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PDF FAN6861 Data sheet ( Hoja de datos )
| Número de pieza | FAN6861 | |
| Descripción | Green-Mode PWM Controller | |
| Fabricantes | Fairchild Semiconductor | |
| Logotipo |  |
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May 2009
FAN6861
Low-Cost, Highly Integrated, Green-Mode PWM
Controller for Peak Power Management
Features
Low Startup Current: 15µA Maximum
Green-Mode and Burst-Mode Operation for Low
Standby Power Consumption
Internal Soft Start: 10ms
Frequency Hopping for EMI Reduction
Peak-Current Mode Control with Cycle-by-Cycle
Current Limiting
Constant Output Power Limit (Full AC Input Range)
Built-in Slope Compensation
Two-Level Over-Current Protection (OCP) with
Delayed Shutdown (780ms) for Peak Power
Management
Open-Loop / Over-Load Protection (OLP)
VDD Over-Voltage Protection (OVP)
Programmable Over-Temperature Protection (OTP)
www.DataShAeept4pUl.iccomations
Switched Mode Power Supply (SMPS) with Motor
Load; such as for printer, scanner, motor drivers,
etc.
AC/DC Adapters
Open-Frame SMPS
Description
Highly integrated PWM controller, FAN6861 is
optimized for applications with motor load; such as
printer and scanner, which inherently impose some kind
of overload condition on the power supply during
acceleration mode. The two-level OCP function allows
the SMPS to stably deliver peak power during the motor
acceleration mode without causing premature shutdown
and while protecting the SMPS from overload condition.
The green-mode and burst-mode functions with a low
operating current (2.2mA maximum in green mode)
maximize the light load efficiency so that the power
supply can meet most stringent standby power
regulations.
The frequency-hopping function helps reduce electro-
magnetic interference (EMI) of a power supply by
spreading the energy over a wider frequency range.
The constant power limit function; minimizes the
components stress in abnormal condition and helps
designer to optimize the power stage more easily.
Many protection functions such; as OCP, OLP, OVP
and OTP, are fully integrated into FAN6861, which
improves the SMPS reliability without increasing the
system cost.
Ordering Information
Part Number
FAN6861TY
Operating Temperature Range
-40 to +105°C
Eco Status
Green
Package
SSOT-6
Packing Method
Tape & Reel
For Fairchild’s definition of Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
© 2009 Fairchild Semiconductor Corporation
FAN6861 • Rev. 1.0.1
www.fairchildsemi.com
1 page  
Electrical Characteristics
VDD = 15V and TA = 25°C, unless otherwise noted.
Symbol
Parameter
VDD Section
VDD-OP
VDD-ON
VDD-OFF
VDD-SCP
VDD-OVP
VDD-LH
IDD-ST
Continuously Operating Voltage
Turn-On Threshold Voltage
Turn-Off Voltage
Threshold Voltage for Output Short-Circuit
Protection (SCP)
VDD Over-Voltage Protection (Latch-Off)
Threshold Voltage for Latch-Off Release
Startup Current
IDD-OP
Normal Operating Supply Current
IDD-BM
Green-Mode Operating Supply Current
VDD-OVP
tD-VDDOVP
IDD-LH
VDD Over-Voltage Protection (Latch-Off)
VDD OVP Debounce Time
Latch-Off Holding Current
Feedback Input Section
AV
ZFB
VFBO
VFB-OLP
tD-OLP
tD-SCP
Input Voltage to Current Sense Attenuation
Input Impedance
FB Pin Open Voltage
Threshold Voltage for Open-loop Protection
Open-Loop Protection Delay Time
Short-Circuit Protection Delay Time
Current Sense Section
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tLEB
VSTHFL
VSTHVA
VOCP
VSLOPE
tSS
tD-OCP
Delay to Output
Leading-Edge Blanking Time
Flat Threshold Voltage for Current Limit
Valley Threshold Voltage for Current Limit
OCP Trigger Level
Slope Compensation
Soft-Start Time
FB Pin Protection Delay Time for Peak
