OB2632
Adaptive Multi-Mode PWM Controller
GENERAL DESCRIPTION
FEATURES
OB2632 is a highly integrated current mode PWM
control IC with high voltage startup, optimized for
high
performance,
low
standby
power
consumption and wide output voltage range PD
adapter solutions, together with PD secondary
controller, such as OB2612. The controller is as
well compatible with cost effective offline flyback
converter applications covering a wide output
range.
At full loading, the IC operates in fixed frequency
mode. When the loading goes low, it operates in
Green mode with valley switching for high power
conversion efficiency. When the load is very small,
the IC operates in ‘Extended Burst Mode’ to
minimize the standby power loss. As a result, high
conversion efficiency can be achieved in the
whole loading range.
High voltage startup is implemented in OB2632CP,
which features with short startup time and low
standby power loss.
VCC low startup current and low operating current
contribute to a reliable power on startup and low
standby design with OB2632MP.
OB2632 offers complete protection coverage
including cycle-by-cycle current limiting (OCP),
over load protection (OLP), over temperature
protection (OTP), output short(SCP), output and
VDD over voltage protection.
Excellent EMI
performance is
achieved
with On-Bright
proprietary frequency shuffling technique.
The tone energy at below 23KHz is minimized to
avoid audio noise during operation.
OB2632 is offered in SOP8 or SOT23-6 package.
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nt
ia
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鑫
晨
■
o
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Multi-Mode Operation
o 125KHz max frequency mode @ Peak
Load
o 65KHz or 45KHz fixed frequency mode @
Full Load
o Valley switching operation @ Green mode
o Burst Mode @ Light Load & No Load
Adaptive loop gain compensation with Iovp
current detection
Ultra low operating current at light/no load
Internal OCP compensation for universal line
voltage
Extended burst mode control for improved
efficiency and low standby power
Power on soft start reducing MOSFET Vds
stress
Frequency shuffling for EMI
Audio noise free operation
High voltage startup integrating intelligent
brownout detection, AC off detection with XCAP discharge function(OB2632CP only)
Comprehensive protection coverage
o VDD under voltage lockout with hysteresis
(UVLO)
o Cycle-by-cycle over current protection
(OCP) with auto-recovery
o Overload protection (OLP) with autorecovery
o Over temperature protection (OTP) with
latch shut down
o VDD over voltage protection with latch
shut down
o Output over voltage protection with latch
shut down
o Output short protection (SCP) with autorecovery
o Brownout protection with auto-recovery
(OB2632CP only)
o Output diode short protection with autorecovery
Br
ig
ht
co
nf
id
e
■
APPLICATIONS
O
n-
Offline AC/DC flyback converter for
■ PD adapters
■ Wide output range adapters
©On-Bright Electronics
Confidential
1
Preliminary datasheet
OB_DOC_DS_263201
OB2632
Adaptive Multi-Mode PWM Controller
TYPICAL APPLICATION
VBUS
AC
Input
EMI
Filter
OPTO1-A
鸣
GPI
O
GAT
E
ISP
ISN
VDD
VDD
GND
VIN
PRT
VFB
OPTO
GATE
CS
鑫
晨
HV
GND
TYPE-C
OB2612
GND
CC
CC
o
FB
lt
OPTO1-B
OB2632MP Typical Application
O
n-
Br
ig
ht
co
nf
id
e
nt
ia
OB2632CP Typical Application
©On-Bright Electronics
Confidential
2
Preliminary datasheet
OB_DOC_DS_263201
OB2632
Adaptive Multi-Mode PWM Controller
GENERAL INFORMATION
Pin Configuration
The OB2632 is offered in SOP8 and SOT23-6
package, shown as below.
