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Электронный компонент: FAN5063

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REV. 1.0.0 12/4/00
www.fairchildsemi.com
Features
Implements ACPI control with PWROK, SLP_S3 and
SLP_S5
Switch and linear regulator controller for 3.3V Dual (PCI)
Linear regulator controller and linear regulator for VADJ
Dual output adjustable from 2.5V to 3.5V
Break-before-Make
Drives all N-Channel MOSFETs plus NPN
Latched overcurrent protection for outputs
Power-up softstarts for the linear regulators
UVLO guarantees correct operation for all conditions
16 pin SOIC package
Applications
Camino Platform ACPI Controller
Whitney Platform ACPI Controller
Tehama Platform ACPI Controller
Description
The FAN5063 is an ACPI Switch Controller for the Camino,
Whitney and Tehama Platforms. It is controlled by PWROK,
SLP_S3 and SLP_S5, and provides 3.3V Dual for PCI and
VADJ Dual output for SDRAM or RAMBUS with 200mA
minimum base current for an external NPN transistor. An on-
board precision low TC reference achieves tight tolerance volt-
age regulation without expensive external components. The
FAN5063 also offers integrated Current Limiting that protects
each output, and softstart for the linear regulators. The
FAN5063 is available in a 16 pin SOIC.
Block Diagram
+3.3V Main
+5V Standby
+3.3V Dual (PCI)
4
5
6
+12V
16
-
+
REF
Over Current
+5V Standby
PWR_OK
SLP_S3
9
7
3
2
1
11
14
13
Softstart
10
+5V Main
VADJ Dual
(2.5V RAMBUS
or 3.3V SDRAM)
REF
15
12
8
SLP_S5
REF
Osc
-
+
-
+
-
+
FAN5063
ACPI Dual Switch Controller
FAN5063
PRODUCT SPECIFICATION
2
REV. 1.0.0 12/4/00
Pin Assignments
Pin Definitions
Pin Number
Pin Name
Pin Function Description
1
QCAP
Charge pump cap.
Attach flying capacitor between this pin and PUMP to
generate high voltage from standby power.
2
PUMP
Charge pump switcher.
3
5VSTBY
5V Standby.
Apply +5V standby on this pin to run the circuit in standby mode.
4
3VOUT1
3.3V main gate control.
Attach this pin to a transistor powering 3.3V dual from
the 3.3V main supply.
5
3VOUT2
3.3V standby gate control.
Attach this pin to a transistor powering 3.3V dual
from the 5V standby supply.
6
3VFB
3.3V voltage Feedback.
Pin 6 is used as the input for the voltage feedback
control loop for 3.3V dual.
7
SLP_S3
SLP_S3.
Control signal governing the Soft Off state S3. Internal current source
pulls this line high if left open.
8
SLP_S5
SLP_S5.
Control signal governing the Soft Off state S5. Internal current source
pulls this line high if left open.
9
PWR_OK
PWR_OK.
Control signal for switches. Internal current source pulls this line high if
left open.
10
SS
Softstart.
Attach a capacitor to this pin to determine the softstart rate.
11
GND
Ground.
Connect this pin to ground.
12
VADJFB
Adjustable Dual Voltage Feedback.
Pin 12 is used as the input for the voltage
feedback loop for the adjustable dual voltage.
13
VADJ
Adjustable Dual Voltage
. Pin 13 sources VADJ during standby.
14
VADJOUT
Adjustable Dual Voltage Base Control.
Attach this pin to an NPN transistor
powering VADJ from the 5V Main.
15
5VMAIN
5V Main.
Apply +5V Main on this pin to run the VADJ base drive.
16
VCCP
Main Power.
Apply +12V through a diode on this pin to run the circuit in normal
mode. Bypass with a 0.1F capacitor. When 12V is not present, this pin produces
voltage doubled 5V standby.
