8.3.9 Bias Supply Regulator (VCC, VLDOIN)

VCC is the output of the internal LDO subregulator used to supply the control circuits of the TLVM13610. The

nominal VCC voltage is 3.3 V. The VLDOIN pin is the input to the internal LDO. Connect this input to VOUT to

provide the lowest possible input supply current. If the VLDOIN voltage is less than 3.1 V, VIN1 and VIN2 directly

power the internal LDO.

To prevent unsafe operation, VCC has UVLO protection that prevents switching if the internal voltage is too low.

See VCC_UVLO and VCC_UVLO_HYS in the Section 7.5.

VCC must not be used to power external circuitry. Do not load VCC or short it to ground. VLDOIN is an optional

input to the internal LDO. Connect an optional high quality 0.1-µF to 1-µF capacitor from VLDOIN to AGND for

improved noise immunity.

The LDO provides the VCC voltage from one of two inputs: VIN or VLDOIN. When VLDOIN is tied to ground

or below 3.1 V, the LDO derives power from VIN. The LDO input becomes VLDOIN when VLDOIN is tied to a

voltage above 3.1 V. The VLDOIN voltage must not exceed both VIN and 12 V.

Equation 7 specifies the LDO power loss reduction as:

PLDO-LOSS = ILDO × (VIN-LDO – VVCC)

(7)

The VLDOIN input provides an option to supply the LDO with a lower voltage than VIN, thus minimizing the LDO

input voltage relative to VCC and reducing power loss. For example, if the LDO current is 10 mA at 1 MHz with

VIN = 24 V and VOUT = 5 V, the LDO power loss with VLDOIN tied to ground is 10 mA × (24 V – 3.3 V) = 207

mW, while the loss with VLDOIN tied to VOUT is equal to 10 mA × (5 V – 3.3 V) = 17 mW – a reduction of 190

mW.

Figure 8-3 and Figure 8-4 show typical efficiency plots with and without VLDOIN connected to VOUT.

Output Current (A)

0

1

2

3

4

5

6

7

8

70

75

80

85

90

95

100

VVLDOIN = VOUT

VVLDOIN = GND

VIN = 24 V

VOUT = 5 V

FSW = 1 MHz

Figure 8-3. Efficiency Increase With External Bias

Output Current (A)

0

1

2

3

4

5

6

7

8

70

75

80

85

90

95

100

VVLDOIN = VOUT

VVLDOIN = GND

VIN = 36 V

VOUT = 5 V

FSW = 1 MHz

Figure 8-4. Efficiency Increase With External Bias

8.3.10 Overcurrent Protection (OCP)

The TLVM13610 is protected from overcurrent conditions using cycle-by-cycle current limiting of the peak

inductor current. The current is compared every switching cycle to the current limit threshold. During an

overcurrent condition, the output voltage decreases.

The TLVM13610 employs hiccup overcurrent protection if there is an extreme overload. In hiccup mode, the

TLVM13610 module is shut down and kept off for 40 ms (typical) before a restart is attempted. If an overcurrent

or short-circuit fault condition still exists, hiccup repeats until the fault condition is removed. Hiccup mode

reduces power dissipation under severe overcurrent conditions, thus preventing overheating and potential

damage to the device. After the fault is removed, the module automatically recovers and returns to normal

operation.

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TLVM13610

SLVSH63 – FEBRUARY 2023

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