MAX1719EUT+T Maxim Integrated Products, MAX1719EUT+T Datasheet - Page 6

• Manufacturer Part Number: MAX1719EUT+T
• Description: IC VOLT INV SW CAP SOT23-6
• Manufacturer: Maxim Integrated Products
• Type: Switched Capacitor (Charge Pump), Invertingr

Specifications of MAX1719EUT+T

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: -1.5 ~ -5.5 V
• Current - Output: 25mA
• Frequency - Switching: 125kHz
• Voltage - Input: 1.5 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-6
• Power - Output: 696mW
• Function: Inverting
• Output Voltage: - 1.4 V to - 5.5 V
• Output Current: 25 mA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

SOT23, Switched-Capacitor
Voltage Inverters with Shutdown
Figure 2. Ideal Voltage Inverter
The MAX1719/MAX1720/MAX1721 are not voltage reg-
ulators: the charge pumps’ output resistance is
approximately 23Ω at room temperature (with V
+5V), and V
V
The droop of the negative supply (V
current draw from OUT (I
verter’s output resistance (R
The negative output voltage will be:
The efficiency of the MAX1719/MAX1720/MAX1721 is
dominated by its quiescent supply current (I
output current and by its output impedance (R
higher output current; it is given by:
6
Figure 1. Typical Application Circuit
1µF (10µF)
NOTE: ( ) CAPACITORS ARE FOR MAX1720.
*ON/OFF POLARITY OF SHDN IS REVERSED FOR MAX1719.
OUT
_______________________________________________________________________________________
1.5V to 5.5V
C3
INPUT
will droop toward GND as load current increases.
IN
OFF
ON
η ≅
OUT
V
S3
S1
V
OUT
I
DROOP-
OUT
2
5
I
approaches -5V when lightly loaded.
IN
SHDN
OUT
C1
= -(V
+
I
Efficiency Considerations
C1+
Q
6
MAX1719*
= I
1µF (10µF)
MAX1721
IN



1
OUT
GND
C1
OUT
S4
−
- V
S2
4
O
Charge-Pump Output
I
OUT
):
C1-
) times the negative con-
DROOP-
3
x R
OUT
O
V
×
IN
DROOP-
C2
1
R
)
OUT
R
L



) equals the
V
OUT
C2
1µF (10µF)
Q
) at low
NEGATIVE
OUTPUT
-1 · V
25mA
= -(V
OUT
IN
IN
IN
)
) at
=
where the output impedance is roughly approximated
by:
The first term is the effective resistance of an ideal
switched-capacitor circuit (Figures 3a and 3b), and
R
resistances (typically 8Ω to 9Ω at V
cal output impedance is more accurately determined
from the
The MAX1719/MAX1720/MAX1721 have a logic-con-
trolled shutdown input. Driving SHDN low places the
MAX1720/MAX1721 in a low-power shutdown mode.
The MAX1719’s shutdown input is inverted from that of
the MAX1720/MAX1721. Driving SHDN high places the
MAX1719 in a low-power shutdown mode. The charge-
pump switching halts, supply current is reduced to
1nA, and OUT is actively pulled to ground through a 4Ω
resistance.
To maintain the lowest output resistance, use capaci-
tors with low ESR (Table 1). The charge-pump output
resistance is a function of C1’s and C2’s ESR.
Therefore, minimizing the charge-pump capacitor’s
ESR minimizes the total output resistance. Table 2
gives suggested capacitor values for minimizing output
resistance or minimizing capacitor size.
Figure 3a. Switched-Capacitor Model
Figure 3b. Equivalent Circuit
SW
R
is the sum of the charge pump’s internal switch
OUT
V+
Typical Operating Characteristics.
V+
≅
R
(
C1
EQUIV
f
OSC
R
Applications Information
EQUIV
f
=
f
)
1
× C1
1
×
C1
+
C2
2R
C2
Capacitor Selection
Shutdown Mode
SW
+
4ESR
IN
R
L
= +5V). The typi-
V
R
OUT
L
V
C1
OUT
+
ESR
C2