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
FAN5063
QCAP
PUMP
5VSTBY
3VOUT1
3VOUT2
3VFB
SLP_S3
SLP_S5
VCCP
5VMAIN
VADJOUT
VADJ
VADJFB
GND
SS
PWR_OK
PRODUCT SPECIFICATION
FAN5063
REV. 1.0.0 12/4/00
3
Absolute Maximum Ratings
Recommended Operating Conditions
V
CCP
15V
All Other Pins
13.5V
Junction Temperature, T
J
150C
Storage Temperature
-65 to 150C
Lead Soldering Temperature, 10 seconds
300C
Thermal Resistance Junction to Ambient
JA
85C/W
Thermal Resistance Junction-to-case,
JC
24C/W
Parameter
Conditions
Min.
Typ.
Max.
Units
+3.3VMAIN
3.135
3.3
3.465
V
+5VMAIN
4.75
5
5.25
V
+5VSTBY
4.75
5
5.25
V
+12V
11.4
12
12.6
V
Ambient Operating Temperature
0
70
C
FAN5063
PRODUCT SPECIFICATION
4
REV. 1.0.0 12/4/00
Note:
1. Voltage Regulation includes Initial Voltage Setpoint and Output Temperature Drift.
Electrical Specifications
(V
+5VSTBY
= V
+5VMAIN
=5V, V
+3.3V
= 3.3V, V+12V = 12V and T
A
= +25C using circuit in Figure 4, unless otherwise noted.)
The denotes specifications which apply over the full operating temperature range.
Parameter
Conditions
Min.
Typ.
Max.
Units
+3.3V DUAL
V
Out1
, On
10
V
V
Out1
, Off
I = 10A
200
mV
V
Out2
, On
Standby
5
mA
Total Output Voltage Variation
1
3VOUT2 On
3.135
3.3
3.465
V
Maximum Drive Current
3VOUT1 On
100
mA
Minimum Load Current
3VOUT2 On
50
mA
Overcurrent Limit: Undervoltage
80
%Vout
Overcurrent Delay Time
150
sec
Output Driver Deadtime
See Figure 2: Main
Standby
2
6
sec
: Standby
Main
200
1000
nsec
VADJ DUAL
I
B
V
O
> 3.3V
100
mA
V
O
3.3V
150
mA
Total Voltage Variation
1
R
1
= R
2
= 10K
2.375
2.5
2.625
V
Vadj Output Voltage Range
1.25
3.5
V
Overcurrent Limit
80
%Vref
Overcurrent Delay Time
150
sec
Output Driver Overlap Time
See Figure 2
1
5
sec
Common Functions
Charge Pump Frequency
250
KHz
+5VSTBY UVLO
4.5
V
+5VSTBY UVLO Hysteresis
0.5
V
+12V UVLO
7.5
V
+12V UVLO Hysteresis
800
mV
+5VSTBY Current
MAIN Power Present
10
25
mA
+12V Current
2.5
10
mA
Input Logic HIGH
2.0
V
Input Logic LOW
0.8
V
Softstart Current
6
A
Control Line Input Current
SLP_S5, SLP_S3, PWROK
100
A
Over Temperature Shutdown
150
C
PRODUCT SPECIFICATION
FAN5063
REV. 1.0.0 12/4/00
5
Table 1. Power Descriptors
*When PWROK =
SLP_S3
= 0 and
SLP_S5
transitions from 0 to 1, the FAN5063 remains in the S5 state. See Table 2.
Figure 1. Power State Usage Diagram
PWROK SLP_S3
SLP_S5
Main
3.3V Dual
VADJ
State
Usage
1
1
1
ON
ON, Powered from MAIN
ON, Powered from MAIN
S0
S0
1
0
1
OFF
ON, Powered from
STANDBY
ON, Powered from
STANDBY
S3
S0
S3
0
0
1
OFF
ON, Powered from
STANDBY
ON, Powered from
STANDBY
S3
S3
0
1
1
OFF
ON, Powered from
STANDBY
ON, Powered from
STANDBY
S3
S3
S0
1
0
0
OFF
ON, Powered from
STANDBY
OFF
S5
S0
S5
0
0
0
OFF
ON, Powered from
STANDBY
OFF
S5
S5
0
1
0
OFF
ON, Powered from
STANDBY
OFF
S5
S5
S0
1
1
0
ON
ON, Powered from MAIN
OFF
S5
Not Used
0
0
0
1
OFF
ON, Powered from
STANDBY
OFF
S5*
*
111
101
S0
001
S3
100
010
000
110
Not
Used
S5
Blocked
011
FAN5063
PRODUCT SPECIFICATION
6
REV. 1.0.0 12/4/00
Table 2. State Transition Table
Notes:
