Datasheet

Operating Instructions www.ti.com
6 Operating Instructions
The following instructions give general instructions for use of LP3972 with the evaluation board. Practice
standard ESD protection (ground cable) to prevent any unwanted damaging ESD events.
1. Check that the jumpers are in default settings (jumpers are introduced later in this document).
2. Load version .202 or later of the codeloader program into PC.
3. Connect the USB cable [standard USB AB cable] from the USB connector to PC port.
4. Open the codeloader program up, verify that “USB” port has been selected.
5. Verify that successful communications link has been established by toggling “READ ALL”.
6. If there is no communication, key the USB RST [SW1] switch once on the board for reboot.
7. If the voltmeter monitoring function is desired, select “POLL STATUS”.
8. LDO/buck outputs may be monitored directly off the appropriate header output pins.
9. Note that for full load testing, an external PS must be connected to TP1/TP2 and jumper J1 must be
removed. This is because the USB port source spec is limited to 500 mA and removing the jumper will
disconnect the USB supply.
10. PWR EN/SYS En is selectable via codeloader software assignment.
11. Hardware reset can be accomplished by pressing the nREST_In momentary switch.
12. Battery backup is possible by inserting appropriate rechargeable cell into supplied holder.
13. Switches PKEY, nTJ, and SP, are provided for use in normal evaluation mode.
7 List of Components
Item Qty Reference Value Pkg. Manuf. Part Number
1 5 C1,C21,CC,CD,CF1 10 µF 0805 Panasonic ECJ2FF1A106Z
2 2 C2,C3 100 µF 3528-21 Kemet T520B107M006ASE040
3 8 C4,C7,C13,C15,C16,C31,CA 1 µF 0805 Kemet C0805C105K4RACTU
,CB
4 6 C5,C6,C8,C9,C25,C29 10 µf 1206 Taiyo-Yuden JMK316BJ106M
5 6 C14,C19,C20,C23,C24,C26 0.47 µF 0805 TDK C2012X7R1E474K
6 2 C17,C18 47 pF 0805 Murata GRM2195C2A470JZ01D
7 4 C22,C30,C32,C33 0.1 µF 0805 Murata GRM21BR71E104KA01L
8 2 C27,C28 15 pF 0805 Yageo 0805CG150J9B200
9 1 BT2 Battery Holder SMT Seiko BH0414
10 1 NOT INSTALLED Backup Battery Micro4 Seiko MS412F
11 4 D6,D7,D10,D11 Schottky PM 457 On Semi MBRM120LT3
12 2 D8 (PWR EN), D9 (SYS EN) Green LED 1206 Lumex SML-LX1206GC-TR
13 9 LDO1(D13), LDO2(D14), Red LED 1206 Lumex SML-LX1206IC-TR
LDO3(D18), LDO4(D17),
LDO5(D19), LDORTC(D16)
D2,D3,D12
14 2 L1,L2 1 µH Inductor 0805 TDK MLF2012A1R0K
15 3 L3,L4,L5 2.2 µH Inductor SMT Toko FDSE0312
16 1 Q1 XTAL 24 MHz 18 PF SMD Citizen HCM49-24.000MABJT
17 7 R1,R2,R23,R31,R32,R33,R3 330Ω 0805 SEI 807065R330
4
18 1 R8 100Ω 0805 NIC NRC10J101TR
19 1 R9 49.9Ω 0805 Rohm MCR10EZHF49R9
20 11 R10,R11,R12,R17,R18,R22, 10K 0805 Yageo 9C08052A1002FKHFT
R24,R26,R27,R36,R37
21 1 R12 0Ω 0805 Yaego 9C08052A0R00JLHFT
4
AN-1621 LP3972 USB Evaluation Board Rev B SNVA235A–May 2007–Revised April 2013
Submit Documentation Feedback
Copyright © 2007–2013, Texas Instruments Incorporated