AAT1187A Advanced Analog Technology, Inc., AAT1187A Datasheet - Page 24

• Manufacturer Part Number: AAT1187A
• Description: Boost Converter For Wled Driver
• Manufacturer: Advanced Analog Technology, Inc.

Setting the V
Choose a Zener diode to be in parallel connection with
the V
Zener to have a break down current around 1mA, the
charge pump circuit requires resistor, R
connection.
V
V
Setting the LDO Voltage
The LDO can supply up to 600mA current and it is
suitable to supply voltage for T
LDO voltage is set by the resistor divider from the V
to GND with a center tap connected to the ADJ.
V
(Figure 10) has a value between 5.1k
calculate R
R
GL
Z
LDO
13
= Zener diode voltage
= –V
Figure 9. The Negative Charge Pump Circuit
feedback voltage is typically 1.24V. Assume R
GL
R
14
Z
output node. Because it’s essential for the



13
V
V
to satisfy the following equation.
LDO
ADJ
Figure 10. LDO Circuit
GL
1
Output Voltage



Advanced Analog Technology, Inc.
CON.
and 51k
–
15
, in series
–
Advanced Analog Technology, Inc . –
台 灣 類 比 科 技 股 份 有 限 公 司
and
Page 24 of 28
LDO
Version 1.00
14
Setting the Reset Voltage
The AAT1187A series has an integrated reset voltage
detector with an open drain output. (Figure 11)
Once V
RESET pin would be pulled low by internal NMOS. V
can be calculated as below
Recommended R
R
V
DETECT
13



VDIV
V
DETECT
–
1.1V
Figure 11. Reset Function Block
1.1V
is under VDIV threshold voltage, 1.1V, the
14 value



1
1



R
R
R
is between 5.1k and 30k .
13
14
14
：



AAT1187A
September 2009
IN