1. Control Signal order: PWROK, SLP_S3, SLP_S5.
2. Dash (--) signifies that no state change takes place.
3. X signifies that the state transition is blocked, and the FAN5063 remains in the S5 state.
Figure 2. Deadtime and Overlap Time Measurements
Figure 3. Control Logic for Dual Voltages and Memory Voltages
000
001
010
011
100
101
110
111
000
--
x
-
x
--
x
--
S0
001
S5
--
S5
-
S5
--
S5
S0
010
--
x
-
x
--
x
--
S0
011
S5
--
S5
--
S5
--
S5
S0
100
--
x
--
x
--
x
--
S0
101
S5
--
S5
--
S5
--
S5
S0
110
--
x
--
x
--
x
--
S0
111
S5
S3
S5
S3
S5
S3
S5
--
t
DT
t
DT
OUTPUT 1
OUTPUT2
2V
2V
2V
2V
t
OT
t
OT
OUTPUT
OUTPUT2
2V
2V
2V
2V
SLP_S3#
PWROK
STBY
MAIN
DUAL
SLP_S3#
PWROK
STBY
MAIN
VADJ
SLP_S5#
Initial Control Signal
Initial Control Signal
PRODUCT SPECIFICATION
FAN5063
REV. 1.0.0 12/4/00
7
Application Circuits
Figure 4. ACPI Selector
Table 3. FAN5063 Application Bill of Materials
Reference
Manufacturer, Part #
Quantity
Description
Comments
C1-4
Various
4
100nF, 25V
Ceramic
C56
Various
2
220F, 6V
Tantalum, ESR ~ 0.1
R1
Various
1
*
*10K
for 2.5V, 16.5K
for 3.3V
R2
Various
1
10K
Resistor
D1
Fairchild
MBR0520L
1
20V, 1/2A Schottky
Q1
Fairchild
FDS4410DY
1
N-channel
MOSFET
R
ds,on
= 20m
@ V
gs
= 4.5V
Q2
Fairchild
NDS9956A
1
N-channel
MOSFET
R
ds,on
= 110m
@ V
gs
= 4.5V
Q3
Fairchild
TIP41A
1
NPN
V
CE
~0.4V @ I
C
= 2A, I
B
= 100mA
U1
Fairchild
FAN5063
1
ACPI Dual Switch
Controller
C3
Q3
C2
+12V
SLP_S5
SLP_S3
5V Main
3.3V Dual (PCI)
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
Adjustable Dual
Q1
+5V Standby
3.3V Main
Q2
C1
C5
C4
R1
R2
C6
D1
U1
FAN5063
PWR_OK
PRODUCT SPECIFICATION
FAN5063
REV. 1.0.0 12/4/00
8
Figure 5. Camino System Architectural Block Diagram (Power Paths Only)
5Vmain, 18A
5Vstdby 720mA
12V, 6A
Typedet
Linear
Linear
Linear/Switch
Linear
Conversion
Synchronous
Vcore 2V/17.4A
RC1587
RC5058
SO24
Linear
Linear
PWROK SLP_S3# SLP_S5#
FAN5063
SO16
Switch
2.5V RAMBUS @ 2A/144mA
or 3.3V SDRAM @ 4.8A/100mA
3.3Vdual 2.4A/500mA/500mA PCI
Vtt 1.5V/2A
Vck 2.5V/600mA
Vagp 3.3V/1.5V/2A
Vnb 1.8V/2A
3.3Vmain, 14A
ATX
FAN5063
PRODUCT SPECIFICATION
9
REV. 1.0.0 12/4/00
Application Information
The FAN5063 Controller
The FAN5063 is a fully compliant ACPI controller IC. Used
with an ATX power supply, it generates a 3.3V Dual for PCI,
and power for either SDRAM and RAMBUS, and has a large
array of additional protection functions integrated in. Used in
conjunction with Fairchild's RC5058, it provides control and
power functions necessary to implement a Camino or Whit-
ney motherboard. It can also be used to generate the dual
voltages necessary for a Tehama motherboard.
