X3100-01 Datasheet, PDF (21/41 Pages) Intersil Corporation – Cell Balancing Control

X3100, X3101
Table 24. Over-Current Protection Mode—Event Diagram Description (Continued)
Event
[3]
(3,4)
[4]
Event Description
— The device detects the load resistance has risen above R_OCR.
— Voltages P+ and VCS₂₁ return to their normal levels.
— The test current from pin OVP/LMON is stopped (I_LMON = 0µA)
— The device has now returned from the load monitor state
— The internal over-current release time timer begins counting down.
— Device is still in over-current protection mode.
The internal over-current release timer continues counting for T_OCR seconds.
— The internal over-current release timer times out, and VCS₂₁ is still below V_OC.
— The device returns from over-current protection mode, and is now in normal operation mode.
— The discharge FET is automatically switched ON (UVP/OCP = Vss)—unless the status of UVPC has been
changed in the control register during the over-current protection mode.
— The status of the charge FET remains unaffected.
— Discharge of the battery cells is once again possible.
MONITOR MODE
Analog Multiplexer Selection
The X3100 and X3101 can be used to externally monitor
individual battery cell voltages, and battery current. Each
quantity can be monitored at the analog output pin (AO),
and is selected using the analog select (AS0 - AS2) pins
(Table 25). Also, see Figure 7.
Table 25. AO Selection Map
AS2 AS1 AS0
AO output
L
L
L V_SS(1)
L
L H VCELL₁ - VCELL₂ (VCELL₁₂)
L
H
L VCELL₂ - VCELL₃ (VCELL₂₃)
L
H H VCELL₃ - VCELL₄ (VCELL₃₄)
H L L VCELL₄ - Vss (VCELL₄)
H
L
H VCS₁ - VCS₂ (VCS₁₂)⁽²⁾
H
H
L VCS2 - VCS₁ (VCS₂₁)⁽²⁾
H
H
H V_SS
Notes: (1) This is the normal state of the X3100 or X3101. While
in this state Over-charge and Over-discharge Protec-
tion conditions are periodically monitored (See “Peri-
odic Protection Monitoring” on page 13.)
(2) VCS₁, VCS₂ are read at AO with respect to a DC bias
voltage of 2.5V (See section “Current Monitor Func-
tion” on page 21).
Current Monitor Function
The voltages monitored at pins VCS₁ and VCS₂ can be
used to calculate current flowing through the battery
terminals, using an off-board microcontroller with an A/D.
Since the value of the sense resistor (R_SENSE) is small
(typically in the order of tens of mΩ), and since the
resolution of various A/D converters may vary, the
voltage across R_SENSE (VCS₁ and VCS₂) is amplified
internally with a gain of between 10 and 160, and out-
put to pin AO (Figure 7).
Figure 7. X3100/X3101 Monitor Circuit
Cell 1 Voltage
Voltage
Level
Shifters
Cell 2 Voltage
Cell 3 Voltage
Cell 4 Voltage
AS0
AS1
AS2
2.5V
AO
R2
OP1
+
-
R1
R2
R1
S0
Config _Gain
SPI
SCL
Register Setting
CSG1 CSG0
I/F
CS
SI
Cross-Bar
Switch
Over-Current
Protection
VCS₁
VCS₂
R_SENSE
X3100/X3101
P-
21
FN8110.1
January 3, 2008