MSP-EXP430FR5969: LPM4功耗实际测试与手册描述不符

我使用MSP430FR5969评估板的J9测试电流，进入LPM4时测得的电流为20μA左右，与手册中描述的0.4μA差别过大，代码如下。

问一下评估板是否可以达到0.4μA的功耗

int main(void)
{
volatile int i = 0;
volatile int j = 0;
WDTCTL = WDTPW | WDTHOLD; // stop watchdog timer

// P1DIR |= BIT0;
// P1OUT |= BIT0;
P4DIR |= BIT6;
P4OUT &= ~BIT6;
P4DIR &= ~BIT5;
P4REN |= BIT5;
P4OUT |= BIT5;
PM5CTL0 &= ~LOCKLPM5;
while(1)
{
// __bis_SR_register(LPM4);
if((P4IN&BIT5) == 0)
{
P1DIR = 0xFF; P1OUT = 0x00;
P2DIR = 0xFF; P2OUT = 0x00;
P3DIR = 0xFF; P3OUT = 0x00;
P4DIR = 0xFF; P4OUT = 0x00;

ADC12CTL0 = 0; // 关闭 ADC
TA0CTL = 0; // 关闭 Timer_A
UCA0CTLW0 |= UCSWRST; // 关闭 UART
PMMCTL0_H = PMMPW_H; // 解锁 PMM
PMMCTL0_L |= PMMREGOFF; // 关闭稳压器
LPM4; // 进入LPM4
}
P4OUT ^= BIT6;
for(i = 0; i < 125; i++)
{
for(j = 0; j <100; j++);
}
}
}