BP232XAJ
Application Guide
BP232XAJ & BP2325A
Replacement Guide
Contents
 Typical Design
 Operation Principle
 Calculation Tool
 Design Guide
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Typical Design
Package
BV/V
Rds(on)/Ω
BP2325AJ
SOP8
550
5
BP2326AJ
SOP8
500
2.3
BP2327AJ
SOP8
650
4.5
BP2328AJ
SOP8
600
1.8
BP2329AJ
SOT23-6
/
/
BP2328DJ
DIP8
650
2.3
 FB add 100pF with chip optimized to enhance the anti-jamming capability ；
 BP2329AJ is controller; external drive MOS, can push more power.
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Operation
 BP232XAJ series features：
1、Utilizes floating ground buck structure
2、Constant Ton to achieve high power factor
3、critical conduction mode operation
4、The average current sampling
5、Internal LED open protection/short protection
6、Internal Thermal Regulation Function
BP232XAJ
5 DRAIN
FB
4
6 DRAIN
CS
8
3 VCC
CS
7
1 COMP
GND 2
AC
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Operation
Swithing waveform
amplification
Current waveform
amplification
Swithing waveform
Current waveform
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Operation
 Constant Ton PFC control with line compensation
 Operates in Critical Conduction Mode, the inductor
current is sensed during the whole switching cycle
and limited cycle by cycle.
TO BULK structure：
High Vbus
Low Vbus
COMP
(Vin  Vout ) * Ton  L * Ipk
RAMP
Within a frequency cycle, ， constant Ton, Ipk
will follow Vin, to achieve PF correction.
1.5V
CS_OFF
ON
FB
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Suggestion for Design Tool
 key parmeters
The minimum system working frequency: suggested that selection in the 40~50KHz
（ Lowest operating frequency appears in full the minimum input voltage at peak ）, The
operating frequency is too high PF value will deteriorate, low operating frequencies will
require greater or more of the transformer primary side of the transformer to ensure that the
number of turns of unsaturated to ensure at the minimum input voltage do not exceed the
maximum on-time 24uS。
Fsw_min: >40kHz, Ton_max<24us @ Vin_min
The maximum magnetic flux density: suggested that selection <0.3T， Because the
system will reach the maximum peak current at the lowest input voltage peaks and, in some
extreme applications can increase the Bm, get a better price
Bmax<0.3T
 Over Temperature Protection
BP232XAJ version BP232XA version based on the current temperature curve VS
improvement, BP232XAJ slow decline in the current version when entering the temperature
setpoint, the improved version into the regulator when BP232XA flash point of the
phenomenon
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Design considerations
COMP Pin Design
 Put C_comp close to the COMP Pin and short trace in layout.
 Typical value for C_COMP is 1uF to geting better startup.
Typical operating temperature range is -55℃ to 125℃.
COMP impact on the startup time and PF loop.
Sink current on COMP lead to VCC restart at beginning of startup，but
compensate at buffer of increasing VCC Capactior.
To LTHD requested ，one more option is to use RC compensation on phase of
line voltage in control loop.
Design considerations
VCC Pin Design
 Startup Resistor and C_Vcc
Typical value 330K*2 in 1206 package
C_Vcc is typical 2.2uF/25V.
Typical operating temperature range is -55℃ to 125℃.
 Auxiliary Supply for Vcc, it need a HV fast recovery diode and current limit
resistor(ES1J).
The resistor value depends on the Vout and mains application.
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Design considerations
FB Pin parameters design(Important!)
 R_L for FB is typical 3K to avoid interruptions;
 Set V_FB about 1V during normal operation，keep margin for OVP and
Vo_min(FB OVP threshold is 1.7V).
 R_H could stand with BV voltage as result of two 1206 package.
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Design considerations
FB Pin Considerations Design(Important!)


Add 100pF on FB pin to avoid interruption .
Invite internal optimization to immune layout interruption.
Reason This paragraph is BP2325A false triggering,
BP2325AJ FB after the revision changes the new
algorithms to prevent false triggering OVP
FB_mask 1.1us
200pf
100pf
OVP_Threshold
无电容
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Design considerations
FB Pin Layout design(Put all three resistors close to the FB pin.)
 FB upper arm connection foil between the two resistors must be short,
FB node between the two resistors and down close to the chip FB Pin best foot,
The point takes away from the switching node, to prevent interference,
Next resistance FB preferably as short as possible cable to the ground.
CS Pin design(short current loop in trace and close IC_GND)
 CS connection GND Pin too long to be as short as possible resistance line,
connected to the IC output will lead to deterioration of the current regulation.
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Design considerations
Drain/GND Pin Design
 Copper area of Drain give clearance space under Pin7. Too much copper on
Drain weak the EMI but helpful a lot on thermal dissipation.
 In PCB Library, the package for SOP8 should at least remove Pin7, better as
well as Pin6 to extend the safety space.
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BP232XAJ & BP2325
Replacement Guide
Replacement
After Replacement
 same line regulation and load regulation
Full load line regulation
output current（mA）
160.0
155.0
150.0
BP2325AJ-Current average
145.0
140.0
135.0
BP2325A-Current average
130.0
125.0
120.0
85
115
145
175
205
input voltage（V）
15
235
265
Replacement
After Replacement
 same line regulation and load regulation
220Vac Load Regulation
90Vac Load Regulation
output current（mA）
output current（mA）
160.0
160.0
155.0
155.0
BP2325AJCurrent
average
150.0
145.0
BP2325AJCurrent average
150.0
145.0
140.0
140.0
BP2325ACurrent
average
135.0
130.0
BP2325ACurrent average
135.0
130.0
125.0
125.0
120.0
120.0
30
32
34
36
38
40
42
44
46
48
30 32 34 36 38 40 42 44 46 48 50
50
output voltage（V）
output voltage（V）
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Replacement
After Replacement
 same system performance on Efficiency, PF and THD
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Replacement
After Replacement

Over Temperature Protection
BP232XAJ version A version based on the current temperature curve VS
improvement, AJ slow decline in the current version when entering the temperature
setpoint, the improved version when entering the adjustment points A flash
phenomenon.
Output Current VS IC Temperature
output current（mA）
180
160
140
BP2325A-1#
Vin=265Vac
120
100
80
60
BP2325AJ-2#
Vin=265Vac
40
20
0
75.00
85.00
95.00
105.00
115.00
125.00
135.00
145.00
155.00
165.00
IC Temperature（℃）
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Replacement
Replacement considerations
 OVP
Compare with BP232XA, OVP of the BP232XAJ version is high than 6%.
R FBL
1.7V

R FBL  R FBH
VOVP
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Replacement
Replacement considerations
 Vo_min
The minimum load voltage depends on the ratio B divider resistors,
FB voltage setting impact on the min. output voltage, otherwise difficult to FB zero
crossing detection. increasing the proportion of FB up and down resistance could
improve it.
VCC
3
UVLO
&VREF
Thermal
Regulation
5,6 DRAIN
GND
2
COMP
1
PFC
Control
Logic &
Protection
Gm
+
VREF
Driver
Current
Sense
7,8 CS
ZCD
Demag
4
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FB
Q
S
Qb
R
+
CS_OFF
FB
0.35V/0.2V
Replacement
Replacement considerations
 Same EMI performance
EMI test the effect of consistent BP232XAJ and BP232XA performance on
assessment Demo.
 Surge
For surge capacity, different application requirements to test . The same
number of MOS consistent with the main lightning resistance.
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