1
8
HV
FB
2
7
NC
CS
3
6
VDD
GND
4
5
GATE
GND
1
6
Gate
FB
2
5
VCC
PRT
3
4
CS
鸣
PRT
Package Dissipation Rating
Package
RJA(℃/W)
SOP8
90
SOT23-6
200
Recommended Operating Condition
Symbol Parameter
Range
VDD
VCC Supply Voltage
12 to 50V
Br
ig
ht
co
nf
id
e
nt
Ordering Information
Part Number
Description
OB2632CP
SOP8, Halogen-free, Tube
OB2632CPA
SOP8, Halogen-free, T&R
OB2632MP
SOT23-6, Halogen-free, T&R
ia
lt
o
鑫
晨
Absolute Maximum Ratings
Parameter
Value
VDD DC Supply Voltage
54V
High-Voltage Pin, HV
-0.3 to 500 V
(OB2632CP only)
FB Input Voltage
-0.3 to 7V
CS Input Voltage
-0.3 to 7V
PRT Input Voltage
-0.3 to 7V
Min/Max Operating
-40 to 150 ℃
Junction Temperature TJ
Operating Ambient
-40 to 85 ℃
Temperature TA
Min/Max Storage
-55 to 150 ℃
Temperature Tstg
Lead
Temperature
260 ℃
(Soldering, 10secs)
O
n-
Marking Information
©On-Bright Electronics
Confidential
3
Preliminary datasheet
OB_DOC_DS_263201
OB2632
Adaptive Multi-Mode PWM Controller
TERMINAL ASSIGNMENTS
I
2
FB
I
3
4
5
6
7
CS
GND
Gate
VDD
NC
I
P
O
P
8
HV
P
鑫
晨
PRT
Connected to the line input via resistors and diodes for startup and x-cap
discharge, this PIN allows the brownout detection as well.
I/O
Description
P
Ground
Feedback input pin. The PWM duty cycle is determined by voltage level
into this pin and the current-sense signal at CS pin
Multiple functions pin. Connecting a NTC resistor to ground for OTP
detection. Connecting a resistor from Vaux can adjust IOVP/ISCP
trigger current and detect transformer core demagnetization. If both
OTP and OVP/SCP are needed, a diode should be connected between
PRT pin and the NTC resistor.
Current sense input
Power Supply
Totem-pole gate driver output for power Mosfet
nt
For OB2632MP
Pin
Pin NO.
Name
1
GND
ia
lt
1
Description
Multiple functions pin. Connecting a NTC resistor to ground for OTP
detection. Connecting a resistor from Vaux can adjust IOVP/ISCP trigger
current and detect transformer core demagnetization. If both OTP and
OVP/SCP are needed, a diode should be connected between PRT pin
and the NTC resistor.
Feedback input pin. The PWM duty cycle is determined by voltage level
into this pin and the current-sense signal at CS pin
Current sense input
Ground
Totem-pole gate driver output for power Mosfet
Power Supply
鸣
I/O
o
For OB2632CP
Pin NO.
Pin Name
FB
I
3
PRT
I
4
5
6
CS
VDD
Gate
I
P
O
O
n-
Br
ig
ht
co
nf
id
e
2
©On-Bright Electronics
Confidential
4
Preliminary datasheet
OB_DOC_DS_263201
OB2632
Adaptive Multi-Mode PWM Controller
BLOCK DIAGRAM
HV(OB2632CP only)
Valley
Brown out
S
S
Brown out
Logic
Control
Q
GATE
Demag
鑫
晨
OVP
OLP
OCP
R
OVP
Soft Driver
鸣
HV
startup
CC loop
Gm
Internal
blocks
o
PWM comparator
PK/Green/
Burst
Temp
sense
EX OTP
OTP
OVP
id
e
OLP
Dio
CS
Diode
short
AVDD
FB
Adaptive Loop Gain
O
n-
Br
ig
ht
co
Iovp Detector
Timer
LEB
Valley
nf
Valley Detector
PK detect comparator
Vth_pk
OVTP
PRT
EX OVP
lt
SCP
Slope
compensation
OSC
nt
GND
Sample
ia
SCP
All prt
Dio
VDD
Vref&
Iref
AVDD
OVTP
UVLO
©On-Bright Electronics
Confidential
5
Preliminary datasheet
OB_DOC_DS_263201
OB2632
Adaptive Multi-Mode PWM Controller
ELECTRICAL CHARACTERISTICS
Normal Operation Current
Burst Operation Current
VDD Under Voltage Lockout
Enter
VDD Under Voltage Lockout
Exit (Recovery)
Pull-up PMOS active
UVLO(ON)
VDD=2V, HV=100V
1
2
3.5
mA
VDD=0.5V,HV=100V
0.3
0.57
0.85
mA
5
10
uA
5
20
uA
2.8
0.44
3.3
0.48
mA
mA
6.7
7.2
7.7
V
15.5
16.5
17.5
V
VDD=18V, HV=500V
VDD=UVLO(OFF)1V,
measure
leakage current into
VDD
VFB=3V, CL=1nF
VFB=0.5V, CL=1nF
Over
voltage
voltage
OVP
id
e
Vpull-up
protection
FB=3V
Ramp up VDD until
gate clock is off
Br
ig
ht
co
nf
Vth_latch
Latch release voltage
TD_recovery
Restart time for auto-recovery
(OB2632CP
protection
only)
Feedback Input Section(FB Pin)
VFB Open
VFB Open Loop Voltage
n-
Avcs
O
Maximum duty
cycle
Vref_rising
Vref_green
Vref_burst_H
Vref_burst_L
PWM input gain ∆VFB/∆VCS
Max
duty
cycle
@
VDD=14V,VFB=3V,VCS=0.3V
The threshold enter rising
frequency mode
The threshold enter green
mode
The threshold exit burst mode
The threshold enter burst
mode
IFB_Short
FB pin short circuit current
VTH_Openloop
The open loop FB Threshold
©On-Bright Electronics
鸣
Unit
nt
UVLO(OFF)
Max
鑫
晨
Iop_VDD
Iop_VDD_Burst
Typ.
