CS5159GD16 View Datasheet(PDF) - ON Semiconductor
Part Name
Description
MFG CO.
'CS5159GD16' PDF : 16 Pages View PDF
CS5159
5.0 V
R1
10 k
VOUT
CS5159
R3
10 k
PN3904
R2
6.2 k
Power Good
PN3904
Figure 17. Implementing Power Good with the CS5159
M 5.00 ms
Trace 4− 5.0 V from PC Power Supply (2.0 V/div.)
Trace 1− Regulator Output Voltage (1.0 V/div.)
Figure 15. OVP Response to an Input−to−Output Short
Circuit by Pulling the Input Voltage to Ground
External Output Enable Circuit
On/off control of the regulator can be implemented
through the addition of two additional discrete components
(see Figure 16). This circuit operates by pulling the Soft
Start pin high, and the VFFB pin low, emulating a short
circuit condition.
5.0 V
Shutdown
Input
MMUN2111T1 (SOT−23)
IN4148
5 SS
CS5159
8 VFFB
Figure 16. Implementing Shutdown with the CS5159
External Power Good Circuit
An optional Power Good signal can be generated through
the use of four additional external components (see Figure
17). The threshold voltage of the Power Good signal can be
adjusted per the following equation:
VPower
Good
+
(R1
)
R2)
R2
0.65 V
This circuit provides an open collector output that drives
the Power Good output to ground for regulator voltages less
than VPower Good.
M 2.50 ms
Trace 3 − 12 V Input (VCC1) and (VCC2) (10 V/div.)
Trace 4− 5.0 V Input (2.0 V/div.)
Trace 1− Regulator Output Voltage (1.0 V/div.)
Trace 2− Power Good Signal (2.0 V/div.)
Figure 18. CS5159 Demonstration Board During Power
Up. Power Good Signal is Activated when Output
Voltage Reaches 1.70 V.
Selecting External Components
The CS5159 can be used with a wide range of external
power components to optimize the cost and performance of
a particular design. The following information can be used
as general guidelines to assist in their selection.
NFET Power Transistors
Both logic level and standard MOSFETs can be used. The
reference designs derive gate drive from the 12 V supply
which is generally available in most computer systems and
utilize logic level MOSFETs. Multiple MOSFETs may be
paralleled to reduce losses and improve efficiency and
thermal management.
Voltage applied to the MOSFET gates depends on the
application circuit used. Both upper and lower gate driver
outputs are specified to drive to within 1.5 V of ground when
in the low state and to within 2.0 V of their respective bias
supplies when in the high state. In practice, the MOSFET
gates will be driven rail to rail due to overshoot caused by the
capacitive load they present to the controller IC. For the
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