2D Camera follow player up but not down

Hey everyone.

I'm using the code from the Unity 2D game example tutorial for my camera movement. Right now it follow the character in any direction.

What I want is that if my character moves up in the Y direction, the camera follows it, but if it moves down in the Y, the camera doesn't follow. Basically I want the bottom of the camera to be the kill trigger, so the player should never fall. I've tried several things to no success, any thoughts?

 using UnityEngine;
 using System.Collections;
 
 public class CameraFollow : MonoBehaviour {
 
     public float xMargin = 0f;
     public float yMargin = 0f;
     public float xSmooth = 0f;
     public float ySmooth = 0f;
     public Vector2 maxXAndY;
     public Vector2 minXAndY;
 
     private Transform player;
 
     void Awake ()
     {
         player = GameObject.FindGameObjectWithTag("Player").transform;
     }
 
     bool CheckXMargin() 
     {
         return Mathf.Abs (transform.position.x - player.position.x) > xMargin;
     }
 
     bool CheckYMargin() 
     {
         return Mathf.Abs (transform.position.y - player.position.y) > yMargin;
     }
 
     void FixedUpdate ()
     {
         TrackPlayer();
     }
 
     void TrackPlayer ()
     {
 
         float targetX = transform.position.x;
         float targetY = transform.position.y;
 
         if(CheckXMargin())
             targetX = Mathf.Lerp (transform.position.x, player.position.x, xSmooth * Time.deltaTime);
 
         if(CheckYMargin())
             targetY = Mathf.Lerp (transform.position.y, player.position.y, ySmooth * Time.deltaTime);
 
         targetX = Mathf.Clamp (targetX, minXAndY.x, maxXAndY.x);
         targetY = Mathf.Clamp (targetY, minXAndY.y, maxXAndY.y);
 
         transform.position = new Vector3(targetX, targetY, transform.position.z);
 
     }
 
 }