o
VDD Start up Current
Min
lt
Istartup
Test Conditions
ia
(TA = 25℃, VDD=18V, unless otherwise noted)
Symbol
Parameter
HV Startup (OB2632CP only)
Supply current from HV pin
IHV1
@VDD>1V
Supply current from HV pin
IHV2
@VDD95uA
80
%
Iovp>243uA
3.5
V
1.85
V
1.2
V
1.1
V
210
uA
4.5
V
Short FB pin to GND
and measure current
Confidential
6
Preliminary datasheet
OB_DOC_DS_263201
OB2632
Adaptive Multi-Mode PWM Controller
Vref_PK_clamp
Vref_OCP
Fosc_low
Fosc_PK
△f_Temp
O
n-
△f_VDD
F_Burst
Gate driver
VOL
VOH
V_clamping
T_r
T_f
30
KΩ
4
300
ms
ns
90
ns
VDD=15V, FB=3V,
Iovp>95uA
0.50
0.52
0.84
0.296
92
100
0.305
65
V
us
108
60
60
V
V
2.5
uA
ms
70
KHz
IOVP243uA
125
KHz
+/-7
240
%
Hz
1
%
1
23
%
KHz
Frequency jittering
Shuffling frequency
Frequency
Temperature
Stability
Frequency Voltage Stability
Burst Mode Switch Frequency
Output low level @ VDD=15V,
Io=20mA
Output high level @
VDD=15V, Io=20mA
Output clamp voltage
Output rising time 1.2V ~
10.8V @ CL=1000pF
Output falling time 10.8V ~
1.2V @ CL=1000pF
©On-Bright Electronics
ms
鑫
晨
id
e
Peak frequency
0.287
Br
ig
△f_OSC
F_shuffling
Normal
Fixed
Oscillation
Frequency of high output
voltage
Normal
Fixed
Oscillation
Frequency of low output
voltage
nf
FOSC_nom
co
TD_OCP
Oscillator
ht
IOCP_ADJ
0.48
nt
Td_cs_pk_ADJ
Internal
Current
Limiting
Threshold Voltage with zero
duty cycle
CS voltage clamper
Internal
OCP
protection
voltage threshold
The delay time from PWM off
to
CS
peak
clamping
adjustment start point
Output current from CS pin
when PWM turns off
OCP Debounce Time
o
Vref_PK
lt
TD_OC
From Over Current
Occurs till the gate
driver output starts
to turn off
ia
Over Current Detection and
Control Delay
40
鸣
Voltage
The open loop protection
TD_ Openloop
debounce Time
ZFB_IN
Input Impedance
Current Sense Input(CS Pin)
SST_CS
Soft start time of CS threshold
T_blanking
Leading edge blanking time
1
8
Confidential
7
V
V
11.5
V
140
ns
55
ns
Preliminary datasheet
OB_DOC_DS_263201
OB2632
Adaptive Multi-Mode PWM Controller
SCP threshold
SCP debounce time
77
VAC
RHV=200 KΩ
70
77
85
VAC
27
32
37
ms
鸣
70
鑫
晨
30
OTP Level
126
uA
1.14
1.2
1.26
V
o
lt
360
Cycles
380
uA
8
2.5
1.8
23
8
Cycles
us
us
uA
Cycles
155
℃
125
℃
O
n-
Br
ig
ht
co
nf
OTP exit
120
340
FB=2.5V
FB=1.5V
T95uA), and it operates
at a 45KHz (typical) fixed frequency of low output
voltage (Iovp243uA). In peak power
mode, frequency is increased from 65KHz (typical)
to 125KHz (typical).
