Microchip HV9861ADB1 Manual de Usario

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Supertex inc.
Supertex inc.
www.supertex.com
HV9861ADB2
Doc.# DSDB-HV9861ADB2
A032713
General Description
Certain target markets for LED lighting require a power factor
of at least 90%. A power factor over 90% can be attained
using valley ll power factor correction with the addition of a
small boost converter.
The boost converter lowers line current distortion by adding
line current draw in the valley and lowering the peak
amplitude of the valley ll capacitor recharging current.
HV9861A LED Driver Demoboard
Boost Assisted, Valley Fill,
120VAC Input, 7W Output, 350mA, 20V, Power Factor ~ 93%
Basic valley ll circuit operation
A valley ll power factor correction circuit operates in two
distinctly different modes.
During a rst period, here referred to as the valley and
coinciding with line voltage being lower than half the peak
line voltage, the load is exclusively powered from two energy
storage capacitors. Consequently, in the valley the line
current is equal to zero. The valley, being characterized by a
line voltage less than half the peak line voltage, extends 30°
on either side of the line voltage zero crossing.
During a second period, coinciding with the line voltage being
higher than half the peak voltage, the load is exclusively
powered from the line and not from the valley ll capacitors.
Consequently, the line current is not zero. Furthermore, an
additional line current is drawn near the peak of the line
voltage for recharge of the valley ll capacitors. The two
line current components can clearly be identied in the
oscillogram of the line current.
Boost converter operation
The boost converter adds current draw in the valley, thereby
lowering distortion and raising power factor.
The boost converter switch, a bipolar transistor in common
base conguration, is driven indirectly by the current ow in
the valley capacitors. In the valley, current is extracted from
the valley capacitors during ON time of the main switch, each
capacitor contributing half of the load current. The capacitor
current in one of the capacitors develops a voltage of about
1.2V across two diodes in series. This voltage provides a
forward bias for the base emitter circuit of the boost transistor.
Current develops in the boost inductor, which subsequently
ows in to the valley capacitors during OFF time.
The boost converter develops a line current with an
amplitude which is line voltage dependent. When line
voltage is particularly small the boost converter operates
in discontinuous mode (DCM) and when the line voltage
approaches half the peak voltage the converter operates
in continuous conduction mode (CCM). The line current
amplitude increases nonlinearly with line voltage in either
conduction mode. The boost converter action results in
delivery of power to the valley capacitors thereby lowering
the amplitude of the capacitor recharging current during the
second period.
Circuit add-ons
PF 93. PF 90.6 % 8 %
without boost seconwith boost secon
2
Supertex inc.
www.supertex.com
HV9861ADB2
Doc.# DSDB-HV9861ADB2
A032713
Specications
Parameter Value
Input voltage 100 … 135VAC
Output voltage 20VDC, ±10%
Output current 350 mADC, ±5%
Output power 7W
Power factor ~93.6%
Total harmonic distortion ~35%
EMI limits CISPR 15
Parameter Value
Efciency ~80%
Output current ripple (at FSW) 80%PP (See note)
Output open circuit protection Yes
Output short circuit protection Yes
Switching frequency 50kHz … 60kHz
Dimensions 54mm x 24mm x 20mm
Connection Diagram
Note:
Output current ripple can be reduced in straightforward manner by increasing inductor L3. Alternatively, capacitor
C4 can be increased.
Connections
Connect the mains voltage at the input terminals and connect the LED load at the output terminals as shown.
Warning: The mains voltage circuit does not contain galvanic isolation. Do not ground any part of the circuit
directly to protective ground by means of test equipment connections.
120VAC
20VDC
Circuit Schematic
+
+
VIN
VDD RT GND
GATE
CS
PWMD
LD
R6
2k
R7
2k
R2
100
R1
100
R3
2
R4
1.3
R5
332k
C7
100n
C2
10µ
C4
220n
C3
100n
C6
10µ
C1
33n
D3
FMT108
D5
RM4007
D6
FMT108
DN1
BAV99
D7
D914
D1
RM4007
D2
FMT108
D4
FMT108
AN0 RED TP31
CAT BLU TP32
BR1
MS380
L4
1.5m
L2
1.5m
F1
1ATP11 AC11 AC1
TP22 AC22 AC2
MOV1
S07K140
C5
33n
L3
1m
1
2
3
1
2
3
1
2
3
4
1
2
3
6 8 3
4
1
27
HV9861A
Q1
STX616
L1
1.5m
M1
M1N60
5
3
Supertex inc.
www.supertex.com
HV9861ADB2
Doc.# DSDB-HV9861ADB2
A032713
V
AC
%
THD vs. Line Voltage
80 100 120 140 160
0
20
40
60
80
100
V
AC
%
PF vs. Line Voltage
80 100 120 140 160
50
60
70
80
90
100
V
AC
%
Efficiency vs. Line Voltage
80 100 120 140 160
50
60
70
80
90
100
V
AC
mA
Output Current vs. Line Voltage
80 10 12 14 160 0 0 0
0
100
200
300
400
500
EMI Signature
100
10k 100k 1M 10M
dBμV
If BW 9.0kHz
80
60
40
Hz
Notes:
PCB suspended approximately 3 inches above reference plane.
Peak detector in peak hold mode for 10 min.

Especificaciones del producto

Marca: Microchip
Categoría: No categorizado
Modelo: HV9861ADB1

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