Bluetooth Low Energy detect disconnect

Question

This is my source code.

    private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() { 
     @Override 
     public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) { 
         if (newState == BluetoothProfile.STATE_CONNECTED) { 
                //source code

         } else if (newState == BluetoothProfile.STATE_DISCONNECTED) { 
               //source code

         } 
     } 

I have a question.

Actually, Bluetooth le disconnected already before 20 seconds. but This code is detecting disconnect after 20 seconds.

I want to know detecting disconnection immediately.

Give me solution. Plese . Thank you.