Switching Power Supply (SPS) Design Notes for (Launch Vehicle 2b) LV2b

LV2b SPS Schematic:

---------- Integrated Circuits (ICs) ----------

Step-Down Switching Voltage Regulator (Buck Topology) (U200)

Part Description:

Main SPS Switching Buck Regulator at +3.3V rail and Io,max ~ 400 mA. Monolithic Step-Down Buck Switching Regulator, Current Mode Control, 1.5 A, 1.25 MHz (Adjustable), 3V < Vin < 25 V, 8-MSOP (No exposed ground/thermal pad), RoHS Non-Compliant, Linear Technology, LT1767EMS8 (Digikey p/n LT1767EMS8-ND $6.00/1) Datasheet

Purpose:

Specifications/ Calculations:

Overcurrent/Circuit-Breaker Protection (U250)

Part Description:

MAX5902AAETT +72 V, SOT-23, Simple Swapper How-Swap Controller. Ordered samples from vendor no Digi-Key. Datasheet.

Purpose:

Specifications/ Calculations:

Undervoltage/Overvoltage Protection (U251)

Part Description:

Nanopower Push-Pull Output Comparator with Voltage Reference, 1.8 V < Vin < 5.5 V, SOT-23-6, Tape & Reel (TR), RoHS Compliant, Texas Instruments, TLV3012AIDBVT (Digikey p/n 296-16830-2-ND $262.50/250) NOTE: Ordered samples from vendor no Digi-Key. Datasheet.

Purpose:

Specifications/ Calculations:

---------- Discrete Components ----------

Power Bus Fast-Acting Fuse (F200)

Part Description:

500 mA, 50 V, 1206, Fast Acting Short Time Lag, RoHS Compliant, Wickmann USA Inc, FCD120500TP (Digikey p/n WK6213CT-ND $0.56/1) Datasheet.

Purpose:

Specifications/ Calculations:

MAX5902 External P-MOSFET (Q250)

Part Description:

-60 V, -3 A, SOT-23-6, P-Channel MOSFET, Cut Tape, RoHS Compliant, Zetex Inc, ZXMP6A17E6TA (Digikey p/n ZXMP6A17E6CT-ND $1.04/1) Datasheet.

Purpose:

Specifications/ Calculations:

TLV3012AIDBVT External Logic-Level N-MOSFET (Q251)

Part Description:

100 V, 170 mA, RDS(on) = 10 ohm @ Vgs = 4.5V, SOT-23, Cut Tape, RoHS Compliant???, N-Channel Logic-Level MOSFET, Infineon Technologies, BSS123E6327 (Digikey p/n BSS123INCT-ND $0.36/1) Datasheet.

Purpose:

Specifications/ Calculations:

Power Bus Input Voltage Suppressor (TVS200)

Part Description:

18 V, SMB, Unidirectional, Cut Tape, RoHS Non-Compliant, Diodes Inc, SMBJ18A-13 (Digikey p/n SMBJ18ADICT-ND $0.89/1) Datasheet.

Purpose:

Specifications/ Calculations:

---------- Diodes ----------

Buck (Catch) Schottky Diode (CR200)

Part Description:

30 V, 1.5 A, 4 ns, New MiniPower 2P, Cut Tape, RoHS Compliant???, Panasonic - SSG, MA2Q70500L (Digikey p/n MA2Q70500LCT-ND $0.83/1) Datasheet.

Purpose:

Specifications/ Calculations:

Boost Rectifier Diode (CR201)

Part Description:

180 V, 0.6 A, SOT-23, Cut Tape, RoHS Compliant, Micro Commercial Co., MMBD1501-TP (Digikey p/n MMBD1501TPMSCT-ND $2.00/10)
Datasheet.

Purpose:

Specifications/ Calculations:

TLV3012AIDBVT "Secondary Power Supply" Schottky Diode (CR250)

Part Description:

30 V, 1.5 A, 4 ns, New MiniPower 2P, Cut Tape, RoHS Compliant???, Panasonic - SSG, MA2Q70500L (Digikey p/n MA2Q70500LCT-ND $0.83/1) Datasheet.

Purpose:

Specifications/ Calculations:

SPS Secondary Buck (Catch) Schottky Diode (CR251)

Part Description:

30 V, 1.5 A, 4 ns, New MiniPower 2P, Cut Tape, RoHS Compliant???, Panasonic - SSG, MA2Q70500L (Digikey p/n MA2Q70500LCT-ND $0.83/1) Datasheet.

