YB1901
2.0A High-Side Power Switch with Flag
Function Block
VIN
UVLO
Charge
pump
OSC
BIAS
EN
Current
Limit
VOUT
Delay
Thermal
Protection
OCB
GND
Figure 3: Function Block
Functional Description
The YB1901 is an N-channel high-side
power switch with an internal charge-pump
circuitry to drive the switch. The enable
signal is either active high. It is ideal for
battery-powered applications and adaptor
card operation with less than 2.0A
requirement.
NMOS Switch
The drain of the NMOS is connected to V
IN
and the source to V
OUT
. The bulk contact is
grounded, instead of the source terminal,
so there is no parasitic diode between the
two terminals. It prevents reverse current
flow from V
OUT
to V
IN
if V
OUT
being forced to
higher voltage than V
IN
when the enable is
inactive. This feature makes the main
difference between YB1901 and a
traditional external MOSFET.
Chip Enable
The enable signal is available with either or
active low of customer’s request. When the
enable is inactive, the switch is turned off,
the internal oscillation stopped, the charge
pump discharged, and the whole chip
current consumption is kept at lower than
0.1μA typically. When the enable is set
active, the oscillation starts, the charge
pump works. But it takes time building up
the control voltage necessary to drive the
MOSFET switch. The turn-on delay time is
around 0.42ms typically.
Floating the enable pin may cause
unpredictable operation. It should be
avoided.
Under-Voltage Lock-Out (UVLO)
UVLO prevents the chip from turning on
until a safe input voltage is reached. For
YB1901 UVLO is set to around 2.4V, and
there is a hysteresis voltage of 0.2V
7
YB1901 Rev.1.2
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YOBON [ YOBON TECHNOLOGIES,INC. ]
