Datasheet

LT3751
25
3751fc
Typical applicaTions
42A Capacitor Charger
CHARGE
CLAMP
V
CC
DONE
FAULT
UVLO1
OVLO1
UVLO2
OVLO2
RDCM
RV
OUT
HVGATE
LVGATE
CSP
CSN
FB
RV
TRANS
T1**
1:10
D1
V
OUT
500V
V
TRANS
12V TO 24V
V
CC
3751 TA02
LT3751
GND RBG
R6
40.2k
OFF ON
C3
1000µF
C2
10µF
×3
V
CC
12V TO 24V
C1
10µF
•
•
R7, 18.2k
R8, 40.2k
M1, M2*
R5
2.5mΩ
D2***
+
+
C4
1200µF
R9
787Ω
V
TRANS
V
CC
R10, 100k
R11, 100k
R1, 191k
R2, 475k
R3, 191k
R4, 475k
C1: 25V X5R OR X7R CERAMIC CAPACITOR
C2: 25V X5R OR X7R CERAMIC CAPACITOR
C3: 25V ELECTROLYTIC
C4: HITACHI FX22L122Y 1200µF, 550V ELECTROLYTIC
OR: CORNELL DUBILIER DCMC192T550CE2B 1900µF, 550V ELECTROLYTIC
D1, D2: VISHAY GURB5H60 600V, 5A ULTRAFAST RECTIFIER
M1, M2: 2 PARALLEL VISHAY SUP33N20-60P 200V, 33A NMOS
R1 THRU R4, R6 THRU R11: USE 1% 0805 RESISTORS
R5: USE 2 PARALLEL 5mΩ IRC LR SERIES 2512 RESISTORS
T1: COILCRAFT GA3460-BL 50A SURACE MOUNT TRANSFORMER
DANGER HIGH VOLTAGE! OPERATION BY HIGH VOLTAGE TRAINED PERSONNEL ONLY
FOR ANY V
OUT
VOLTAGE BETWEEN
50V AND 500V SELECT R9 ACCORDING TO:
4.7nF
Y-RATED
* M1, M2 REQUIRES PROPER
HEATSINK/THERMAL DISSIPATION
TO MEET MANUFACTURER’S SPECIFICATIONS
** THERMAL DISSIPATION OF T1 WILL LIMIT
THE CHARGE/DISCHARGE DUTY CYCLE OF C4
*** D2 MAY BE OMITTED FOR OUTPUT
VOLTAGE OPERATION BELOW 300V
Efficiency Output Capacitor Charge Times Charging Waveform
OUTPUT VOLTAGE (V)
50
EFFICIENCY (%)
85
80
75
70
65
450
3751 TA02b
250 350150
V
TRANS
= 12V
V
TRANS
= 24V
OUTPUT CAPACITANCE (µF)
200
CHARGE TIME (ms)
1200
800
400
0
1000
3751 TA02c
1200800600400
V
OUT
= 500V, V
TRANS
= 24V
V
OUT
= 500V, V
TRANS
= 12V
V
OUT
= 300V, V
TRANS
= 24V
V
OUT
= 300V, V
TRANS
= 12V
V
OUT
= 100V,
V
TRANS
= 24V
V
OUT
= 100V,
V
TRANS
= 12V
100ms/DIV
3751 TA02d
V
OUT
= 500V
V
TRANS
= 24V
C4 = 1200µF
AVERAGE
INPUT
CURRENT
5A/DIV
V
OUT
100V/DIV
R9 = 0.98 • N •
40.2kΩ
V
OUT
+ V
DIODE





