|
|
PDF FAN7585 Data sheet ( Hoja de datos )
| Número de pieza | FAN7585 | |
| Descripción | Intelligent Voltage Mode PWM IC | |
| Fabricantes | Fairchild Semiconductor | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de FAN7585 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
|
No Preview Available !
FAN7585
Intelligent Voltage Mode PWM IC
www.fairchildsemi.com
Features
• Complete PWM Control and House Keeping Circuitry
• Few External Components
• Precision Voltage Reference Trimmed to 2%
• Dual Output for Push-Pull Operation
• Each Output TR for 200mA Sink Current
• Variable Duty Cycle by Dead Time Control
• Soft Start Capability by Using Dead Time Control
• Double Pulse Suppression Logic
• Over Voltage Protection for 3.3V/5V/12V
• Under Voltage Protection for 3.3V/5V/12V
• Over Current Protection for 3.3V/5V/12V
• One More External Input for Various Protection (PT)
• Remote On/Off Control Function (PS-ON)
• Latch Function Controlled by Remote and Protection
Input
• Power Good Signal Generator with Hysteresis
Typical Application
• PC Power Supply
24-SDIP
1
©2003 Fairchild Semiconductor Corporation
Description
The FAN7585 is a fixed frequency improved performance
pulse width modulation control circuit with complete house-
keeping circuitry for use in the secondary side of SMPS
(Switched Mode Power Supply). It contains various func-
tions, which are overvoltage protection, undervoltage protec-
tion, over current protection, remote on/off control, power
good signal generator, etc.
OVP (Over Voltage Protection) Section
It has OVP functions for +3.3V,+5V,+12V outputs and PT.
The circuit is made up of a comparator with four detecting
inputs and without hysteresis voltage. Especially, PT (Pin19)
is prepared for an extra OVP input or another protection
signal.
UVP (Under Voltage Protection) Section
It also has UVP functions for +3.3V, +5V, +12V outputs. The
block is made up of a comparator with three detecting inputs
and without hysteresis voltage.
OCP (Over Current Protection) Section
It has precision OCP functions for +3.3V, +5V, +12V out-
puts. The block is made up of three comparators with current
source setting function. Two inputs of each OCP comparator
are connected to both sides of current sensing inductor that is
located in the secondary output of SMPS.
Remote On/Off Section
The remote on/off section is used to control SMPS exter-
nally. If a high signal or open state is supplied to the remote
on/off input, PWM signal becomes a high state and all sec-
ondary outputs are grounded. The remote on/off signal is
transferred with some on-delay and off-delay time of 8ms,
24ms respectively.
Precision Reference Section
The reference voltage is trimmed to ±2%.
(4.9V ≤ Vref ≤ 5.1V)
PG (Power Good Signal Generator) Section
The power good signal generator is to monitor the voltage
level of power supply for safe operation of a microprocessor
having some delay time at turn-on. The power good output
should be low state before the output voltatge is out of regu-
lation at turn-off.
Rev. 1.0.0
1 page  
Absolute Maximum Ratings
Characteristics
Supply Voltage
Collector Output Voltage
Collector Output Current
Power Dissipation (FAN7585)
Operating Temperature Range
Storage Temperature Range
Symbol
VCC
VC1,VC2
IC1,IC2
PD
TOPR
TSTG
Temperature Characteristics
Characteristics
Temperature Coefficient of Vref (-25°C ≤ Ta ≤ 85°C)
Symbol
∆Vref/∆T
Value
40
40
200
1.5
-25 to 85
-65 to 150
Min.
-
Typ.
0.01
FAN7585
Unit
V
V
mA
W
°C
°C
Max.
-
Unit
%/°C
5
5 Page 
3. OCP Block
FAN7585
Sense Inductor
Equivalent Resistor(Rs) ≅ 5mΩ
Io
17
Roffset IS12
(Offset Voltage Resistor)
VS12
18
OVP Outpu t
VS5
16
COMP1
IrIeref1f × 5
(100uA)
IS5 15
VS33 14
COMP2
IrIeref1f ×× 5
(100uA)
IS33 13
COMP3
IrIeref1f ×× 5
(100uA)
Iref1=20µA at RI=62kΩ
TPROT
It also has OCP function for +3.3V,+5V,+12V outputs. The block is made up of three comparators. Pin17(IS12), pin15(IS5)
and pin13(IS33) are current sense inputs for +12V, +5V and +3.3V outputs respectively. These pins are connected to the cur-
rent sensing resistor or inductor.
Each OCP level is determined by RI resistor , so you can define over current protection level by changing RI resistor. Pin8(RI)
voltage is always 1.25V, so if you connect 62kΩ resistor, the reference current is 20uA(Iref1).
If the voltage drop of the sense resistor or inductor is larger than offset voltage (Voffset = Roffset × 5 × Iref1), the DTC becomes
"High" after some delay(38ms at CTUVP=0.47uF)and the main SMPS is turned off. That means the output voltage(+3.3V,
+5V, +12V) will be ground level.
After main power is turned off at OCP and initialized by REM, if REM signal is changed from "High" to "Low", main power
becomes operational.
For example, if you want to define 5V output OCP level at 10A in the condition of equivalent resistor(Rs)= 5mΩ, you can
determine the offset voltage resistor(Roffset) as following method.
- Iref1 = 1.25V / 62kΩ = 20uA
- Voffset = RS × 5 × Iref1 = 5mΩ × 10A = 50mV
- Therefore, Roffset = 50mV / (5 × Iref1) = 500Ω
By the way, OCP output signal can be delayed by protection delay capacitor(CTUVP) and its delay time is decided by the value
of CTUVP.
Tuvp ≈ C-----T---U----V∆---P-I---*---∆----V-- = 0----.--4---7--2--u-1--F--u--*-A--1---.--7----V-- = 38msec
If you use too small (or large) capacitor, the charging time would decrease (or increase) very much and it can cause
malfunction at the transient time. So you have to choose the reasonable delay time for system optimization by changing the
external capacitor value.
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet FAN7585.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| FAN7585 | Intelligent Voltage Mode PWM IC | Fairchild Semiconductor |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |