LTC3809
3
3809fc
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 4.2V unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loops
Input DC Supply Current
Normal Operation
Sleep Mode
Shutdown
UVLO
(Note 4)
RUN = 0V
V
IN
= UVLO Threshold – 200mV
350
105
9
3
500
150
20
10
μA
μA
μA
μA
Undervoltage Lockout Threshold (UVLO) V
IN
Falling
V
IN
Rising
l
l
1.95
2.15
2.25
2.45
2.55
2.75
V
V
Shutdown Threshold of RUN Pin 0.8 1.1 1.4 V
Regulated Feedback Voltage (Note 5)
l
0.591 0.6 0.609 V
Output Voltage Line Regulation 2.75V < V
IN
< 9.8V (Note 5) 0.01 0.04 %/V
Output Voltage Load Regulation I
TH
= 0.9V (Note 5)
I
TH
= 1.7V
0.1
–0.1
0.5
–0.5
%
%
V
FB
Input Current (Note 5) 9 50 nA
Overvoltage Protect Threshold Measured at V
FB
0.66 0.68 0.7 V
Overvoltage Protect Hysteresis 20 mV
Auxiliary Feedback Threshold 0.325 0.4 0.475 V
Top Gate (TG) Drive Rise Time C
L
= 3000pF 40 ns
Top Gate (TG) Drive Fall Time C
L
= 3000pF 40 ns
Bottom Gate (BG) Drive Rise Time C
L
= 3000pF 50 ns
Bottom Gate (BG) Drive Fall Time C
L
= 3000pF 40 ns
Maximum Current Sense Voltage (ΔV
SENSE(MAX)
)
(V
IN
– SW)
IPRG = Floating (Note 6)
IPRG = 0V (Note 6)
IPRG = V
IN
(Note 6)
l
l
l
110
70
185
125
85
204
140
100
223
mV
mV
mV
Soft-Start Time (Internal) Time for V
FB
to Ramp from 0.05V to 0.55V 0.5 0.74 0.9 ms
Oscillator and Phase-Locked Loop
Oscillator Frequency Unsynchronized (SYNC/MODE Not Clocked)
PLLLPF = Floating
PLLLPF = 0V
PLLLPF = V
IN
480
260
650
550
300
750
600
340
825
kHz
kHz
kHz
Phase-Locked Loop Lock Range SYNC/MODE Clocked
Minimum Synchronizable Frequency
Maximum Synchronizible Frequency 750
200
1000
250 kHz
kHz
Phase Detector Output Current
Sinking
Sourcing
f
OSC
> f
SYNC/MODE
f
OSC
< f
SYNC/MODE
–3
3
μA
μA
Spread Spectrum Frequency Range Minimum Switching Frequency
Maximum Switching Frequency
460
635
kHz
kHz
SYNC/MODE Pull-Down Current SYNC/MODE = 2.2V 2.6 μA
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC3809E is guaranteed to meet specifi ed performance from
0°C to 85°C. Specifi cations over the –40°C to 85°C operating range are
assured by design characterization, and correlation with statistical process
controls.
Note 3: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
T
J
= T
A
+ (P
D
• θ
JA
°C/W)
Note 4: Dynamic supply current is higher due to gate charge being
delivered at the switching frequency.
Note 5: The LTC3809 is tested in a feedback loop that servos I
TH
to a
specifi ed voltage and measures the resultant V
FB
voltage.
Note 6: Peak current sense voltage is reduced dependent on duty cycle to
a percentage of value as shown in Figure 1.