Overview of ACPI
The Advanced Configuration and Power Interface, or ACPI,
is a system for controlling the use of power in a computer. It
enables the computer manufacturer and the computer user to
determine the computer's power usage dynamically. For
example, when the computer has been unused for a certain
time, the monitor and peripherals could be turned off, and
their states saved to memory. After a longer period, the pro-
cessor could be turned off, and the memory saved to disk. A
peripheral could then re-awaken the entire system on the
occurrence of an event, such as the arrival of a FAX on a
modem.
As shown in Figure 5, the available power inputs to the com-
puter system from the ATX power supply are +5V main, +12V
main, +3.3V main, and +5V standby. "Main" means that
these power outputs are available under full-power operation
of the system, but can be turned off in some of the power-
saving modes. "Standby" means that this power output is
always present.
The most general ACPI system requires four dual outputs:
5V dual, 3.3V dual, 3.3V SDRAM, and 2.5V RAMBUS (or
2.5V dual). "Dual" means that the power can be (but is not
necessarily) present whether the main power supplies are
present or not. To ensure the presence of these outputs, while
not overloading the standby power, they have dual inputs,
from both main power and standby. The presence or absence
of the dual outputs is determined by the control signals to the
FAN5063.
ACPI States
As shown in Table 1, there are three ACPI states that are of
primary concern to the system designer, designated S0, S3
and S5. S0 is the full-power state, the state of the computer
when it is being actively used. The other two states are sleep
states, reflecting differing levels of power-down.
S3 is a state in which the processor is powered down, but its
last state is being preserved in IC memory, which is kept on.
Since memory is fast, the computer can quickly come back
up to full operation. However, this state continues to draw
moderate power, due to the memory being kept alive.
S5 is a state in which memory is off, and the last state of the
processor has been written to the hard disk. Since the disk is
slow, the computer takes longer to come back to full operation.
However, since memory is off, this state draws minimal
power.
It is anticipated that only the following state transitions will
occur: S0
S3, S0
S5, S3
S5, S5
S0, and S3
S0;
the transition S5
S3 will occur only as an intermediate state
during the transition from S5
S0. To prevent overcurrent
limit from activating, the FAN5063 blocks this transition.
For example, when PWROK = SLP_S3 = 0, and SLP_S5
transitions from 0 to 1, the FAN5063 remains in the S5 state.
See Table 2.
3.3V Dual Output
The 3.3V dual output is intended to power subsystems such
as the computer's PCI slots. A typical application that would
require the use of 3.3V dual rather than +3.3V main for a PCI
slot would be the use of a modem: if the system needs to be
able to awaken from sleep when the modem receives incom-
ing data, then that slot must be powered from dual, because
main power is off. Other slots not requiring dual power can
be configured using the control signals.
3.3V dual is generated by two MOSFETs, one from +3.3V
main, the other from +5V standby, as shown in Figure 4. When
main power is present, the MOSFET Q1 is turned on as a
switch, so that input and output are connected together. When
main power is absent, the MOSFET Q2 is controlled by the
FAN5063 as a linear regulator, generating a regulated 3.3V
from +5V standby. The MOSFET Q1 must be connected as
shown in the figures, to avoid back-feed.
The state of the MOSFETs is controlled by the SLP_S3 and
PWROK lines, as shown in Figure 3. When both SLP_S3 and
PWROK are asserted, the main switch is on, and the linear reg-
ulator is off. If either line is de-asserted, the main switch is
off and the linear regulator is on.
Q1 and Q2 as shown in Table 3 have different R
DS,on
ratings.
In a typical system, it is anticipated that full-power current
will be about 2.4A maximum, and standby current will be
about 500mA maximum. The difference in maximum cur-
rents means that Q2 can be a less expensive device than Q1.
The design of the linear regulator for the 3.3V Dual necessi-
tates a minimum load current of 50mA. Furthermore, in order
to guarantee stable operation, the output capacitor on the 3.3V
Dual must have a minimum ESR as shown in Figure 6. The
hatched region shows acceptable values of ESR vs. output
capacitance. Values of the output capacitor less than 47F or
greater than 300F are not recommended.
