Datasheet

ADP1614 Data Sheet
Rev. A | Page 12 of 20
THEORY OF OPERATION
The ADP1614 current-mode, step-up switching converter
boosts a 2.5 V to 5.5 V input voltage to an output voltage as
high as 20 V. The internal switch allows a high output current,
and the 650 kHz/1.3 MHz switching frequency allows the use of
tiny external components. The switch current is monitored on a
pulse-by-pulse basis to limit the current to the value set by the
R
CL
resistor on the CLRES pin on the adjustable current-limit
version or to 3 A typical on the fixed current-limit version.
SW
PWM
COMPARATOR
UVLO
COMPARATOR
TSD
COMPARATOR
OSCILLATOR
S
R
Q
D
COMPARATOR
D
R
E
F
+
+
VIN
VIN
CURRENT
SENSING
FREQ
DRIVER
BAND GAP
N1
BG
RESET
NOTES
1. THE PORTIONS IN THE DASHED BOXES DISPLAY THE TWO POSSIBLE FUNCTIONALITIES OF PIN 9 ON THE ADP1614.
1.1MΩ
AGND
V
IN
UVLO
REF
T
SENSE
T
REF
ERROR
AMPLIFIER
V
BG
2
1
5.5µA
V
SS
R
COMP
C
COMP
COMP
SS
FB
C
SS
R1
R2
R
CL
C
IN
V
OUT
8
L1
D1
A
V
OUT
C
OUT
6
SW
7
39 5
GND
4
GND
11
EP
AGND
ENCLRES
ADP1614
ADP1614ACPZ-R7
5.5µA
9
10
V
IN
ON
OFF
1.3MHz
650kHz
SOFT
START
10293-024
ADP1614ACPZ-650-R7
AND
ADP1614ACPZ-1.3-R7
Figure 32. Block Diagram with Step-Up Regulator Application Circuit