CRA2512-FZ-R075ELF datasheet(15/28 Pages) ONSEMI

15 / 28 page

EVBUM2775/D

www.onsemi.com

Current Measurement and Over−Current Protection

Schematic of current measurement and over−current

protection can be seen in the Figure 17. Information about

currents is provided via 39 m

W shunt resistors. Voltage drop

from shunt resistor is going to input of operational amplifier

(op−amp) NCS2003 which gain is set to 4.99 with 1k resistor

and 4k99 resistor connected as negative feedback. U7

(TLV431) is creating 1.65 V reference which is connected

to non−inverting input of op−amps. This connection

provides voltage offset at the output of op−amps, which is

needed for negative current measurement.

Overcurrent

protection

offered

NCS2250

comparator. Comparator threshold is set by voltage divider

which consists of R68, R71 and C48. Signals from shunt

resistors are going via R78, R81 and R84 connected to

non−inverting input. These resistors together with C58 are

also acting as low pass filter for high frequency signals

interference. On the one hand, with insufficient filtering the

over− current protection can react for lower values of current

even if there is 350 ns blanking time on ITRIP pin of IPM to

improve noise immunity (see datasheet of IPM). On the

other hand, when we are designing this filter it is needed to

be careful about the maximal time constant value according

short circuit safe operating area (see datasheet of IPM,

NFAQ1060L36T− for VCE = 400 V is 4

ms). Output from

comparator is connected to ITRIP pin of IMP module. As

was mentioned in previous chapter, IPM has fault pin and its

voltage level is high during normal state. An over−current

condition is detected if the voltage on the ITRIP pin is larger

than the reference voltage (typically 0.5 V). After a

shutdown propagation delay of typically 1.1

ms, the FAULT

output is switched on. The FAULT output is held on for a

time determined by the resistor and capacitor connected to

the RCIN pin (IPM pin 12). If R44 = 2 M

Ω and C34 = 1 nF,

the FAULT output is switched on for 1.65 ms (typical). The

over−current protection threshold should be set to be equal

or lower to 2 times the module rated current. The reaction of

the protection can be seen in the Figure 18 and 19. System

is also using ENABLE pin of the IPM. After the

over−current fault, fault signal is generated and sent to

microcontroller which disable the IPM via ENABLE pin

(programmed by user). New operation is possible after

microcontroller reset.

Figure 17. Schematic of Current Measurement and Overcurrent Protection

C49

100 nF

I_U

I_V

I_W

R77

680R

R79

R82

TLV431

IN−

IN+

OUT

NCS2250SN2T3G

3V3

R67

R69

C50

100 pF

U_pos

V_pos

W_pos

C_SENSE

R70

R72

C53

100 pF

R73

R75

C56

100 pF

G_IPM

R78

100R

R76

215k

C60

10 nF

R81

100R

R84

100R

3V3

G_IPM

ITRIP

I_SENSE

I_V

I_W

I_U

I_SENSE

C61

3V3

G_IPM

R68

21.5 k

R71

C48

100 nF

G_IPM

C58

15 nF

G_IPM

R80

4k99

R85

4k99

R87

4k99

R83

4k99

R86

4k99

R74

4k99

C52

10 nF

C54

10 nF

C55

10 nF

G_IPM

C57

10 nF

IN−

IN+

OUT

NCS2003SN2T1G

IN−

IN+

OUT

NCS2003SN2T1G

IN−

IN+

OUT

NCS2003SN2T1G

3V3

G_IPM

C59

100 nF

C62

10 nF

3V3

C63

100 nF

C64

10 nF

G_IPM

3V3

CRA2512-FZ-R075ELF датащи(PDF) 15 Page - ON Semiconductor

CRA2512-FZ-R075ELF датащи(HTML) 15 Page - ON Semiconductor

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

датащи скачать

ссылки URL