BWTECH BW7385A Tm (transition mode) fixed on -time pfc control Datasheet

Preliminary BW7385A
High Power Factor & Accuracy Constant Current LED Driver
Features
Description
TM (Transition Mode) Fixed On -Time PFC
The BW7385A is a highly-integrated, low startup
Control
current, TM (Transition Mode), fixed on- time PFC
Accuracy Constant Current
control and PWM controller. These functions enable the
Low BOM Cost
LED driver to easily meet the accuracy average LED
Inductor Size Reduction
current and high power factor requirements. The
CT Pin Adjust Frequency Range for
integrated functions also include the LED short
Optimization
protection, over voltage protection, over load
Over Voltage Protection (OVP)-Auto Recovery
protection. The COMP pin controls the duty by
LED Short Protection (SCP) -Auto Recovery
connected an RC compensation network to ground
Over Load Protection (OLP) -Auto Recovery
and forming the closed loop feedback control.
SOT-26 Package
The BW7385A improves the performance and
Compatible Inductance Ballast
reduces the cost of the LED driver. It is a 6-pin
Incompatible Electronic Ballast
SOT-26 package.
Application
GU10 /E14 LED Bulb
Others LED Lighting Applications
1
Preliminary BW7385A
Pin Configuration
Pin Description
Pin No.
Name
Function
1
VCC
Power Supply Pin
2
GND
Ground Pin
3
DRV
4
CT
5
CS
6
COMP
The DRV pin is connected to the totem pole gate driver to drive the external power
switch.
The CT pin is connected to the current source to charge the external capacitor and
compare the COMP voltage to terminate the power switch.
Current Sense Pin
Feedback Compensation Network
Absolute Maximum Ratings
Supply Voltage VCC --------------------------------------------------------------------------------------------------------CT, COMP, CS ----------------------------------------------------------------------------------------------------
30V
-0.3V ~ 7V
DRV -------------------------------------------------------------------------------------------------------
15V
℃
Operating Ambient Temperature ------------------------------------------------------------------------------ -20℃ ~ 85℃
Storage Temperature Range ---------------------------------------------------------------------------------- -65℃ ~ 150 ℃
SOT-26 Package Thermal Resistance (junction to ambient) ----------------------------------------------- 250℃/W
Power Dissipation (SOT-26, at ambient temperature = 85℃) ------------------------------------------------ 250mW
Lead Temperature (All Pb free packages, soldering, 10 sec) -------------------------------------------------- 260℃
Junction Temperature ------------------------------------------------------------------------------------------------------- 150
ESD Voltage Protection, Human Body Model -------------------------------------------------------------------------ESD Voltage Protection, Machine Model
-----------------------------------------------------------------------------
2KV
200V
2
Preliminary BW7385A
Function Block
VCC
UVLO
Internal Bias & Vref
All Blocks
Vref OK
VCC OK
EN
VCCOVP
+
31.5 V
debounce
-
Protection
OCP
+
Current
Limit
-
COMP
CS
R
+
VREF
gm
On Time
Controller
-
Q
Driver
stage
OUT
R
S
CT
Sawtooth
Generator
STARTER
Current
Detector
GND
3
Preliminary BW7385A
Application Circuit
4
Preliminary BW7385A
Electrical Characteristics (VCC = 15.0V & TA = +25℃, unless otherwise specified.)
Parameter
Pin
Min.
Typ.
Max.
Unit
SUPPLY VOLTAGE
Startup Current (VCC=UVLO on - 1V)
1
10
50
uA
Operating Current (with 1nF load on OUT pin), Vcomp = 2.5V
1
2.5
3.2
mA
1
1.6
2.5
mA
Operating Current (with 1nF load on OUT pin), Protection
Tripped (OVP, SCP,)
UVLO(off)
1
5.5
6.5
7.5
V
UVLO(on)
1
14
15
16
V
OVP Level on VCC Pin
1
29.5
31.5
33.5
V
OVP De-Bounce Time
1
40
us
VOLTAGE FEEDBACK
Feedback Reference Voltage
6
0.195
0.200
0.205
V
Tran-Conductance
6
300
uS
Output Sink Current
6
300
uA
Output Source Current
6
60
uA
CURRENT SENSING
Input Over Voltage Protection
5
1.8
2.0
2.2
V
Open Loop Voltage, CS Pin Open
5
5
V
Leading-Edge Blanking Time
5
450
nS
Delay to Output
5
130
220
nS
Rising Time, Load Capacitance = 1000pF
3
280
500
nS
Falling Time, Load Capacitance = 1000pF
3
80
150
nS
VGATE-Clamp (VCC = 25V )
3
12.5
15
V
200
uA
GATE DRIVER OUTPUT
CT OUTPUT SECTION
CT Pin Current
4
160
180
5
Preliminary BW7385A
Application Information
threshold voltage 31.5V, the output gate driver circuit will
Start-up Current
The typical start-up current is around 10uA. Very low
start-up current allows the PWM controller to
increase the value of start-up resistor and then
reduce the power dissipation on it.
