FEBSPM3SPM45_M01MTCA Fairchild Semiconductor, FEBSPM3SPM45_M01MTCA Datasheet - Page 25

• Manufacturer Part Number: FEBSPM3SPM45_M01MTCA
• Description: Power Management IC Development Tools FNB41560 Eval Board 2100W with Heatsink
• Manufacturer: Fairchild Semiconductor
• Type: Motor / Motion Controllers & Driversr
• Series: SPM3, SPM45Hr

Specifications of FEBSPM3SPM45_M01MTCA

• Rohs: yes
• Product: Evaluation Boards
• Tool Is For Evaluation Of: FNB41560
• Input Voltage: 265 VAC
• Output Voltage: 390 VDC
• Description/function: Evaluation board for Motion SPM3/45H
• Output Current: 7 A, 15 A
• For Use With: FNB41560

© 2012 Fairchild Semiconductor Corporation
8.2. Short-Circuit Protection (SCP) Circuit
One shunt resistor is used for sensing short-circuit (SC) current. The related circuit is
composed of an external shunt resistor, op amp, RC low-pass filter, fault indicator circuit,
and fault output pin. Refer to reference design
the SCP circuit shown in Figure 16. In this example, the ideal shunt resistor value is
8 mW The default shunt resistor used on this board is a 10 mWThe actual shunt resistor
value used is typically a balance between component count (if op amp is required due to
small resistor value) and shunt-resistor losses.
During a short-circuit condition, the SPM VFO pin is actively pulled down via the
internal open-collector transistor. This event lights the fault indicator LED (D3) and
sends the low FO signal to the MCU via J1-9. To reset fault and its indicator D3, press
fault-reset switch SW2.
Calculation Conditions







Installed SPM: FNB41560
Op Amp: FAN4274
Resistance of Shunt Resistor: 8 mW
SC Trip Current: 22.5 A (1.5 x I
SC Trip Reference Voltage: V
Refer to Figure 16
Alternatively, a larger value shunt resistor could be used without requiring an op amp
at the expense of higher losses in the sense resistor.
Figure 20.
Short-Circuit Protection Circuit
SC(min)=
25
C
(rated current), can be lowered by the designer)
0.45 V,
RD-344
VSC(typ)=
for a more detailed explanation of
0.5 V, V
FEBSPM3SPM45_M01MTCA • Rev. 1.0.1
SC(max)=
0.55 V