Purpose:

Specifications/ Calculations:

SPS Output Power On LED (D201)

Part Description:

1.9 V, 90 mcd @ 20 mA, 609 nm, 0805, Orange Diffused LED, CML Innovative Technologies Inc, CMDA5BA7D1S (Digikey p/n L71515CT-ND $3.00/10) Datasheet.

Purpose:

Specifications/ Calculations:

---------- Resistors ----------

LT1767 FB Resistor Network: (R200, R201)
R200:

Part Description:

10.0 kohm, 0805, 1%, 1/8 W, Cut Tape, RoHS Compliant???, Rohm, MCR10EZHF1002 (Digikey p/n RHM10.0KCCT-ND $0.38/10) Datasheet.

Purpose:

Specifications/ Calculations:

R201:

Part Description:

17.4 kohm, 0805, 1%, 1/8 W, Cut Tape, RoHS Compliant???, Rohm, MCR10EZHF1742 (Digikey p/n RHM17.4KCCT-ND $0.38/10) Datasheet.

Purpose:

Specifications/ Calculations:

LT1767EMS8 Frequency Compensation Resistor (R206)

Part Description:

Purpose:

Specifications/ Calculations:

LT1767EMS8 UVLO Lockout Resistor Network: (R209, R210)
R209

Part Description:

60.4 kohm, 0805, 1%, 1/8 W, Cut Tape, RoHS Compliant???, Rohm, MCR10EZHF6042 (Digikey p/n RHM60.4KCCT-ND $0.38/10) Datasheet.

Purpose:

Specifications/ Calculations:

R210

Part Description:

10.0 kohm, 0805, 1%, 1/8 W, Cut Tape, RoHS Compliant???, Rohm, MCR10EZHF1002 (Digikey p/n RHM10.0KCCT-ND $0.38/10) Datasheet.

Purpose:

Specifications/ Calculations:

SPS Output Power On LED Current Limiter Resistor (R214)

Part Description:

649 ohm, 0805, 1%, 1/8 W, Cut Tape, RoHS Compliant, Rohm, MCR10EZHF6490 (Digikey p/n RHM649CCT-ND $0.38/10) Datasheet.

Purpose:

Specifications/ Calculations:

DC Path From SPS Node GND to Chassis GND Resistor (R215)'

Part Description:

100 kohm, 0805, 1%, 1/8 W, Cut Tape, RoHS Compliant, Rohm, MCR10EZHF1003 (Digikey p/n RHM100KCCT-ND $0.38/10) Datasheet.

Purpose:

Specifications/ Calculations:

MAX5902 Circuit-Breaker Resistor Network (R250, R251)
R250

Part Description:

61.9 kohm, 0805, 1%, 1/8 W, Cut Tape, RoHS Compliant???, Rohm, MCR10EZHF6192 (Digikey p/n RHM61.9KCCT-ND $0.38/10) Datasheet.

Purpose:

Specifications/ Calculations:

R251

Part Description:

10.0 kohm, 0805, 1%, 1/8 W, Cut Tape, RoHS Compliant???, Rohm, MCR10EZHF1002 (Digikey p/n RHM10.0KCCT-ND $0.38/10) Datasheet.

Purpose:

Specifications/ Calculations:

MAX5902AAETT Circuit-Breaker External P-MOSFET RDS(on) Additional Series Resistor (R252)

Part Description:

0.82 ohm, 0805, 1%, 1/8 W, Cut Tape, RoHS Compliant???, Panasonic - ECG, ERJ-6RQFR82V (Digikey p/n P.82DCT-ND $2.10/10) Datasheet. Note: This value may change due to board level testing results.

Purpose:

Specifications/ Calculations:

TLV3012AIDBVT Overvoltage Detection External N-MOSFET Current Limiting Resitor (R253)

Part Description:

47.0 kohm, 0805, 1%, 1/8 W, Cut Tape, RoHS Compliant???, Rohm, MCR10EZHF4702 (Digikey p/n RHM47.0KCCT-ND $0.38/10) Datasheet.

Purpose:

Specifications/ Calculations:

TLV3012AIDBVT UVLO Lockout Resistor Network (R254, R255)
R254

Part Description:

18.2 kohm, 0805, 1%, 1/8 W, Cut Tape, RoHS Compliant???, Rohm, MCR10EZHF1822 (Digikey p/n RHM18.2KCCT-ND $0.38/10) Datasheet.

