MAX8614B Maxim Integrated Products, MAX8614B Datasheet - Page 9

• Manufacturer Part Number: MAX8614B
• Description: (MAX8614A / MAX8614B) Dual-Output (+ and -) DC-DC
• Manufacturer: Maxim Integrated Products

The MAX8614A/MAX8614B generate both a positive and
negative output voltage by combining a step-up and an
inverting DC-DC converter on one IC. Both the step-up
converter and the inverter share a common clock. Each
output is independently regulated.
Each output is separately controlled by a pulse-width-
modulated (PWM) current-mode regulator. This allows
the converters to operate at a fixed frequency (1MHz)
for use in noise-sensitive applications. The 1MHz
switching rate allows for small external components.
Both converters are internally compensated and are
optimized for fast transient response (see the Load-
Transient Response/Voltage Positioning section).
_______________________________________________________________________________________
Detailed Description
ONBST
ONINV
AV
FLT
SEQ
CC
GND
CONTROL
BLOCK
BIAS
AND
Dual-Output (+ and -) DC-DC
1.01V
OSCILLATOR
SOFT-START
1MHz
AMPLIFIER
AMPLIFIER
REFERENCE
ERROR
ERROR
CURRENT SENSE
CURRENT SENSE
1.25V
INVERTER
STEP-UP
The step-up converter generates a positive output volt-
age up to 24V. An internal power switch, internal True-
Shutdown load switch (PVP), and external catch diode
allow conversion efficiencies as high as 90%. The inter-
nal load switch disconnects the battery from the load
by opening the battery connection to the inductor, pro-
viding True Shutdown. The internal load switch stays on
at all times during normal operation. The load switch is
used in the control scheme for the converter and can-
not be bypassed.
COMPARATOR
COMPARATOR
PWM
PWM
Converters for CCD
INVERTER
CONTROL
CONTROL
STEP-UP
LOGIC
LOGIC
MAX8614A
MAX8614B
Functional Diagram
Step-Up Converter
V
LXN
FBN
REF
PVP
LXP
PGND
FBP
CC
9