At light load, OB2632 enters the light load mode,
where the output current is reduced. The
switching losses are reduced by lowering the
switching frequency.
Fig3 Valley detection
o
Dual Function of External OTP and Output
OVP/SCP
On-Bright proprietary dual function of external
OTP and output OVP provides feasible and
accurate detection of external OTP through NTC
resistor and output OVP. The dual function is
realized through time-division technology as
shown in the figure 4.
ia
co
nf
id
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nt
Current Sensing and Leading Edge Blanking
Cycle-by-Cycle current limiting is offered in
OB2632 current mode PWM control. The switch
current is detected by a sense resistor into the CS
pin. An internal leading edge blanking circuit
chops off the sensed voltage spike at initial
internal power MOSFET on state due to snubber
diode reverse recovery and surge gate current of
power MOSFET. The current limiting comparator
is disabled and cannot turn off the power
MOSFET during the blanking period. The PWM
duty cycle is determined by the current sense
voltage and the FB voltage.
lt
Fig2 Frequency vs Feedback voltage
Br
ig
ht
Internal Synchronized Slope Compensation
Built-in slope compensation circuit adds voltage
ramp into the current sense input voltage for PWM
generation. This greatly improves the close loop
stability at CCM and prevents the sub-harmonic
oscillation and thus reduces the output ripple
voltage.
n-
Demagnetization Detection
The transformer core demagnetization is detected
by monitoring the voltage activity on the auxiliary
windings through PRT pin. This voltage features a
flyback polarity. After the on time (determined by
the CS voltage and FB voltage), the switch is off
and the flyback stroke starts. After the flyback
stroke, the drain voltage shows an oscillation with
Fig4 PRT Pin protection timing
O
There is a 30uA(typical) bias current outflow when
S2=1, that’s S0= “1” or S1= “1”. For external OTP
detection, when switch control signal S1= “1”, the
30uA (typical) current flows out from PRT pin.
When switch control signal S0= “1”, another
120uA (typical IRT) current flows out from PRT
pin in addition to 30uA.
a frequency of approximately 1 / 2
L p Cd ,
where Lp is the primary self inductance of primary
winding of the transformer and Cd is the
capacitance on the drain node.
The typical detection level is fixed at 85mV(typical)
at the PRT pin. Demagnetization is recognized by
detection of a possible “valley” when the voltage
at PRT is below 85mV in falling edge.
©On-Bright Electronics
So the PRT pin voltage V1(s0) at phase S1=“1” is:
V 1( s1)
Confidential
12
ROVP VD RT Vaux RT ROVP 30uA
ROVP RT
Preliminary datasheet
OB_DOC_DS_263201
OB2632
Adaptive Multi-Mode PWM Controller
The PRT pin voltage V1(s1) at phase S0=“1” is
V 1( s0)
range and its dependency on primary inductance
and frequency is removed.
At overload condition when FB input voltage
exceeds power limit threshold value for more than
Td_OLP, control circuit reacts to shut down the
converter. It restarts when VDD voltage drops
below UVLO limit. For protection with latched shut
down mode, control circuit shuts down (latch) the
power MOSFET when an over temperature
condition or over voltage condition is detected
until VDD drops below 4.8V (typical) (Latch
release voltage), and the device enters power on
restart-up sequence thereafter.
ROVP VD RT Vaux RT ROVP(30uA 120uA)
ROVP RT
Vaux is the auxiliary winding demagnetization
voltage.
VD is D1 forward voltage.
ROVP and RT are shown in fig4.
鸣
Voltage difference of ∆Votp at phase S0 and S1
phase is
鑫
晨
RT ROVP
120uA
ROVP RT
This voltage difference cancels the effect of D1
diode forward voltage.
Votp V 1( s 0) V 1( s1)
Iovp _ th N sec .ROVP
V diode
N aux
lt
ia
id
e
V outovp
nt
For output OVP detection, when Sovp= “1”, Iovp is
equal to (Naux/Nsec)*(Vout+Vdiode)/ROVP. If
Iovp is larger than 360uA (typical Ioutput_ovp),
larger output OVP is triggered. The output OVP
voltage is calculated as
o
When ∆Votp< VOTP (1.2V typical), external OTP
latch protection is triggered after 60 (typical) PWM
cycles debounce.
