CM4072 Datasheet, PDF (1/11 Pages) California Micro Devices Corp – Low Noise Charge Pump/Linear Regulator LED Driver

PRELIMINARY
CM4072
Low Noise Charge Pump/Linear Regulator LED Driver
Features
• Low noise regulator with integrated charge pump
voltage-booster
• 5V output with input voltage as low as 2.8V
• Charge pump can also power an external LDO
• Low noise in 20Hz to 20kHz audio band
• Up to 200mA continuous output current
• Low operating and shutdown currents
• Stable with low-ESR ceramic or tantalum capaci-
tors
• Over-current and over-temperature protection
• 10-lead TDFN package, 3mm x 3mm
• Lead-free versions available
Applications
• White backlight LEDs for main display in wireless
handsets and LCD modules
• Power flash LEDs for camera phones
• 3.3V to 5V conversion in PCMCIA cards, PCI
Express Cards, other applications needing 5V
• 5V analog supply for audio codec in notebook
computers, PDAs, MP3 players, etc
Product Description
The CM4072 Low-noise Charge Pump / LDO Regulator is
designed to power white backlight LEDs used in main dis-
plays or camera flash LEDs in wireless handsets. The 5V
output provides up to 100mA continuous current for input
voltages from 3.0V to 5.5V, and up to 200mA for a nar-
rower range. This is accomplished with an integrated
charge pump that boosts the input voltage before feeding
it to an internal LDO linear regulator. The CM4072 oper-
ates with excellent power supply ripple rejection while
maintaining good power efficiency. The device utilizes two
external capacitors and operates at 250kHz. Separate
analog and digital ground pins are provided for the charge
pump and the rest of the circuitry to eliminate ground
noise feed-through from the charge pump to the regulated
output.
The CM4072 provides both overcurrent and thermal over-
load protection. Two enable inputs provide flexibility in
powering down the device. To maximize power saving in
shutdown mode, both enable inputs should be at a logic
low level. For applications that require the 5V output to be
re-established with minimum delay after shutdown, the
charge pump can be left enabled while the regulator is
disabled. The CMOS LDO regulator features low quies-
cent current even at full load, making it very suitable for
power sensitive applications.
A bypass pin is provided to further minimize noise by con-
necting an external capacitor between this pin and
ground.
The CM4072 is available in a 10-lead TDFN package,
with optional lead-free finishing, and is ideal for space crit-
ical applications.
Typical Application
Simplified Block Diagram
1
V_IN
2
3
2.2Cμ^SF ⁺
4
C_BYP ⁺
5
0.1μF*
*Optional
PWM
0-200kHz
10
9
CM4072
TDFN-10
8
7
6
+ 1Cμ^PF
DGND ¹
V_IN ²
V_CP
3
C_S
EN_CP ⁷
EN_LDO ⁶
CHARGE PUMP
10 ^CP-
C_P
9
CP+
ENABLE CHARGE
PUMP
CONTROL
CIRCUIT
ENABLE LDO
V_REF
CS
LDO
8 _VOUT
5
BYP
4
GND
© 2005 California Micro Devices Corp. All rights reserved.
11/08/05
490 N. McCarthy Blvd., Milpitas, CA 95035-5112 ● Tel: [phone] ● Fax: [phone] ● www.cmd.com
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