Purpose:

Specifications/ Calculations:

R255

Part Description:

10.0 kohm, 0805, 1%, 1/8 W, Cut Tape, RoHS Compliant???, Rohm, MCR10EZHF1002 (Digikey p/n RHM10.0KCCT-ND $0.38/10) Datasheet.

Purpose:

Specifications/ Calculations:

---------- Inductors ----------

Split Buck Inductor (L200a, L200b)

Part Description:

SD3118-470-R Low Profile Power Inductor 47 uH, Shielded Drum Package (Bobbin), RoHS Compliant???, Tape and Reel The SD3118-470-R datasheet from Coiltronics.

Purpose:

Specifications/ Calculations:

Power Bus Input Choke (L201, L202)

Part Description:

CMS1-11-R Common Mode Inductors 100 uH, Micro-PAC Plus Package, RoHS Compliant, Tape and Reel. The CMS1-11-R datasheet from Coiltronics.

Purpose:

Specifications/ Calculations:

----------Capacitors----------

Buck Output Cap (C200)

Part Description:

22 uF, 6.3 V, 0805, X5R, Cut Tape, RoHS Compliant, Panasonic - ECG , ECJ-2FB0J226M (Digikey p/n PCC2401CT-ND $8.31/10) Datasheet.

Purpose:

Specifications/ Calculations:

Buck Input Cap (C201)

Part Description:

10 uF, 25 V, 1206, X5R, Cut Tape, RoHS Compliant, Panasonic-ECG, ECJ-3YB1E106K (Digikey p/n PCC2414CT-ND $5.45/10) Datasheet.

Purpose:

Specifications/ Calculations:

Boost Cap (C202)

Part Description:

0.1 uF, 50 V, 0805, X7R, Cut Tape, RoHS Compliant, Panasonic-ECG, ECJ-2YB1H104K (Digikey p/n PCC1840CT-ND $1.61/10) Datasheet.

Purpose:

Specifications/ Calculations:

Power Bus Input Caps (C203, C204)
C203 Part Description: 22 uF, 25 V, Tant, T491 Series, 7343-31 (EIA), Cut Tape, RoHS Compliant???, Kemet, T491D226K025AT (Digikey p/n 399-3782-1-ND $0.65/1) Datasheet.

Purpose:

Specifications/ Calculations:

C204 Part Description: 0.33 uF, 50 V, 0805, X7R, Cut Tape, RoHS Compliant, Murata Electronics North America , GRM219R71H334KA88D (Digikey p/n 490-3327-1-ND $3.09/10) Datasheet.

Purpose:

Specifications/ Calculations:

LT1767 Frequency Compensation Caps (C205, C206)
C205

Part Description:

Purpose:

Specifications/ Calculations:

C206

Part Description:

Purpose:

Specifications/ Calculations:

LT1767 FB Resistor Network Shunt Caps (C208, C209)
C208:

Part Description:

Purpose:

Specifications/ Calculations:

C209:

Part Description:

10 pF, 50 V, 0805, NPO, Cut Tape, RoHS Compliant???, BC Components, VJ0805A100JXACW1BC (Digikey p/n BC1256CT-ND $0.52/10) Datasheet.

Purpose:

Specifications/ Calculations:

LT1767 UVLO Resistor Network Shunt Cap (C210)

Part Description:

0.1 uF, 50 V, 0805, X7R, Cut Tape, RoHS Compliant???, BC Components , VJ0805Y104KXATW1BC (Digikey p/n BC1298CT-ND $0.72/10) Datasheet.

Purpose:

Specifications/ Calculations:

TLV3012AIDBVT "Secondary Power Supply" Cap (C250)

Part Description:

2.7 uF, 10 V, 0805, X5R, Cut Tape, RoHS Compliant, Kemet, C0805C275K8PACTU (Digikey p/n 399-3127-1-ND $7.02/10) datasheet.

Purpose:

Specifications/ Calculations:

TLV3012AIDBVT Overvoltage Detection Cap (C251)

Part Description:

0.015 uF, 100 V, 0805, X7R, Cut Tape, RoHS Compliant, AVX Corporation, 08051C153KAT2A (Digikey p/n 478-1359-1-ND $2.64/10) The Datasheet.

Purpose:

Specifications/ Calculations:

SPS Secondary Buck Output Cap (C252)

Part Description:

TBD Note: This is an application specific cap whose value is mostly independent from the SPS design.

Purpose:

Specifications/ Calculations:

Attachments:

SPS Design Schematic rev2 2.pdf