请问AD7175-2单通道转换欠量程错误是什么原因？

目前一个项目采用了24bit的AD7175-2，在正常采样信号是会经常出现变成0值，状态寄存器的第六位置位，指示超量程或者欠量程错误，而且出现错误时除非把AD再次初始化否则不能正常采样。请教大家这个是什么原因？只用AD0通道采样，非差分。采样信号来自三节1.5V电池分压。
下面是AD7175的寄存器初始化配置：
  {0x00, 0x00,   1}, //Status_Register
   {0x01, 0x8000, 2}, //ADC_Mode_Register
  {0x02, 0x0100, 2}, //Interface_Mode_Register
   {0x04, 0x0000, 3}, //Data_Register
   {0x05, 0x0000, 2}, //IOCon_Register
   {0x07, 0x0000, 2}, //ID_st_reg
  {0x10, 0x8016, 2}, //CH_Map_1 REF- as AIN-
{0x11, 0x0000, 2}, //CH_Map_2
{0x12, 0x0000, 2}, //CH_Map_3
{0x13, 0x0000, 2}, //CH_Map_4
//{0x20, 0x1300, 2}, //Setup_Config_1
{0x20, 0x0300, 2}, //Setup_Config_1 BI_UNIPOLAR0
{0x21, 0x1300, 2}, //Setup_Config_2
{0x22, 0x1300, 2}, //Setup_Config_3
{0x23, 0x1300, 2}, //Setup_Config_4
{0x28, 0x020A, 2}, //Filter_Config_1
{0x29, 0x0200, 2}, //Filter_Config_2
{0x2a, 0x0200, 2}, //Filter_Config_3
{0x2b, 0x0200, 2}, //Filter_Config_4
{0x30, 0, 3}, //Offset_1
{0x31, 0, 3}, //Offset_2
{0x32, 0, 3}, //Offset_3
{0x33, 0, 3}, //Offset_4
{0x38, 0, 3}, //Gain_1
{0x39, 0, 3}, //Gain_2
{0x3a, 0, 3}, //Gain_3
{0x3b, 0, 3}, //Gain_4
{0xFF, 0, 1} //Communications_Register