Loading
Test Condition Min. Typ. Max. Unit
VTH-ON – 0.16V
With 1nF Load on
Gate, VFB ≥ VFB-N
GATE Open,
VFB = VFB-G
VDD = 5V
24
16.5 17.5 18.5
8.5 9.5 10.5
VDD-OFF VDD-OFF VDD-OFF
+0.5 +1.0 +1.5
24 25 26
345
8 15
V
V
V
V
V
V
µA
3 4 mA
2.2 mA
24 25 26 V
100 170 240 µs
25 40 55 µA
At Green Mode
1/4.5
14
5.0
4.3
700
20
1/4.0
16
5.2
4.6
780
25
1/3.5
18
5.4
4.9
860
30
V/V
kΩ
V
V
ms
ms
Duty > 51%
Duty = 0%
Duty = DCYMAX
100 250 ns
270 360
ns
0.85 0.89 0.93 V
0.65 0.70 0.75 V
0.47 0.50 0.53 V
0.30 0.33 0.36 V
7.5 10.0 12.5 ms
700 780 860 ms
Continued on following page…
© 2009 Fairchild Semiconductor Corporation
FAN6861 • Rev. 1.0.1
5
www.fairchildsemi.com
5 Page 
Protections
Self-protective functions include VDD Over-Voltage
Protection (OVP), Open-Loop/Overload Protection
(OLP), Over-Current Protection (OCP), Over-
Temperature Protection (OTP). Among them, OLP,
OCP, and SCP are auto-restart mode protections; while
OVP and OTP are latch-mode protections.
Auto-Restart Mode Protection: Once a fault condition
is detected, switching is terminated and the MOSFET
remains off. This causes VDD to fall because no more
power is delivered from auxiliary winding. When VDD
falls to VDD-OFF (9.5V), the protection is reset and the
operating current reduces to startup current, which
causes VDD to rise. FAN6861 resumes normal operation
when VDD reaches VDD-ON (17.5V). In this manner, the
auto-restart can alternately enable and disable the
switching of the MOSFET until the fault condition is
eliminated (see Figure 21).
Latch-Mode Protection: Once this protection is
triggered, switching is terminated and the MOSFET
remains off. The latch is reset only when VDD is
discharged below 4V by unplugging AC power line.
Vds
Power
On
Protection Triggers
Fault Removed
VDD
17.5V
9.5V
Operating Current
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3mA
acceleration mode. Therefore, the protection circuit
should be triggered after a specified time to determine
whether it is a transient situation or an abnormal
situation.
Figure 22. Two-Level OCP Operation
Open-Loop / Over-Load Protection (OLP)
When the upper branch of the voltage divider for the
shunt regulator (KA431 shown) is broken, as shown in
Figure 23, there is no current flowing through the opto-
coupler transistor, which pulls up the feedback voltage
to 5.2V.
When the feedback voltage is above 4.6V longer than
780ms, OLP is triggered. This protection is also
triggered when the SMPS output drops below the
nominal value longer than 780ms due to the overload
condition.
8uA
Normal
Operation
Fault
Situation
Normal
Operation
Figure 21. Auto Restart Operation
Two-Level Over-Current Protection (OCP)
FAN6861 has two levels of over-current protection
thresholds. One is for pulse-by-pulse current limit,
which turns off MOSFET for the remainder of the
switching cycle when the sensing voltage of MOSFET
drain current reaches the threshold. The other threshold
is for the over-current protection, which shuts down the
MOSFET gate when the sensing voltage of MOSFET
drain current is above the threshold longer than the
shutdown delay time (780ms).
This two-level OCP protection is designed for
applications with peak load characteristics, such as
printers and scanners.
These applications have motor load and inherently
impose over-load condition on the power supply during
© 2009 Fairchild Semiconductor Corporation
FAN6861 • Rev. 1.0.1
11
VFB
5.2V
VFB-OLP (4.6V)
OLP Shutdown Delay Time
OLP Triggers
Figure 23. OLP Operation
www.fairchildsemi.com
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet FAN6861.PDF ] | |
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