zl2005 Intersil Corporation, zl2005 Datasheet - Page 24

• Manufacturer Part Number: zl2005
• Description: Digital-dc? Integrated Power Management And Conversion Ic
• Manufacturer: Intersil Corporation

The ZL2005 supports “lossless” current sensing, by
measuring the voltage across a resistive element that is
already present in the circuit. This eliminates addi-
tional efficiency losses incurred by devices that must
use an additional series resistance in the circuit.
To set the current limit threshold, the user must first
select a current sensing method. The ZL2005 incorpo-
rates two methods for current sensing, synchronous
MOSFET R
(DCR) sensing; Figure 14 shows a simplified sche-
matic for each method.
Table 17. Current Sensing Method Selection
NOTES:
1. 10 kΩ < R
2. The number of violations allowed prior to issuing a fault response.
ILIM0 Pin
R
R
R
ILIM0
ILIM0
ILIM0
Figure 14. Current Sensing Methods
1
ZL2005
ZL2005
ILIM0
DS(ON)
MOSFET R
Inductor DCR Sensing
< 100 kΩ
ILIM1 Pin
Resistor
OPEN
HIGH
LOW
ISENA
ISENB
ISENA
ISENB
sensing and inductor DC resistance
SW
SW
GH
GH
GL
GL
DS,ON
24
V
V
IN
IN
Sensing
Output-referenced, down-slope sensing
Ground-referenced (R
Output-referenced, up-slope sensing
Current Limiting Configuration
(Inductor DCR sensing)
(Inductor DCR sensing)
Blanking time: 672 ns
Blanking time: 352 ns
Blanking time: 352 ns
V
V
OUT
OUT
Depends on resistor value used; see Table 18
DS,ON
ZL2005
) sensing
The current sensing method can be selected using the
ILIM1 pin using Table 17. The ILIM0 pin must have a
finite resistor connected to ground in order for
Table 17 to be valid.
between ILIM0 and ground, the default method is
MOSFET R
method can be modified via the I
Please refer to Application Note AN13 for details
In addition to selecting the current sensing method, the
ZL2005 gives the power supply designer several
choices for the fault response during over or under
current condition. The user can select the number of
violations allowed before declaring fault, a blanking
time and the action taken when a fault is detected.
The blanking time represents the time when no current
measurement is taken. This is to avoid taking a reading
just after a current load step (Less accurate due to
potential ringing).It is a configurable parameter.
Table 17 includes default parameters for the number of
violations and the blanking time using pin-strap.
Number of
Violations
DS(ON)
Allowed
4
4
4
sensing. The current sensing
2
If no resistor is connected
Best for high duty cycle
Best for low duty cycle
Best for low duty cycle
2
and high f
and low f
C/SMBus interface.
Comments
February 18, 2009
SW
SW
FN6848.0
.