3
LTC3736
3736fa
ELECTRICAL CHARACTERISTICS
The ● denotes specifications that apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
= 4.2V unless otherwise specified.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC3736E is guaranteed to meet specified performance from
0°C to 70°C. Specifications 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 LTC3736 is tested in a feedback loop that servos I
TH
to a
specified 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.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage Load Regulation I
TH
= 0.9V (Note 5) 0.12 0.5 %
I
TH
= 1.7V –0.12 –0.5 %
V
FB1,2
Input Current (Note 5) 10 50 nA
TRACK Input Current TRACK = 0.6V 10 50 nA
Overvoltage Protect Threshold Measured at V
FB
0.66 0.68 0.7 V
Overvoltage Protect Hysteresis 20 mV
Auxiliary Feedback Threshold SYNC/FCB Ramping Positive 0.525 0.6 0.675 V
Top Gate (TG) Drive 1, 2 Rise Time C
L
= 3000pF 40 ns
Top Gate (TG) Drive 1, 2 Fall Time C
L
= 3000pF 40 ns
Bottom Gate (BG) Drive 1, 2 Rise Time C
L
= 3000pF 50 ns
Bottom Gate (BG) Drive 1, 2 Fall Time C
L
= 3000pF 40 ns
Maximum Current Sense Voltage (∆V
SENSE(MAX)
) IPRG = Floating ● 110 125 140 mV
(SENSE
+
– SW) IPRG = 0V ● 70 85 100 mV
IPRG = V
IN
● 185 204 223 mV
Soft-Start Time Time for V
FB1
to Ramp from 0.05V to 0.55V 0.667 0.833 1 ms
Oscillator and Phase-Locked Loop
Oscillator Frequency Unsynchronized (SYNC/FCB Not Clocked)
PLLLPF = Floating ● 480 550 600 kHz
PLLLPF = 0V
● 260 300 340 kHz
PLLLPF = V
IN
● 650 750 825 kHz
Phase-Locked Loop Lock Range SYNC/FCB Clocked
Minimum Synchronizable Frequency ● 200 250 kHz
Maximum Synchronizable Frequency
● 850 1150 kHz
Phase Detector Output Current
Sinking f
OSC
> f
SYNC/FCB
–4 µA
Sourcing f
OSC
< f
SYNC/FCB
4 µA
PGOOD Output
PGOOD Voltage Low I
PGOOD
Sinking 1mA 125 mV
PGOOD Trip Level V
FB
with Respect to Set Output Voltage
V
FB
< 0.6V, Ramping Positive –13 –10.0 –7 %
V
FB
< 0.6V, Ramping Negative –16 –13.3 –10 %
V
FB
> 0.6V, Ramping Negative 7 10.0 13 %
V
FB
> 0.6V, Ramping Positive 10 13.3 16 %
