怎么进入MSP430F5310芯片的LPM3，最小系统的功耗都是26ua是什么原因？

#include <msp430.h>

//#define SYS14_WORKAROUND_REVE // Uncomment this line if using RevE silicon

#define INIT_MEMORY_ADDR1 0x0206
unsigned int *Init_Addr1 = ((unsigned int*)INIT_MEMORY_ADDR1);

#ifdef SYS14_WORKAROUND_REVE
#define INIT_MEMORY_ADDR2 0x0900
unsigned int *Init_Addr2 = ((unsigned int*)INIT_MEMORY_ADDR2);
#endif

int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer

// SYS14 Workaround
*Init_Addr1 = 0x7F00;
*(Init_Addr1+0x10) = 0x00E0;
*(Init_Addr1+0x20) = 0xC140;
*(Init_Addr1+0x30) = 0x07FF;

#ifdef SYS14_WORKAROUND_REVE
*Init_Addr2 = 0x9628;
*(Init_Addr2+4) = 0x0000;
*Init_Addr2 = 0x9600;
#endif

// Clock Configuration
UCSCTL4 = SELA_1; // ACLK = VLO

// Port Configuration
P1OUT = 0x00;P2OUT = 0x00;P3OUT = 0x00;P4OUT = 0x00;P5OUT = 0x00;P6OUT = 0x00;
PJOUT = 0x00;
P1DIR = 0xFF;P2DIR = 0xFF;P3DIR = 0xFF;P4DIR = 0xFF;P5DIR = 0xFF;P6DIR = 0xFF;
PJDIR = 0xFF;

__bis_SR_register(LPM3_bits); // Enter LPM3
__no_operation();
}

电路板只接JTAG，3.3v电源，断点在 __bis_SR_register(LPM3_bits); // Enter LPM3 功耗为 230ua正常，继续跑下去 还是230ua，拔掉JTAG功耗20ua不是手册上的2ua，是什么原因？？？？