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BD7682FJ-LB Schematic ( PDF Datasheet ) - ROHM Semiconductor

Teilenummer BD7682FJ-LB
Beschreibung Low Noise Quasi-Resonant Control DC/DC converter IC
Hersteller ROHM Semiconductor
Logo ROHM Semiconductor Logo 




Gesamt 30 Seiten
BD7682FJ-LB Datasheet, Funktion
Datasheet
Low Noise Quasi-Resonant Control
DC/DC converter IC for AC/DC Converter
BD7682FJ-LB BD7683FJ-LB BD7684FJ-LB BD7685FJ-LB
General Description
This is the product guarantees long time support in the
Industrial market.
BD768xFJ series is a Quasi-resonant controller type
DC/DC converters that provide an optimum system for
all products that include an electrical outlet.
Quasi-resonant operation enables soft switching and
helps to keep EMI low. Design with a high degree of
flexibility is achieved with switching MOSFETs and
current detection resistors as external devices.
The built-in brown out function monitors the input
voltage as part of system optimization. The burst mode
function reduces input power at low power.
BD768xFJ series include various protection functions,
such as a soft start function, burst function, per-cycle
over-current limiter function, overvoltage protection
function, overload protection function, and brown out
function.
BD768xFJ series include a gate-clamp circuit for
optimal driving SIC-MOSFET.
Features
Pin 8 : SOP-J8 Package
(6.00mm × 4.90mm : 1.27mm pitch <TYP>)
Quasi-resonant type (low EMI)
Frequency reduction mode
Low current consumption (19µA), during standby
Low current consumption when no load (burst
operation when light load)
Maximum frequency (120kHz)
CS Pin Leading-Edge Blanking
VCC UVLO (Under Voltage Drop Out protection)
VCC OVP (Over Voltage Protection)
Per-cycle over-current protection circuit
Soft start
ZT trigger mask function
Voltage protection function (brown out)
ZT OVP (Over Voltage Protection)
Gate-clamp circuit
Key Specifications
Operating Power Supply Voltage Range:
VCC 15.0V to 27.5V
Normal Operating Current:
0.80mA(Typ)
Burst Operating Current:
0.50mA(Typ)
Maximum Frequency:
120kHz(Typ)
Operating Temperature:
-40°C to +105°C
Package 4.90mm x 6.00mm x 1.65mm pitch 1.27mm
(Typ.) (Typ.)
(TYP.)
(TYP.)
SOP-J8
4.90mm x 6.00mm x 1.65mm
Lineup
BD7682FJ
BD7683FJ
BD7684FJ
BD7685FJ
FBOLP
AutoRestart
Latch
AutoRestart
Latch
VCCOVP
Latch
Latch
AutoRestart
AutoRestart
Applications
Industrial equipment, AC Adaptor, Household appliances
Typical Application Circuit
Product structureSilicon monolithic integrated circuit
.www.rohm.com
© 2015 ROHM Co., Ltd. All rights reserved.
TSZ2211114001
This product has no designed protection against radioactive rays
1/27
TSZ02201-0F1F0A200050-1-2
17.Apr.2015. Rev.001






BD7682FJ-LB Datasheet, Funktion
BD768xFJ-LB Series
Datasheet
(2) Brown Out function (B.O.)
BD768xFJ has a built-in brown out function. When the input VH value is low, the brown out function stops the
DC/DC operations (The IC itself continues to operate). An example is shown in Figure 2. The input voltage which
is resistance-divided is inputted to the BO pin. If the BO pin value exceeds VBO (1.0 V typ), the circuit detects as
normal state, and DCDC operations are started. There is a current hysteresis IBO in the circuit.
The current hysteresis flow is described below.
BO < VBO (1.0 V typ) (abnormal) IBO with sync
BOVBO (1.0 V typ) (normal status) IBO without sync
FUSE
Filter
Diode
Bridge
VH
RH
RL
1155µuAA
BO
BO
Comp.
+
1.00V
Controller
BD768x
Figure 2. Block Diagram of Brown Out Function
Example: RH and RL Setting
In the following example, VHON is the operation start VH voltage (L to H), and VHOFF is the operation stop VH voltage
(H to L).
IC operation start (OFF => ON)
(VHON-1.0) /RH = 1.0/RL +15*10e-6
IC operation stop (ON => OFF)
(VHOFF-1.0) /RH = 1.0/RL
Based on the above, RH and RL can be calculated as follows.
RH VHON VHOFF / 15 * 10e 6, RL 1.0 / VHOFF 1.0* RH
Example 1: When using 100 V AC (140 V DC)
When RH = 2350kand RL = 34k, VHON = 105.8V (-25%) and VHOFF = 70.8V (-51%)
Current consumption is 8.0mW for both RH and RL.
Example 2: When using 230V AC (322V DC)
RH = 5200k, RL = 42k
VHON = 202.8V (-37%), VHOFF = 124.8V (-62%)
Current consumption is 20.1 mW for both RH and RL.
www.rohm.com
© 2015 ROHM Co., Ltd. All rights reserved.
TSZ2211115001
6/27
TSZ02201-0F1F0A200050-1-2
17.Apr.2015. Rev.001

6 Page









BD7682FJ-LB pdf, datenblatt
BD768xFJ-LB Series
Datasheet
(d) Determination of OFF Width (Turn ON)
OFF width is controlled at the ZT pin.
When switching is OFF, the power stored in the coil is supplied to the secondary-side output capacitor.
When this power supply ends, there is no more current flowing to the secondary side, so the switching MOS
drain pin voltage drops.
Consequently, the voltage on the auxiliary coil side also drops.
A voltage that was resistance-divided from the ZT pin by RZT1 and RZT2 is applied. When this voltage level
drops to VZT1 (100 mV typ) or below, switching is turned ON by the ZT comparator. Since zero current status is
detected at the ZT pin, time constants are generated using CZT, RZT1, and RZT2.
Additionally, a ZT trigger mask function (described in section 4 (e)) and a ZT timeout function (described in
section 4 (f)) are built in.
(e) ZT Trigger Mask Function (Figure 10)
When switching is set ON / OFF, superposition of noise may occur at the ZT pin.
At this time, the ZT comparator is masked for the TZTMASK time to prevent ZT comparator operation errors.
Figure 10. ZT Trigger Mask Function
A: DC/DC OFF=>ON
B: DC/DC ON=>OFF
C: Noise occurs at ZT pin, and ZT comparator is not operated by TZTMASK.
D: Same as A
E: Same as B
F: Same as C
G: Same as A
www.rohm.com
© 2015 ROHM Co., Ltd. All rights reserved.
TSZ2211115001
12/27
TSZ02201-0F1F0A200050-1-2
17.Apr.2015. Rev.001

12 Page





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