path is formed by the current
path through the inductor, the output capacitors, and the load.
For best EMI containment, a solid power ground plane should
be used as one of the inner layers extending fully under all the
power components.
Signal Circuitry Recommendations
The output voltage is sensed and regulated between the FB pin
and the FBRTN pin, which connect to the signal ground at the
load. To avoid differential mode noise pickup in the sensed
signal, the loop area should be small. Thus, the FB trace and
FBRTN trace should be routed adjacent to each other on top
of the power ground plane back to the controller.
The feedback traces from the switch nodes should be connected
as close as possible to the inductor. The CSREF signal should be
connected to the output voltage at the nearest inductor to the
controller.
Rev. 1 | Page 17 of 18 | www.onsemi.com
ADP3196
OUTLINE DIMENSIONS
6.00
BSC SQ
0.60 MAX
0.60 MAX
31
30
PIN 1
INDICATOR
TOP
VIEW
0.50
BSC
5.75
BCS SQ
0.50
0.40
0.30
12° MAX
1.00
0.85
0.80
PIN 1
INDICATOR
40
1
4.25
4.10 SQ
3.95
EXPOSED
PAD
(BOTTOM VIEW)
21
20
10
11
0.25 MIN
4.50
REF
0.80 MAX
0.65 TYP
0.05 MAX
0.02 NOM
0.30
0.23
0.18
SEATING
PLANE
0.20 REF
COPLANARITY
0.08
COMPLIANT TO JEDEC STANDARDS MO-220-VJJD-2
Figure 12. 40-Lead Lead Frame Chip Scale Package [LFCSP_VQ]
6 mm × 6 mm Body, Very Thin Quad
(CP-40)
Dimensions shown in millimeters
ORDERING GUIDE
Model
Temperature Range
Package Description
Package Option
Ordering Qty
ADP3196JCPZ-RL1
0°C to 85°C
40-Lead Lead Frame Chip Scale Package [LFCSP_VQ]
CP-40
2,500
1
Z= Pb-free part.
are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any
ON Semiconductor and
products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising
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Rev. 1 | Page 18 of 18 | www.onsemi.com
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