LTC3852
9
3852f
TYPICAL PERFORMANCE CHARACTERISTICS
Charge Pump Output Ripple
Charge Pump Load Transient
Response
1µs/DIVV
IN1
= 3.3V
I
PUMP
= 25mA
C
VPUMP
= 4.7µF
V
PUMP
20mV/DIV
(AC-COUPLED)
3852 G38
10µs/DIVV
IN
= 3.3V
I
PUMP
= 25mA TO 50mA STEP
I
PUMP
50mA/DIV
V
PUMP
50mV/DIV
(AC-COUPLED)
3852 G39
3852 G40
V
IN1
(V)
1.8
V
PUMP
(V)
2.8 3.8 4.8
5.5
5
4.5
4
3.5
3
125°C
85°C
25°C
–45°C
Charge Pump Line Regulation
with 25mA Load
PIN FUNCTIONS
SENSE
–
(Pin 1): The (–) Input to the Current Sense
Comparators. Kelvin connect to V
OUT
at the current sense
resistor or, if DCR sensing is used, at the inductor.
SENSE
+
(Pin 2): Current Sense Comparator Noninverting
Input. The (+) input to the current comparator is normally
connected to the DCR sensing network or current sensing
resistor.
PGOOD (Pin 3): Power Good Indicator Output. Open drain
logic out that is pulled to ground when the output voltage
exceeds the ±10% regulation window, after the internal
17s power bad mask timer expires.
GND2 (Pin 4): Buck Controller Ground. All small-signal
components and compensation components should be
Kelvin connected to this ground. The (–) terminal of C
INTVCC
should be closely connected to this pin. The exposed pad
must be soldered to the PCB to provide electrical contact
for the IC and for optimum thermal performance.
BG (Pin 5): Bottom Gate Driver Output. This pin drives
the gate of the bottom N-channel MOSFET between GND
and INTV
CC
.
C
+
(Pin 7): Flying Capacitor Positive Terminal.
2.7 4.5
3.0
3.3
3.6 3.9 4.2
3852 G41
SUPPLY VOLTAGE (V
IN1
)
EFFICIENCY (%)
100
90
80
70
60
50
40
30
20
10
0
I
PUMP
= 1mA
THEORETICAL MAX
I
PUMP
= 10mA
I
PUMP
= 100mA
Effi ciency vs Supply Voltage