FAN5063
PRODUCT SPECIFICATION
10
REV. 1.0.0 12/4/00
Figure 6. Recommended C vs. ESR for
Stable Operation of the 3.3V Dual
Adjustable Dual Output
The adjustable dual output is intended to provide power to
RAMBUS or SDRAM memory.
Adjustable dual is generated by one external NPN bipolar
acting as a linear regulator from +5V main, and one linear
regulator internal to the FAN5063 from +5V standby, as
shown in Figure 4, and in the block diagram on the front
page. When main power is present, the NPN Q3 linear regu-
lates, and when main power is absent, the internal linear reg-
ulator is on. Q3 cannot be substituted with a MOSFET. If
used in one direction, the MOSFET's body diode would per-
mit back-feed; if used in the other direction, it would short-
circuit the linear regulator action.
The state of the external MOSFET and the internal linear
regulator is controlled by the SLP_S3 and PWROK lines,
and additionally the SLP_S5 line, as shown in Figure 3.
When SLP_S5 is de-asserted, both the external MOSFET
and the internal linear regulator are off, and there is no out-
put voltage on the 3.3V SDRAM line.
If the SLP_S5 line is asserted, the adjustable dual output is
on. In this condition, if either the SLP_S3 or the PWROK
line, or both, are de-asserted, the linear regulator is on and
the MOSFET is off. Only in the case if both the SLP_S3 and
the PWROK lines are asserted, the MOSFET is on and the
linear regulator is off.
In a typical system, it is anticipated that standby current will
be a maximum of 144mA, and full-power current may be as
high as 2A. This places some significant constraints on the
selection of Q3. Since its input may be as low as (5V 5%)
= 4.75V, there is only 4.75V 3.3V = 1.45mV of V
CE
head-
room for its operation as a linear regulator. For this reason
the FAN5063 can provide up to 200mA of steady-state base
current. The TIP41A device shown has a sufficiently low V
CE,
sat
to guarantee worst-case regulation even at 2A I
E
with this
base current.
The output voltage of the Adjustable Dual is set with two
resistors as shown in Figure 4, according to the equation.
FAN5063 ACPI Control Lines
As already discussed, the FAN5063 outputs are controlled
by the three ACPI control lines, SLP_S3, SLP_S5 and
PWROK, as summarized in Tables 1 and 2. System design-
ers must in particular be careful to ensure that their system is
designed with SLP_S5, not SLP_S5; if SLP_S5 is used, it
must be inverted before being used with the FAN5063.
The control lines have internal pull-ups of approximately
40A, and so can be controlled by open collector drivers if
desired. In a noisy system, it may be desirable to filter these
lines, which can be done with a 1K
resistor and a small
capacitor.
FAN5063 Dynamic Operation
The FAN5063 is designed to minimize the output capaci-
tance required to hold up the various output lines during
transitions between different states. Thus in particular, the
adjustable dual output has guaranteed minimum overlap
time, the time (as shown in Figure 2) during a state transition
during which both main and standby are connected to the
output. This overlap time guarantees that a power source is
always connected to the output, so that there will be no dip in
the output voltage during state transitions. There is also a
maximum overlap time, to ensure that the standby power
doesn't have to source main power very long, thus minimiz-
ing thermal stress on the standby device.
The 3.3V dual is different because it is powered by both a
linear regulator and a switch. If the linear regulator were to
turn on while the switch is on (or vice versa) the linear regu-
lator would supply power to the main line through the
switch. For this reason, the linear regulator must be off
before the switch is on, and vice versa. Thus, this output has
guaranteed minimum deadtime when both linear regulator
and switch are off. During this time, the output capacitor
must hold up the load, and so there is also a specified maxi-
mum deadtime, allowing a maximum necessary capacitance
to be selected, see below.
Stability
As with all linear regulators, the FAN5063's linear regulators
require a minimum load. With the exception of the 3.3V dual
output, however, all of these minimum loads are internal to
the FAN5063. The 3.3V dual output requires a minimum load
of 50mA; if a situation may occur in which the load is less than
50mA, additional steps may be necessary to ensure stability.
Furthermore, depending on location, it may be necessary to
bypass the drain (or collector) of the linear regulator with a
low ESR capacitor for stability. As a rule of thumb, if the
pass element is more than 1" from its power source, it should
have a bypass.
