Datasheet

MAX8819A/MAX8819B/MAX8819C
PMIC with Integrated Chargers and Smart
Power Selector in a 4mm x 4mm TQFN
22 ______________________________________________________________________________________
The peak-to-peak inductor ripple current during PWM
operation is calculated as follows:
where f
S
is the 2MHz switching frequency.
The peak inductor current during PWM operation is cal-
culated as follows:
Step-Down Converter Maximum Output Current
The maximum regulated output current from a step-down
converter is ultimately determined by the p-channel peak
current limit (I
PK
). The calculation follows:
I
OUT_MAX
= I
PK
– (I
P-P
/2)
For example, if V
SYS
= 5.3V, V
OUT
= 3V, f
S
= 2MHz,
L = 4.7μH, and I
PK
= 0.6A:
I
P-P
= 3V x (5.3V - 3V)/(5.3V x 2MHz x 4.7μH) = 0.138A
then I
OUT_MAX
= 0.6A - (0.138A/2) = 0.531A.
II
I
L PEAK LOAD
PP
_
=+
−
2
I
VV V
VfL
PP
OUT SYS OUT
SYS S
−
=
−
××
()
+
-
+
-
+
-
+
-
6.0V RISING
400mV HYST.
4.0V RISING
500mV HYST.
SOFT-START
REG2
EN
OK
REG1OK
SOFT-START
REG1
EN
OK
REG2OK
SOFT-START
REG3
EN
OK
REG3OK
2.5V RISING
100mV HYST.
2MHz
OSC
BIAS
AND
REF
64 CYCLE
DELAY
(32µs)
+165°C
DIE TEMP
SYS
DC
EN4
DCPOK
READY
READY
REGON
DCOVLO
DCUVLO
SYSOK
DT165
SOFT-START
REG4
EN OK
REG4OK
EN123
REGON
MAX8819A
MAX8819B
Figure 5a. MAX8819A/MAX8819B Enable/Disable Logic