Programmable OCP and Peak output Current
Controls
In order to meet peak current output requirement,
OB2632 sets up two levels output current
protection thresholds. The two thresholds
correspond to the normal OCP protection and
peak power protection respectively. When output
current exceeds the OCP threshold for 60ms
(typical), OCP protection occurs. The OCP loop
ensures the output OCP has a very tight range
and is only related with turns ratio and Rsense.
The specification for output OCP protection
voltage threshold, Vref_OCP, is 0.296V (typical).
nf
Nsec is transformer secondary winding turns,
Naux is transformer auxiliary winding turns,
Vdiode is the secondary output diode forward
voltage .
I out _ OCP
co
N is the ratio of transformer primary winding turns
to secondary winding turns.
OVP latch protection is triggered after 8 Gate
cycles debounce. By selecting proper Rovp
resistance, output OVP level can be programmed.
Vref_OCP
100uA
For output SCP detection, when Sovp= “1”, Iscp is
equal
to
(Naux/Nsec)*(Vout+Vdiode)/ROVP.
During the 15ms after the IC startup, if Iscp is less
than 23uA (typical Iscp), SCP is triggered. The
output SCP voltage calculation method is the
same as output OVP detection.
OCP
ht
PWM OFF
Br
ig
R1
CS
Rsense
Sampling
voltage
OCP ref
compensation
VTH_PK
PWM
n-
SCP auto-recovery protection is triggered after 8
Gate cycles debounce. By selecting proper Rovp
resistance, output SCP level can be programmed.
FB
CV
O
Fig.5 Programmable OCP and PK load protection
Protection Controls
Good power supply system reliability is achieved
with auto-recovery protection features including
OCP, output short protection, Under Voltage
Lockout on VDD (UVLO) and peak load protection,
and latched shutdown features including Over
Temperature Protection (OTP), VDD and output
Over Voltage Protection (OVP).
With On-Bright proprietary technology, the OCP is
line voltage compensated to achieve constant
output OCP limit over the universal input voltage
©On-Bright Electronics
N Vref _ OCP
Rsense
OB2632 provides an adaptive cycle-by-cycle OCP
compensation method varying with gate on duty
cycle in Fig6. The maximum cycle-by-cycle OCP
threshold voltage, Vth_PK, is 0.84V(typical).
At PWM off state, 100uA current flows out of CS
pin to generate a voltage through R1 and Rsense.
The final CS peak clamping voltage threshold is
adjusted by the added voltage.
Vth _ PK _ final Vth _ PK 100uA R1
Confidential
13
Preliminary datasheet
OB_DOC_DS_263201
OB2632
Adaptive Multi-Mode PWM Controller
Pin Floating and Short Protection
OB2632 provides PIN floating protection for all the
pins and pin short protection for adjacent pins. In
the cases when a pin is floating or two adjacent
pins are shorted, Gate switching is disabled.
鸣
Driver
The power MOSFET is driven by a dedicated gate
driver for power switch control. Too weak the gate
driver strength results in higher conduction and
switch loss of MOSFET while too strong gate
driver strength results the compromise of EMI.
A good tradeoff is achieved through the built-in
totem pole gate design with right output strength
and dead time control. The low idle loss and good
EMI system design is easier to achieve with this
dedicated control scheme.
o
ia
lt
Intelligent Brown-in and Brown-out protection,
AC off detection with X-CAP discharge
function(OB2632CP only)
A precise brown-in and brown-out detection is
implemented by monitoring the rectified AC
voltage on HV pin. The final brown in or out
threshold is adjusted by the HV resistor in Fig. 9.
id
e
nt
Two level OCP Controls
In order to meet peak current output requirement
under high output level(Iovp>243uA), OB2632
sets up two levels OCP protection thresholds. The
two thresholds correspond to the normal OCP
protection and peak power protection respectively,
and these two threshold values are internally
compensated. When primary side inductor current
exceeds the OCP threshold, OCP timer will begin
counting. After 60ms (typical), OCP protection
occurs.
When primary side inductor current exceeds the
peak power threshold, over peak power timer will
begin counting. After 40ms (typical), peak load
protection occurs. OCP and peak power
protection are mutually independent and do not
affect each.
鑫
晨
Fig6 Cycle by cycle OCP compensation
nf
Output
Current
Pk Load
co
OCP
40ms
Timer
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