100
47
330
100
200
C (
F)
ESR (m
)
300
400
200
300
Vadj
1.25V
R
1
R
2
+
R
2
-------------------
=
PRODUCT SPECIFICATION
FAN5063
REV. 1.0.0 12/4/00
11
Softstart
Pin 10 of the FAN5063 functions as a softstart. When power
is first applied to the chip, a constant current is applied from
the pin into an external capacitor, linearly ramping up the
voltage. This ramp in turn controls the internal reference of
the FAN5063. providing a softstart for the linear regulators.
The actual state of the FAN5063 on power up will be deter-
mined by the state of its control lines.
The switches in the system must be either on or off, and so
softstart has no effect on their characteristics: if the appropri-
ate control signals are asserted, they will turn on at once.
The softstart is effective only during power on. During a
transition between states, such as from S5
S0, the linear
regulators are not softstarted.
It is important to note that the softstart pin is not an enable;
pulling it low will not necessarily turn off all outputs.
Charge Pump
In main power operation, the FAN5063 is run from the +12V
main supply. This supply also provides voltage to the various
MOSFET gates. However, during standby, this supply is off.
To provide power to the chip and the appropriate gates, the
FAN5063 incorporates a free-running charge pump. As
shown in Figure 4, and in the block diagram on the front
page, a capacitor attached between pins 1 and 2 of the
FAN5063 acts as a charge pump with internal diodes. The
charge pump output is internally diode or'red with the 12V
input. The 12V input must have a series diode to prevent
back-feeding the charge pump to the + 12V main when in
standby. The 12V input line needs a bypass capacitor for
high-frequency noise rejection.
Overcurrent
The FAN5063 does not directly detect current through the
devices that power its outputs. Instead, it monitors the output
voltages. In the event of a hard short, the voltage drops
below 80% of nominal, and all outputs are latched off, and
remain off until 5V standby power is recycled. The overcur-
rent latch off is delayed by 150sec to prevent nuisance trips.
During softstart, the overcurrent voltage monitors are kept
proportional to the reference, to avoid tripping overcurrent
during startup.
In the S5 state, when the memory outputs are off, the voltage
monitors on the memory lines are disabled, to prevent trip-
ping the overcurrent. When turning these lines back on from
the S5 state, overcurrent is prevented from tripping because
the S3 state is blocked. See Table 2.
If the adjustable dual is not used, its feedback line, pin 12,
must be connected to 5V STBY, to prevent an overcurrent
trip.
UVLO
If the +5V standby is below approximately 4.5V, the
FAN5063 will leave off or turn off all outputs. Similar com-
ments apply to the +12V main at 7.5V. The +5V standby
UVLO has approximately 0.5V hysteresis, the +12V main
UVLO 1V.
Over Temperature
The FAN5063 is capable of sourcing substantial current,
200mA minimum to the adjustable voltage transistor's base dur-
ing S0 and 144mA to the line during S3. As a result, there can
be heavy power dissipation in the IC. While the FAN5063 is
designed to accept this power dissipation, any overloading of
outputs can cause excessive heating. If the FAN5063 die
temperature exceeds about 150, all outputs are shut off.
Outputs remain off until the die temperature returns to its
safe area.
Transistor Selection
External transistor selection depends on usage, differing for
the linear regulators and the switches.
The MOSFET switches, should be sized based on regulation
requirements and power dissipation. Since the ATX outputs
are 5%, the outputs driven from them must be wider. As an
example, if we want to hold 3.3V PCI to -10%, we can drop
only 5% = 165mV across Q1. At 2.4A, this means Ql must
have a maximum R
DS,on
of 165mV/2.7A = 68m
, including
tolerance and self-heating effects. We thus choose a Fairchild
FDC633N, which has 72m
maximum R
DS, on
at 4.5V V
GS
at 25C. We can estimate power dissipation as (2.4A)
2
*
42m
= 270mW, which should be acceptable for this pack-
age.
Q2 is a MOSFET functioning as a linear regulator. Since it
delivers only 500mA, it is easy to select a MOSFET, it need
only be able to handle 500mA * (5V + 5% 3.3V) = 1W.
