Kingbor Technology Co.,Ltd
TEL:(86)0755-26508846 FAX:(86)0755-26509052
KB3436
SHDN = Low: Shutdown, quiescent current < 1µA.
Output capacitor can be completely discharged through
the load or feedback resistors. A 150 resistor is
internally connected between SW and V
IN
.
V
OUT
(Pin 5):
Output Voltage Sense Input and Drain of the
Internal Synchronous Rectifier MOSFET. Bias is derived
from V
OUT
. PCB trace length from V
OUT
to the output filter
capacitor(s) should be as short and wide as possible. V
OUT
is completely disconnected from V
IN
when SHDN is low
due to the output disconnect feature.
V
IN
(Pin 6):
Battery Input Voltage. The device gets its
start-up bias from V
IN
. Once V
OUT
exceeds V
IN
, bias
comes from V
OUT
. Thus, once started, operation is com-
pletely independent from V
IN
. Operation is only limited by
the output power level and the battery’s internal series
resistance.
PIN FUNCTIONS
SW (Pin 1):
Switch Pin. Connect inductor between SW
and V
IN
. Keep these PCB trace lengths as short and wide
as possible to reduce EMI and voltage overshoot. If the
inductor current falls to zero, or SHDN is low, an internal
150 antiringing switch is connected from SW to V
IN
to
minimize EMI.
GND (Pin 2):
Signal and Power Ground. Provide a short
direct PCB path between GND and the (–) side of the output
capacitor(s).
FB (Pin 3):
Feedback Input to the
g
m
Error Amplifier.
Connect resistor divider tap to this pin. The output voltage
can be adjusted from 2.5V to 5V by:
V
OUT
= 1.00V • [1 + (R1/R2)]
SHDN (Pin 4):
Logic Controlled Shutdown Input.
SHDN = High: Normal free running operation, 650kHz
typical operating frequency.
SIMPLIFIED BLOC DIAGRAM
L1
+
1V TO 4.4V
6
V
IN
C
IN
V
OUT
GOOD
START-UP
OSC
A
B
A/B
MUX
1
SW
PWM
CONTROL
RAMP
GEN
650kHz
PWM
COMPARATOR
SYNC
DRIVE
CONTROL
SLOPE
COMP
SLEEP
Burst Mode
OPERATION
CONTROL
C
C
150pF
C
P2
2.5pF
SHDN
4
SHUTDOWN
CONTROL
SHUTDOWN
2
GND
+
R
C
80k
g
m
ERROR
AMP
–
–
+
V
IN
2.3V
0.45
WELL
SWITCH
V
OUT
5
2.5V TO 5V
0.35
C
PL
(OPTIONAL)
R1
CURRENT
SENSE
–
–
+
FB
3
1.00V
REF
R2
C
OUT
5
KINGBOR [ KINGBOR TECHNOLOGY CO ]
