Document
fitipower integrated technology lnc. Preliminary
FR9810
21V, 6A, 500KHz Synchronous PWM-Buck DC/DC Converter
Description
FR9810 is a high-efficiency synchronous mode step-down DC/DC converter that employs a special process technique to obtain very low RDS(ON) for the internal metal–oxide–semiconductor field-effect transistor (MOSFET), with operation voltage in a wide 4.75V to 21V input voltage range. The output current is over 6A, and the efficiency is over 90%. Controller circuit design by a particular current mode operation provides fast transient response and eases loop stabilization.
This product has a very low standby current less
than 1µA in shutdown mode. When the
pin
voltage is less than 0.4V, FR9810 will turn off the
switching voltage regulator function and enter the
standby mode. Fault protection includes current
protect mode over current protection (OCP), voltage
protect mode under voltage lockout protection
(UVLO), and internal thermal shutdown.
This high-efficiency current mode step-down “Green Power Converter” Fitipower offers the standard small-outline integrated chip (SOIC) package with an exposed pad.
Features
● Internal MOSFET RDS(ON) (high side/low side): 120mΩ/20mΩ typ.
● Operation voltage: 4.75V to 21V ● Continuous output current support: 6A ● Feedback voltage: 0.805V ● High efficiency (up to 90%) ● Oscillation frequency (typical): 500 KHz ● Sync to external clock from 300 KHz to 800 KHz ● Internal compensation ● OCP/UVLO protection ● Over Temperature Protection (OTP) with hiccup
mode ● < 1µA shutdown current ● Thermal Enhanced SOP-8(Exposed Pad)
Package ● RoHS Compliant
Applications
● Networking equipment ● OLPC, Netbooks ● Distributed power systems ● LCD monitors/TVs/STBs ● External HDDs ● Security Systems
Pin Assignments
SP Package (SOP- 8 Exposed pad )
Ordering Information
FR9810□□□
TR: Tape / Reel
G: Green
Package Type SP: SOP-8(Exposed Pad)
Figure 1. Pin Assignment of FR9810
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fitipower integrated technology lnc. Preliminary
Typical Application Circuit
FR9810
VIN 4.75V to 18V
C4 0.1uF
R3 100KΩ
5 SHDN/S
1 VIN
4 BOOST
LX 2,3
C1 22uF/25V CERAMIC
C3 0.1uF
FR9810
7 VCC
FB 6
GND 8
L1 1.8uH
R1 4.99KΩ/1%
R2 10KΩ/1%
VOUT 1.2V
C2 47uF/6.3V CERAMIC
Figure 2. Output 1.2V Application Circuit
Figure 3. High Input Voltage Application Circuit
FR9810-Preliminary 0.1-FEB-2011
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fitipower integrated technology lnc. Preliminary
FR9810
Functional Pin Description
I/O
Pin Name
Pin No.
Pin Function
I
FB
6
Voltage Feedback Input Pin. FB and VOUT are connected using a resistive voltage divider. This IC senses feedback voltage via FB and regulates it at 805mV.
I
VIN
1
Power Supply Input Pin. Drive 4.75V to 21V voltage to this pin to power on this chip. A 22µF ceramic bypass capacitor is connected between VIN and GND to eliminate noise.
O
VCC
7 Bias Supply Output Pin. A 0.1µF capacitor must be connected from this pin to GND.
This pin provides a digital control to turn the converter on or off. For automatic start-up,
I
5 connect the
pin to VIN pin with a 100K ohm resistor. An external clock from
300KHz to 800 KHz can be applied to the
pin to change oscillation frequency.
O
LX
2,3
Power Switching Output Pin. This is the output pin that internal high-side NMOS switches to supply power.
O
BOOST
4
High-Side Gate-Drive Boost Input. A 0.1µF capacitor is connected from this pin to LX. It can boost the gate drive to fully turn on the internal high-side NMOS.
I
GND
8 Ground Pin. This pin is connected to the exposed pad with copper.
I Exposed Pad
Ground Pin. The exposed pad must be soldered to a large PCB area and connected to GND for maximum power dissipation.
Block Diagram
Figure 4. Block Diagram of FR9810
FR9810-Preliminary 0.1-FEB-2011
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fitipower integrated technology lnc. Preliminary
FR9810
Absolute Maximum Ratings
● Input Supply Voltage VIN--------------------------------------------------------------------------------- -0.3V to +22V ● LX Voltage VLX------------------------------------------------------------------------------------------- -0.3V to VIN +1V ● Boost Voltage VBS ---------------------------------------------------------------------------------------- VLX -0.3V to VLX +6V ● All Other Pins Voltage ---------------------------------------------------------------------------------- -0.3V to +6V ● Maximum Junction Temperature (TJ)----------------------------------------------------------------- +150℃ ● Storage Temperature (TS)------------------------------------------------------------------------------- -65℃ to +150℃ ● Lead Temperature (Soldering, 10sec.) -------------------------------------------------------------- +260°C ● Power Dissipation @TA=25℃, (PD)
SOP-8 (Exposed Pad )---------------------------------------------------------------------- 1.25W ● Package Thermal Resistance, (θJA):
SOP-8 Exposed Pad------------------------------------------------------------------------- 50°C/W ● Packa.