We select the Fairchild FDS6630A in an SO-8 package.
Q3 is an NPN bipolar functioning as a linear regulator. As
already discussed, it must have a V
CE,sat
lower than 1.45V at
I
E
= 2A and I
B
= 200mA. Its power dissipation can be as
high as (5V + 5%3.3V) * 2A = 3.9W.
FAN5063
PRODUCT SPECIFICATION
12
REV. 1.0.0 12/4/00
Alternate for Adjustable Dual
Instead of the bipolar transistor shown in Figure 4 for Q3, the
linear pass element for the adjustable dual, a MOSFET and
schottky diode can be used as shown in Figure 7.
Figure 7. Adjustable Dual with MOSFET
The schottky should be chosen to have a low V
f
at the speci-
fied adjustable voltage and current. The MOSFET's R
DS,on
must then be lower than (5V -5% -VADJ -V
f
)/I
Dual
including
temperature. An additional constraint is that the MOSFET
must have a gate threshold voltage lower than 1.5V. For exam-
ple, for 2.8A @3.3V, choose the diode to be an MBR835, and
the MOSFET a Fairchild FDC653M. This same technique
can then also be used for adjustable currents higher than can
be achieved with the bipolar transistor.
Output Capacitor Selection
Output capacitor selection depends on whether the line has
overlap time or not.
For both the adjustable dual, there is guaranteed overlap time
between when one source is turned on and the other source
turned off. For this output, the output capacitor is not needed
to hold up the supply, but only for noise filtering and to
respond to transient loading.
The 3.3V dual output has deadtime between when one
source is turned off and the other source turned on. During
the time when both are off, the output current must be sup-
plied by the output capacitor. Mitigating this, it must be real-
ized that the system will be designed in such a way that the
current has gone to its sleep value before the transition
occurs. For example, the 3.3V dual has a sleep current of
500mA maximum. Maximum deadtime is 6sec, and so
charge depletion is 500mA * 6sec = 3C. Suppose that we
have a total of 8% drop due to the source tolerance and the
MOSFET drop, and we are trying to hold 10% regulation.
The remaining 2% = 66mV implies a minimum capacitance
of 3C/66mV = 45F.
FAN5063
14
5V Main
Adjustable Dual
12
PRODUCT SPECIFICATION
FAN5063
REV. 1.0.0 12/4/00
13
Mechanical Dimensions
16 Lead SOIC
16
9
1
8
D
A
A1
C
ccc C
LEAD COPLANARITY
SEATING
PLANE
e
B
L
h x 45
C
E
H
A
.053
.069
1.35
1.75
Symbol
Inches
Min.
Max.
Min.
Max.
Millimeters
Notes
A1
.004
.010
0.10
0.25
.020
0.51
B
.013
0.33
C
.0075
.010
0.19
0.25
E
.150
.158
3.81
4.00
e
.228
.244
5.80
6.20
.010
.020
0.25
0.50
H
.050 BSC
1.27 BSC
h
L
.016
.050
0.40
1.27
0
8
0
8
3
6
5
2
2
N
16
16
ccc
.004
0.10
--
--
D
.386
.394
9.80
10.00
Notes:
1.
2.
3.
4.
5.
6.
Dimensioning and tolerancing per ANSI Y14.5M-1982.
"D" and "E" do not include mold flash. Mold flash or
protrusions shall not exceed .010 inch (0.25mm).
"L" is the length of terminal for soldering to a substrate.
Terminal numbers are shown for reference only.
"C" dimension does not include solder finish thickness.
Symbol "N" is the maximum number of terminals.
FAN5063
PRODUCT SPECIFICATION
12/4/00 0.0m 004
Stock#DS30005063
2000 Fairchild Semiconductor Corporation
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY
PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER
DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
LIFE SUPPORT POLICY
FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body,
or (b) support or sustain life, or (c) whose failure to perform
when properly used in accordance with instructions for use
provided in the labeling, can be reasonably expected to
result in significant injury to the user.
2. A critical component is any component of a life support
device or system whose failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
www.fairchildsemi.com
Ordering Information
Product Number
Package
FAN5063M
16 pin SOIC