UVLO (Under Voltage Lockout)
A hysteresis UVLO comparator is implemented in
BW7385A, then the turn-on and turn-off thresholds
be shut down immediately to stop the switching of power
MOSFET. The VCC pin OVP function is an auto
recovery type protection. If the OVP condition happens,
the pulses will be stopped and never recovery unless the
VCC pin voltage is down to the UVLO off level. The
BW7385A is working in an auto-recovery mode as
shown in Fig.2.
level are fixed at 15V and 6.5V respectively. This
hysteresis shown in Fig.1 ensures that the start-up
capacitor will be adequate to supply the chip during
start-up. For quickly startup the LED driver, the
start-up resistor should be matched with the startup
capacitor. Due to the low UVLO on level, so the
turn-on delay time will also never greater than the
general PWM IC.
Fig. 2
Gate Clamp
Driver is clamped to 15V by an internal clamping
circuit.
Those
damages
usually
come
from
undesired over-voltage gate signals. Under the
Fig.1
conditions listed below, the gate output will turn off
immediately to protect the power circuit.
LEB (Leading-Edge Blanking)
Each time the power MOSFET is switched on, a
turn-on spike will inevitably occur at the sense
resistor. To avoid fault trigger, a 450ns leading-edge
blanking time is built in. Conventional RC filtering
can therefore be omitted. During this blanking
period, the current-limit comparator is disabled and
can not switch off the gate driver.
OVP (Over Voltage Protection) on VCC
To prevent the LED driver from being damaged,
the BW7385A is implemented an OVP function on
VCC. When the VCC voltage is higher than the
OVP
6
Preliminary BW7385A
Package Information
SOT-26
SOT-26
SYMBOL
MILLIMETERS
MIN.
INCHES
MAX.
A
MIN.
MAX.
1.45
0.057
A1
0.00
0.15
0.000
0.006
A2
0.90
1.30
0.035
0.051
b
0.30
0.50
0.012
0.020
c
0.08
0.22
0.003
0.009
D
2.70
3.10
0.106
0.122
E
2.60
3.00
0.102
0.118
E1
1.40
1.80
0.055
0.071
e
0.95 BSC
0.037 BSC
e1
1.90 BSC
0.075 BSC
L
θ
0.30
o
0
0.60
8
o
0.012
o
0
0.024
8
o
Note: 1. Followed from JEDEC TO-178 AB.
2. Dimension D and E1 do not include mold flash, protrusions or gate burrs. Mold flash, protrusions or
gate burrs shall not exceed 10 mil per side
7
Preliminary BW7385A
Carrier Tape & Reel Dimensions
SOT-26
Application
A
H
178.0±2.00
50 MIN.
P0
P1
P2
D0
D1
4.0±0.10
4.0±0.10
2.0±0.05
1.5+0.10
-0.00
1.0 MIN.
SOT-26
Application
SOT -26
T1
C
d
8.4+2.00 13.0+0.50 1.5 MIN.
-0.00
-0.20
D
W
E1
20.2 MIN. 8.0±0.30 1.75±0.10
T
A0
B0
F
3.5±0.05
K0
0.6+0.00
-0.40 3.20±0.20 3.10±0.20 1.50±0.20
Carrier Width
Cover Tape Width
Devices Per Reel
8
5.3
3000
(mm)
8
Preliminary BW7385A
Tape and Specification Reel
SOT 26
Direction of feed
9
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